Speedy feet athletics club systems analysis Assignment

Speedy feet athletics club systems analysis - Assignment Example He will then come up with the calendar of the competitions that will be done in a given season. iii. Hannah (Venues Advisor) is the person responsible with managing venues and the facilities that are available in each of the venues. Hannah is responsible with ensuring that the venues are in good condition for the competitions that are coming. iv. Timekeeper is the person who is responsible with ensuring that time is followed and all activities are done according to the stipulated time. v. Athlete is key person taking place in in the competition. User specifications From the use case diagram, the use case that I will give specifications is that of Ethan, the club competition advisor. He manages most of the processes that happen within the club. He ensures that the athletes get the calendar and make sure that the venues are in order. He compiles the calendar basing on the facilities that are available in each of the venue. Some of the user specifications for the competitions advisor ar e stated below: i. The system should be able to give the available venues that competition can take place ii. The system should give the athletes that have been accepted to take part in the competition in a given season iii. It should give the facilities that are available in a given venue so that the competition can be scheduled basing on this information iv. The it should give the days that competitions can take place v. It should list the people who can supervise the various competitions vi. It should give the list of the athletes that have been rejected so that letters can be sent to them vii. It should be able to send letters to rejected athletes viii. It should have the time keepers who will manage the time of the competitions. Usability goals Basing on the competitions advisor, the usability goals that are required include: i. Effectiveness. Will the system do what is designed to do? The system should do what has been designed to do. The effort to come up with a list of compe titions and athletes for a given season. ii. Utility. Does the system, provide enough utility to carry out tasks that are done by a competitions advisor as natural as possible? The usability of the system should be able to accommodate a range of tasks that are normally done by competitions advisor. iii. Efficiency. This usability goal tries to answer the question of time. How long will the competitions advisor take to handle issues that are at hand? The new system should be efficient so that it takes less time to perform the tasks designed to perform. It should take less time to perform tasks that have been designed to be done. It should be faster while scheduling and compiling the calendar (Dennis, Wixom & Roth 2008). User experience goals The system should be able to enhance the experience of the user when using the system. In our case example, the following are the user experience that is required for the competitions advisor: i. Should be satisfying. The system should satisfy th e needs of the competitions advisor so that he is able to be productive in what he does. It should be productive and meet the needs of a competitions advisor. ii. The system should also be rewarding. The competitions advisor should be able to feel that he has been productive in undertaking the tasks that have been assigned to him. The competitions advisor should be in a position to undertake the tasks that have been assigned and be able to undertake what has he has been doing in the manual process and

Personal Interview of a Friend Essay -- Interviews essays research pap

I interview my friend, Tim F. Mr. F was born on January 08, 1976 Cleveland, Ohio to M. J. and J. F. Mr. F. prefers to be addressed as Tim. He is mixed, Tim’s mother is mixed with black and white and his father is black. His dad left them when he was twelve years old but still came around every now and again. She remarried when he was eighteen. He is an African American male at the age of twenty-eight. He came from a middle class family, but his had more money than she leaded him believe. He was an only child but he had plenty aunt and uncles to go around. His mother came from a big family. She had three older brothers, two younger sisters and a younger brother. She was the middle child. Having three older brothers they always were harder on her she said, because she was the oldest of the younger girls. That’s why he felt that his mother was so hard on him. Mr. F is a kind-hearted person. I thought I knew Mr. F very well until I did this interview. He showed a side that I never knew he had. Mr. F attends New Harvest Church. Mr. F currently stays here in Montgomery, Alabama with his daughter Nicole. Instead of going to college Mr. F joined the Marines at the age of twenty-three. He wanted to make a better life for his self because he said that he was going to end up dead or in jail and that is two places that he did not want to be. Mr. F felt like the Marines would be the best route to not only developing him into manhood but also providing him with the best thing to do. â€Å"I wanted to be a better person and open up doors of opportunity for myself. I wanted to provide for my family, buy a house and be able to live comfortably. During the four years he was in the Marines, Mr. F traveled thought the United States and around the world to Japan, Australia, Korea, Panama and the Philippines while traveling he was available to get numerous certification in computer programming.   Ã‚  Ã‚  Ã‚  Ã‚  Mr. F lives in Town Lakes in Montgomery, Alabama upper class area. He is one of a few black neighbors in the whole neighborhood. Sometimes he feels that he should have not moved out there, because he wants his daughter to feel what it is like to not be handed everything in life. Mr. F loves his daughter to no end, but Nicole’s mother on the other hand, he say he could just live without. Mr. F weakness is he gives into his daughter too easily. As a child Mr. F he often found himsel... ...the question. That is one thing that I feel that I did not do enough of, is to keep on and stay on track of the answering of certain questions. He had seemed to be in a fun mood the day we did the interview. Earlier that week he and his mother got into a disagreement about something. He did not say what it was at the time but now I know it was because Mrs. J-F was upset because she has not seen her grand-daughter in almost a year. I was pleased to that he agreed to do the interview, after having a bad week earlier. When I told him that I would be video taping him he was ecstatic. He was in a playful mood. I listened to everything my client had to say and wanted to say. I also took notes on some things that we should have talked about in our next meeting. I showed good body language to my client. He knew I was paying attention to him because I was nodding my head and restating some of his comments to him answer. Some of the things I need to work on would be is to just let him continue talking and not cut him off so much. I feel that because Mr. F and I are very good fri ends and that is why I feel that cut him off so much, but I think I can and will do much better next time.

In the play “Twelfth Night” Shakespeare bases the plot around a variety of different themes

In the play ‘Twelfth Night', Shakespeare bases the plot around a variety of different themes. The themes of disguise, music, loss and death are subtly introduced, however, the main theme of love is dramatically introduced by Orsino's first line; ‘If music be the food of love play on'. As well as using a variety of themes, ‘Twelfth Night' incorporates the different kinds of love that can have an effect on people. These types of love range from brotherly love to instantaneous love and from unrequited love to impossible love. The use of the theme of love enables almost everybody to relate to events in the play. Love evokes a number of emotions and is a main ingredient, which brings comedy into the play. In Act 1:1 we see Olivia's reaction to the death of her brother. Olivia takes grieving very seriously; ‘†¦she hath abjured herself from the sight and company of men', and takes a vow of chastity. She plans to mourn her brother for seven years and she hides herself from the world; ‘But like a cloisters she will veilà ¯Ã‚ ¿Ã‚ ½d walk'. Olivia chooses to dwell on her loss and her strict mourning period could be seen as selfish as life must go on. However, Olivia uses her brother's death to shut herself away from life. In Act 1:5 Feste tries to prove Olivia a fool for taking her mourning period to such an extent. Feste cleverly tells Olivia that her brother's soul is in hell. She protests and insists that his soul is in heaven; Feste then uses his quick-witted nature and says; ‘The more fool madonna, to mourn for your brother's soul being in heaven†¦' Another example of brotherly love is shown when we meet Viola after the shipwreck in Act 1:2. She too ‘suffers the loss' of a beloved brother but unlike Olivia, Viola takes decisive action following his apparent death. She reacts sensibly and practically to a traumatic situation. She desperately wants her brother to be alive; ‘O my poor brother! And so perchance may he be!'. However she realises that she must react calmly and productively to get by in life; ‘I'll serve this Duke†¦.'. Viola's love for Sebastian makes her determined and persistent to carry on. In Act 2:1 we see Sebastian's caring nature and his mourning for his sister; ‘She is drownà ¯Ã‚ ¿Ã‚ ½d already, sir, with salt water though I seem to drown her remembrance again with more'. Sebastian shows intense feelings of love and the desire to be reunited with his sister. When he sees Viola dressed as Cesario, he says if she were a woman; ‘I should let tears fall upon your cheek, And say, ‘Thrice welcome, drownà ¯Ã‚ ¿Ã‚ ½d Viola'. Viola's determination and Sebastian's deeply affectionate feelings towards his sister depict the closeness between he siblings. Instantaneous love is the most frequent type of love experienced by the characters throughout the play. In Act 1:1 we learn how Orsino fell in love with Olivia from a distance; ‘When mine eyes did first see Olivia first, me thought she purged the air of pestilence'. This sighting of Olivia puts Orsino in a melodramatic, melancholy, lovesick mood. These feelings, however, start to eat away at him. Here he uses food imagery, ‘If music be the food of love play on' and also shows his changeable fickle character when he says, ‘Enough; no more. ‘Tis not so sweet now as it was before.' This could also mean that if he has too much of a good thing, i.e. love, he will become sick of it and stop loving Olivia. Orsino can't express his feelings for Olivia and it is not long before we find that Olivia is actually in love with Viola/Cesario. We know that this is instantaneous love because Viola is dressed as a man, and she has fallen for his appearance. It is evident that Olivia likes Viola/Cesario because she takes off her veil, ‘†¦in the sight and company' of a ‘man', when he/she comes to woo her for Orsino. She tells Viola/Cesario that she cannot love Orsino and says, ‘Let him no more-unless you come to me again.' Here she tells Orsino to stop wooing her, unless he is to send Viola/Cesario to do so. Olivia does not comprehend how it is possible to fall in love so quickly; ‘Even so quickly may one catch the plague?'. ‘To creep in at mine eyes' could also indicate love at first sight. Desperate to see Viola/Cesario again, Olivia sends Malvolio after the youth, telling him; ‘He left this ring behind him'. It is in Act 2:2when Malvolio confronts Viola with the ring, Viola realises that Olivia loves her; ‘She loves me sure; the cunning of her passion, Invites me in this churlish messenger.' Instantaneous love is also introduced when Olivia and Sebastian meet, when she tries to prevent Sir Toby from drawing sword on whom she believes to be Cesario. Sebastian immediately falls in love with Olivia; ‘If it be thus a dream, still let me sleep!' and despite her calling him Cesario, agrees to marry her. Although Orsino loves Olivia for her outward appearance he also falls for Cesario's inner character. He appreciates Viola/Cersario's trustworthy character and after only a short period of time a strong bond ahs between the two; ‘I have unclasped to thee my secret soul'. In Act 1:5 Orsino comments on Viola's womanly attributes and nature; ‘Diana's lip is not more smooth and rubious; thy small pipe is as the maiden's organ shrill and sound'. This is a good example of irony as Orsino is not yet aware that Viola/Cesario is actually a woman. After spending much time alone with Orsino, Viola falls in love. Her feelings start to fester, as she can't express her love due to her disguise; ‘But let concealment like a worm i'th' bud Feed on her damask cheek'. Viola is very subtle about her feelings towards Orsino yet she cleverly and indirectly tells him that she loves him; ‘As it may be perhaps, were I a woman, I should your lordship.' It is in Act 5:1 that Viola openly declares her love for Orsino. Orsino angrily leaves and Viola follows telling Olivia that she is going; ‘After him I love, more than I love these eyes, more than my life. ‘ This explicit declaration of love comes despite Viola being disguised as a man. She also declares her love implicitly in the ‘willow cabin' speech in Act 1:5 during, which she expresses the passion and rawness in the love that she has for Orsino. Impossible/forbidden love is also featured in the play. In Act 1:3 Sir Andrew tells of how he plans to woo Olivia but worries; ‘Your niece will not be seen, or if she be, it's four to one, she'll none of me'. Sir Toby, then, misleadingly says to Sir Andrew; ‘Tut there's life in't man.' Here Sit Toby is telling Sir Andrew where there is life there is hope. Sir Andrew does not realise when people are taking advantage of his gullibility to make him the butt of their jokes. In Act 3:2 Sir Toby persuades Sir Andrew to challenge Viols/Cesario to a duel in order to impress Olivia; ‘there is no love-broker in the world can more prevail in mans commendation with woman that report valour.' In a final attempt to woo Olivia Sir Andrew agrees to the duel with Cesario. This is an example of irony, as we know his attempts will not be triumphant as Olivia is in love with Cesario. Malvolio also has feelings for Olivia but his feelings are for selfish motives; ‘To be count Malvolio!' Here Malvolio dreams of marrying Olivia even though he is merely a steward. He then says ;'There is example for it: the Lady of the Strachy married the yeoman of the wardrobe.' He says this to justify his dreams and to make himself believe that he will have a chance of ‘love' with Olivia. He is gulled into feeling that he in fact does have a chance with Olivia when Maria leaves a fraudulent letter ‘from Olivia'. Malvolio's self-love allows him to assure himself that Olivia did in fact write the letter and that she does love him. Malvolio doesn't need much persuading and he immediately sets about following the letters instructions; ‘He's in yellow stockings' which are ‘most villainously cross gartered.' It seems that Malvolio ‘does obey every point of the letter', showing his foolish, self-absorbed nature. We, again, know that Malvolio doesn't have a chance of happiness with Olivia, not only because she is in love with Cesario but also because he is ‘merely a steward'. One of the more successful relationships that develops from friendship to love is that between Sir Toby and Maria. In the earlier scenes of the play we see the flourishing relationship between the two. They subtly show their feelings to one another throughout the play. This is evident whilst they indulge in verbal banter. Maria makes their early friendship obvious when she tells how she worries about Toby's luxurious lifestyle; ‘That drinking and quaffing will undo you'. Toby, however, expresses his feelings in a more crude way; ‘board her, woe her, assail her'. The formulating plan to ‘gull' Malvolio strengthens Maria and Toby's relationship; ‘I could marry that wench for this device'. Toby refers to Maria using comic comparisons, ‘she is a beagle true bred' and ‘good night Penthesila', commenting on her diminutive size. In Act 2:5 Toby greet Maria with; ‘How now, my metal of India?' proving that he thinks highly of her, comparing her to pure gold. We see how far their relationship has progressed when in Act 5:1 Fabian informs the characters; ‘Maria writ the letter, at Sir Toby's great importance, In recompense whereof he hath married her'. The most memorable example of love in the play is that of Orsino's for Viola. Not only does the idea of a man falling for ‘another man' add comedy value to the play, it also provides some touching heart rendering scenes. Many of these scenes evoke sympathy towards Viola as she can't express her returned feeling for Orsino due to her disguise; ‘my father had a daughter loved a man as it might be perhaps, where I a woman I should your lordship'. In Twelfth Night the theme of love brings comedy to the play and evokes a number of feelings such a sympathy, wonder, confusion and of course laughter. It also confronts issues, which many people can relate to, making Twelfth Night a fun and memorable play.

The Unbounded Reach of Rhetoric Essay - 840 Words

The Unbounded Reach of Rhetoric In the year of 1938, during the Nuremburg Conference, a man stands up to deliver the closing speech. This speech is not particularly as well known or as significant as many of his other speeches, but the words of this thin and paunchy man are strong and resolute. He states, â€Å"When the question is still put to us why National Socialism fights with such fanaticism against the Jewish element in Germany, why it pressed and still presses for its removal then the answer can only be: Because National Socialism desires to establish a true community of the people†¦. Because we are National Socialists, we can never suffer an alien race which has nothing to do with us to claim the leadership of our working people†¦show more content†¦In Book One of the Persian Expedition, Clearchus, a general of Cyrus, handles a potential mutiny from the Greek mercenary soldiers when they become suspicious of Cyrus’s motives. â€Å"At first Clearchus tried to force his own soldiers t o go forward, but they threw stones at him and at his baggage animals as soon as they attempted to make a start. Clearchus was very nearly stoned to death on this occasion (Warner 65).† Realizing that force was not going to work, he appeals to the method of rhetoric by making a speech and having two of his men deliver a pre-constructed speech. He coyly feigns loyalty to the soldiers while he simultaneously makes it seem that going against Cyrus would be impossible. Although still suspicious, the soldiers reluctantly decide to go with and fight for Cyrus. This scene depicts rhetoric overcoming brute force in the promotion of violence. Rhetoric is a form of action and without it many of the events in the novel would have either never occurred or gone quite differently. In the PanHellenic dialogues by Xenophon, the army is not only motivated to continue on in their endeavors but he also clears their conscious about committing barbaric acts. This can been seen when he addresses t he army and says, â€Å"But when we come to a place where we are given no opportunities to buy food, then, whether it is native country or Greek country, we take our own supplies and do this not out of wanton aggression, but from necessity (Warner 240).† In OnShow MoreRelated The Doctrine of President Bush Essay2238 Words   |  9 Pagesa military buildup in hopes of surpassing, or equaling, the power of the United States. Balance, indeed. The doctrine goes beyond the preemption theme sounded by President Bush in a West Point speech last June. Read beneath its kitchen-sink rhetoric and you see, in black and white, Bush codifying the unilateral treaty-busting moves of his first months in office -- his rejection of the Kyoto climate-change protocol, his cancellation of the ABM accord, his obstruction of the bioweapons treatyRead More Simulation Proliferation and the City Essay3639 Words   |  15 Pagesof the requirement and definition of freedom as forever only fantasy and thus a pursuant total cession of reality to control and power. Freedom is unreal. A bit ironic for any politics resembling Martin Luther King’s famous integrationist dream rhetoric. While it seems an escape that the land of fantasy has no boundaries, this does not mean that it can intrude on the real world, but that the real world is always tangible in its fantasy double. Like objects picked up by angels in Wings of DesireRead MoreCan You Say What Your Strategy Is5768 Words   |  24 Pagesscope, and advantage—and rightly believed that executives should be forced to be crystal clear about them. These elements are a simple yet sufï ¬ cient list for any strategy (whether business or military) that addresses competitive interaction over unbounded terrain. Any strategy statement must begin with a deï ¬ nition of the ends that the strategy is designed to achieve. â€Å"If you don’t know where you are going, any road will get you there† is the appropriate maxim here. If a nation has an unclear senseRead MoreRastafarian79520 Words   |  319 Pagesliberation and a future Ethiopian empire.20 In this respect, Psalm 68:31, â€Å"Princes shall come out of Egypt; Ethiopia shall soon stretch out her hands unto God,† was interpreted as a prophecy of African redemption. Casely Hayford, author of Ethiopia Unbounded, held out hope of an â€Å"African racial redemption.† Furthermore, Hayford referred to Edward Wilmot Blyden, who repatriated to Liberia and became a distinguished professor and statesman, as â€Å"God descended upon the earth to teach the Ethiopians anew

History Is Brimming With Great Accomplishments And Great...

History is brimming with great accomplishments and great mistakes. Thomas Edison once replied when asked why he continued working after so many failures, â€Å"I didn t fail, I found 10,000 ways that didn t work.† This is a contrary view to the ignorant being condemned to repeating the past. People who are familiar with the past simply do not make the same mistakes. Of course they wouldn t because they know how NOT to accomplish their goals. Another way of looking at the past is tan alternate phrase, â€Å"Hindsight is 20/20.† It captures the idea that past mistakes were made and remains ambiguous whether those mistakes will or will not be made during similar future events. The Closing of the Thompson Street Pool doesn t exactly fall under the category of something that those who are ignorant of the past being doomed to repeat unless you consider the outcome and what was done to reach it. The only people who could learn anything from it are the government officia ls in charge of the budget, but let s face it, the government never learns from it s mistakes. If that were the case, our government would work on fixing our own financial problems before sending billions of dollars overseas to rebuild countries that we were at war with after EVERY war. Shouldn t the people who pay the taxes have some say in where that money goes? If I have to work to pay the government, I would like to know why my money is going to Iraq to force them to establish a government in America sShow MoreRelatedI Hear America Singing By Walt Whitman2049 Words   |  9 Pages In Walt Whitman’s poem â€Å"I Hear America Singing†, one is exposed to an America seen by the eyes of a poet, essayist and journalist during the years of one of the most important times in American history, the Civil War. From 1819 to 1892, Whitman lived through many experiences, including the atrocities and successions of the Civil War, which not only lead to the establishment of hi s multiple accredited works, but also, the creation of the prideful, positive, jubilant image of America and its citizensRead MoreLet Every Nation Know - Worksheet Answers1841 Words   |  8 Pagesstand and fight, not be an innocent bystander in the legislative process (from speech and pg. 22). He also called the current President tired and perplexed; out of touch with WWII vets. â€Å"He [Eisenhower] was detached at a time when the country was brimming with vigor†¦ When times demanded focus, he was aimless† (speech). In defense to the attacks of his Catholic faith, JFK asked this rhetorical question; â€Å"I’m able to serve in congress, and my brother was able to give his life, but we can’t be presidentRead MoreSAT Top 30 Essay Evidence18536 Words   |  75 Pages................................................. 31 Lord of the Flies, by William Golding (Murderous schoolboys stranded on an island!) ......................... 33 The Great Gatsby, by F. Scott Fitzgerald (The famous American novel) ................................................ 35 Historical Events: The American Great Depression (1929-1930s) ........................................................................................ 37 World War I (1914-1918) ..............................Read MoreFundamentals of Hrm263904 Words   |  1056 PagesStress Interview 163 The Behavioral Interview 164 Realistic Job Previews 164 Conditional Job Offers 165 Background Investigation 165 Medical/Physical Examination 167 Job Offers 168 The Comprehensive Approach 168 WORKPLACE ISSUES: Avoiding Hiring Mistakes 169 Now It’s Up to the Candidate 169 Selection for Self-Managed Teams Reliability 171 Validity 171 Content Validity 171 Construct Validity 172 Criterion-Related Validity 172 Recruiting: A Global Perspective 146 DID YOU KNOW?: Posting Online Rà ©sumà ©s

The Integrity of Humanity Explored in The Tragedy of King...

In our world, there are people like the woman who yells at her children and disciplines them with physical punishment, but also the boy who talks to the student that always sits alone at the lunch table and is socially different than others. Some people may lead a life based upon universally established morals, while others tend to let out a side of their being that is more beastly than human. Humans have the ability to make choices based on reason, while the animals of the earth have only the capacity to choose the best option for their own survival. Human reasoning, both gracious and grave is witnessed in the words of William Shakespeare’s play, The Tragedy of King Lear. Through both provocative and seemingly angelic characters,†¦show more content†¦Belief in the expression of love through action and not flattery or wealth identifies Cordelia as greater than the acquisitive and inconsiderate Lear who proves his deficiency of a moral conscience and that he has room t o deepen his understanding of human worth. A more literal form of nakedness is taken on by Edgar as he lives the seemingly degrading life of a beggar. At his worst, he declares, â€Å"Thou unsubstantial air that I embrace!/ The wretch that thou hast blown unto the worst/ Owes nothing to thy blasts.† (Shakespeare IV. I. 7-9), and realizes that for hope of a more righteous future, sometimes people must be stripped down to the core and be at their worst in order to eliminate deep-rooted habits. This interpretation of Shakespeare’s references to â€Å"nothing† suggests the importance of removing the essentially meaningless aspects of life that hold back the integral traits of humanity, and reveal the treacherous corruption that all humans are capable of. Likewise, the labels of foolishness and wisdom that are placed on characters are a false recognition of identity because of the misconception of what it means to be wise and noble or to be a foolish knave at the bas e of society. King Lear thinks of himself as wise at first, but ironically his fool proves to be wisest and claims that Lear’s actions regarding his daughters have only confirmed his folly. This makes Lear a clear example of what it means to be ignorant to the human ideaShow MoreRelatedKing Lear1057 Words   |  5 PagesShakespeare’s King Lear is a timeless play whose textual integrity lends itself to a variety of interpretations and in exploring the human condition the text remains relevant across a wide range of contexts. It is possible to present the text as exploring and affirming the human condition, where humanity is defined as the ability to love and empathise. However, in the same instance, a nihilist perspective, such as Peter Brooke’s 1971 production of King Lear, challenges this by outlining that humanity as anRead MoreWilliam Shakespeare s Much Ado About Nothing And King Lear3685 Words   |  15 PagesName: Instructors’ Name: Course: Date: Analysis of Shakespeare’s powerful female characters in the play â€Å"Much Ado about Nothing† and â€Å"King Lear Introduction Shakespeare is seen to value the role of women as his plays often portray women as heroines. These women have strong characters that endear them to readers. Readers in our current world, and especially women, are encouraged to be self-assertive in demand for equal treatment in our society. This has been the tradition for women in the Western

Grignard Reagent Free Essays

1598 Organometallics 2009, 28, 1598–1605 CoVer Essay The Grignard Reagents Dietmar Seyferth Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 ReceiVed February 4, 2009 During the past 100 years the Grignard reagents probably have been the most widely used organometallic reagents. Most of them are easily prepared in ethereal solution (usually diethyl ether or, since the early 1950s, THF) by the reaction of an organic halide with metallic magnesium (eq 1). Table 1. We will write a custom essay sample on Grignard Reagent or any similar topic only for you Order Now Composition of Diethyl Ether Solutions of Various Grignard Reagents at Equilibrium (in mol %), 2RMgX h R2Mg + MgX2a RX in RX + Mg reacn CH3I C2H5I C2H5Br C2H5Cl n-C3H7I n-C3H7Br n-C3H7Cl C6H5I C6H5Br a RMgX 87. 0 43. 0 41. 0 15. 0 24. 0 24. 0 17. 0 38. 0 30. 0 R2Mg ) MgX2 6. 5 28. 5 29. 5 42. 5 38. 0 38. 0 41. 5 31. 0 35. 0 RX + Mg f RMgX (X ) Cl, Br, I) (1) Most of them are stable in ethereal solution (although atmospheric moisture and oxygen should be excluded) and in general are quite reactive. Discovered by Victor Grignard at the University of Lyon in France in 1900,1 their ease of preparation and their broad applications in organic and organometallic synthesis made these new organomagnesium reagents an instant success. The importance of this contribution to synthetic chemistry was recognized very early, and for his discovery Grignard was awarded a Nobel Prize in Chemistry in 1912. Our cover molecule is the monomeric ethylmagnesium bromide bis(diethyl etherate) (1), whose solid-state molecular structure was determined by an X-ray diffraction study by Lloyd Guggenberger and Robert Rundle in 1964 using crystals isolated from a diethyl ether solution of a C2H5Br/Mg reaction mixture by slow cooling with a stream of cold gaseous nitrogen. 2-4 Adapted from: Schlenk, W. , Jr. Ber. Dtsch. Chem. Ges. 1931, 64, 734. Wilhelm Schlenk and his son discovered 80 years ago, more than one magnesium-containing species exists in the diethyl ether solution of a Grignard reagent. 5 A redistribution of the substituents on magnesium takes place, and the RMgX species ends up in equilibrium with the two symmetrical species, the diorganomagnesium and the magnesium dihalide: the â€Å"Schlenk Equilibrium† (eq 2). 2RMgX h R2Mg + MgX2 (2) Generally written as â€Å"RMgX† in textbooks, monographs and research papers, the Grignard reagents in ethereal solution are more complicated than this simple formula indicates. As (1) (a) Grignard, V. Compt. rend. Hebd. Seances Acad. Sci. 1900, 130, ? 1322. (b) Grignard, V. Dissertation â€Å"Theses sur les combinaisons organo` magnesie nes mixtes et leur application a des syntheses†, University of Lyon, ` ` Lyon, France, 1901. (2) (a) Guggenberger, L. J. ; Rundle, R. E. J. Am. Chem. Soc. 1964, 86, 5344. (b) Guggenberger, L. J. ; Rundle, R. E. J. Am. Chem. Soc. 1968, 90, 5375. 3) A crystalline solid, CH3MgI  · (n-C5H11)2O, was isolated and identi? ed as such by elemental analysis (Mg and I) in 1908: Zerewitinoff, Th. Ber. Dtsch. Chem. Ges. 1908, 41, 2244. The oxonium structure The species that contain Mg-halogen bonds can be precipitated from Grignard reagent solutions in diethyl ether by the addition of 1,4-dioxane. An insoluble, polymeric 1,4-dioxane adduct is formed, leaving behind a solution of R2Mg5sa useful preparation of dialkyl- and diarylmagnesium reagents. 6 Wilhelm Schlenk, Jr. analyzed the 1,4-dioxane precipitations from a number of Grignard reagent solutions. Assuming that the precipitation is essentially instantaneous, i. e. , that the calculated R2Mg, MgX2, and RMgX percentages re? ect the ac tual composition of the Grignard reagent solution at equilibrium, Schlenk reported the compositions collected in Table 1. Direct evidence (5) Schlenk, W. ; Schlenk, W. , Jr. Ber. Dtsch. Chem. Ges. 1929, 62, 920. (6) (a) Cope, A. C. J. Am. Chem. Soc. 1935, 57, 2238. (b) As Erwin Weiss found, evaporation of diethyl ether solutions of methyl- and ethylmagnesium bromide and chloride at reduced pressure followed by heating of the colorless solid residues at ca. 00  °C and 0. 001 mmHg for several hours gave a mixture of the respective pure, solvent-free, polymeric R2Mg compounds and magnesium halides. The solid MgCl2 thus obtained differed from a sample obtained from a MgCl2 melt in that its lattice showed a strong stacking disorder. This form of MgCl2 had an extremely high surface area: Weiss, E. Chem. Ber. 1965, 98, 2805. (7) Schlenk, W. , Jr. Ber. Dtsch. Chem. Ges. 1931, 64, 734 Further additions to the examples in Table 1 were soon thereafter reported by other workers: (a) Noller, C . R. ; Hilmer, F. B. J. Am. Chem. Soc. 1932, 54, 2503. (b) Johnson, G. O. Adkins, H. J. Am. Chem. Soc. 1932, 54, 1943. (c) Cope, A. C. J. Am. Chem. Soc. 1934, 56, 1578. was written for this compound. Earlier workers had isolated noncrystalline solid samples of etherates, e. g. , C2H5MgI  · (C2H5)2O and RMgI  · 2(C2H5)2O. (4) Other early Grignard reagent crystal structures: (a) Stucky, G. D. ; Rundle, R. E. J. Am. Chem. Soc. 1964, 86, 4825 (C6H5MgBr  · 2Et2O). (b) Vallino, M. J. Organomet. Chem. 1969, 20, 1 (CH3MgBr  · 3THF). . 10. 1021/om900088z CCC: $40. 75 ? 2009 American Chemical Society Publication on Web 03/16/2009 Organometallics, Vol. 28, No. 6, 2009 1599 Figure 1. Association of several Grignard compounds in tetrahydrofuran (J. Am. Chem. Soc. 1969, 91, 3847. ). that solutions of â€Å"CH3MgBr† in diethyl ether contain CH3MgBr and (CH3)2Mg was obtained by Ashby and co-workers by means of 1H NMR spectroscopic measurements at -105  °C. Solutions of â€Å"t-butylmagnesium chloride† in diethyl ether also were studied. 8 The tendency of the halide substituents in the RMgX and MgX2 species present in ethereal solution at equilibrium to form bridges between magnesium atoms, Mg-X-Mg, in a Lewis base/Lewis acid type interaction further complicates the nature of the Grignard reagent in ethereal solvents. In a very thorough study of the association factors of various Grignard reagents in diethyl ether and THF by careful ebullioscopic molecular weight measurements, Eugene Ashby and Frank Walker at the Georgia Institute of Technology found that monomeric, dimeric, and higher oligomeric species were present, depending on the solvent and the halogen and the organic substituents on the magnesium atom. 9 Included in this study along with data for the â€Å"RMgX† solutions were data for a few R2Mg compounds and for the magnesium dihalides. As Figure 1 shows, the observed association factor (the i value is the apparent molecular weight divided by the formula weight of the monoetherate) shows that the Grignard reagents and (C6H5)2Mg are close to monomeric in the relatively strong Lewis basic THF. The picture is quite different in diethyl ether solution (Figures 2 and 3), with association factors of 1 to nearly 4 for solute concentrations up to ca. 3 molal. It is not clear what these i values mean in terms of the actual species present in these solutions. On the assumption that the Schlenk equilibrium is operative in all cases, in view of the presence of a signi? cant concentration of MgX2, one cannot expect only simple solvated species of type i(R)Mg-X] n [ i (average n ) i). Toney and Stucky isolated crystals of a dimeric species, 2, from a solution of â€Å"C2H5MgBr† in di-n-butyl ether by addition of this solution to triethylamine. 10 The molecular Figure 2. Association of alkylmagnesium chlorides in diethyl ether. Demonstration of importance of halogen vs R group in determining the form of association in diethyl ether (J. Am. Chem. Soc. 1969, 91, 3848. ). Figure 3. Association of several alkyl- and arylmagnesium bromides and iodides and related magnesium compounds in diethyl ether (J. Am. Chem. Soc. 1969, 91, 3848. ). structure, as determined by X-ray analysis, contained a double Br bridge with the ethyl groups in a trans arrangement. That (8) In â€Å"CH3MgBr† solutions in diethyl ether: (a) Ashby, E. C. ; Parrish, G. ; Walker, F. Chem. Commun. 1969, 1464. (b) â€Å"(CH3)3CMgCl† solutions in diethyl ether at-26  °C: Parris, G. ; Ashby, E. C. J. Am. Chem. Soc. 1971, 93, 1206. (9) (a) Walker, F. W. ; Ashby, E. C. J. Am. Chem. Soc. 1969, 91, 3845. (b) Ashby, E. C. Bull. Soc. Chim. Fr. 1972, 2133 (review, in English). (c) Meisenheimer, J. ; Schlichenmaier. Ber. Dtsch. Chem. Ges. 1928, 61 (an earlier, similar, but more limited study in diethyl ether). more complicated structures can be present in an â€Å"RMgX† solution in diethyl ether was demonstrated by the determination of the X-ray crystal structure of a crystalline compound obtained from a THF solution of â€Å"C2H5MgCl† of composition C2H5Mg2Cl3. This compound was not a simple Cl-bridged dimer, as the empirical formula might suggest. Actually, it was a tetramer (Figure 4) in which the Mg atoms have a coordination number greater than 4. 1 There is a caveat, however: the species that crystallizes from a Grignard reagent solution does not necessarily directly re? ect what species are swimming around in the solution. The crystalline solid shown in Figure 4 could well have self-assembled during the crystallization process by combination of two molecules of the C2H5Mg2Cl3 dimer and not been present in solution at all. Even in the case of monomeric â€Å"RMgX† in THF solution, the Schlenk equilibrium will be operative and the strongly Lewis basic THF apparently prevents halide bridging between Mg atoms. Consequently, the (10) Toney, J. ; Stucky, G. D. Chem. Commun. 1967, 1168. (11) Toney, J. ; Stucky, G. D. J. Organomet. Chem. 1971, 28, 5. 1600 Organometallics, Vol. 28, No. 6, 2009 Scheme 1 Figure 4. Molecular structure of [C2H5Mg2Cl3(C4H8O)3]2, a tetrameric Grignard reagent. Modi? ed from Toney and Stucky (J. Organomet. Chem. 1971, 28, 15. (copyright 1971, with permission from Elsevier)). presence of monomeric RMgX, R2Mg, and MgX2, all solvated, would result in the measurement of an association factor of 1, as Walker and Ashby observed. There are so many factors that bear on the question of the constitution of a given Grignard reagent in ethereal solutionsthe Lewis basicity and steric properties of the ether solvent, the electronegativity and size of the halogen atom in RMgX, the nature and steric properties of the organic substituent on the magnesium atom. These will affect the magnitude of the equilibrium constant of the Schlenk equilibrium and the extent of Mg-X-Mg bridging. For most applications in synthetic chemistry it will suf? ce to take the easy way outsto regard and to write the Grignard reagent as RMgX. There is another interesting and useful property of ethereal Grignard reagent solutions. The magnesium species are weak electrolytes in such solvents of low dielectric constant, and â€Å"RMgX† solutions conduct an electric current. 12 The electrolysis of solutions of organomagnesium halides was studied in some detail by Kondyrew at the State Research Institute in Leningrad13 and by Ward Evans and his students at Northwestern University. 14 During the electrolysis, magnesium species migrate both to the cathode and to the anode. Scheme 1 shows the simplest picture based on RMgX. Metallic magnesium is formed at the cathode. 12) The earliest report appears to be a 1912 French paper: Jolibois, P. Compt. rend. Hebd. Seances Acad. Sci. 1912, 155, 213. See also: Nelson, ? J. M. ; Evans, W. V. J. Am. Chem. Soc. 1917, 39, 82. (13) (a) Kondyrew, N. W. Ber. Dtsch. Chem. Ges. 1925, 58, 459. (b) Kondyrew, N. W. ; Manojew, D. P. Ber. Dtsch. Chem. Ges. 1925, 58, 464. (c) Kondyrew, N. W. Ber. Dtsch. Chem. Ges. 1928, 61, 208. (d) Kondyrew, N. W. ; Ssusi, A. K. Ber. Dtsch. Chem. Ges. 1929, 62, 1856. (14) The Evans group published many papers in J. Am. Chem. Soc. during the 1933-1942 period. See, for example: (a) Evans, W. V. ; Lee, F. H. J. Am. Chem. Soc. 1934, 56, 654. (b) Evans, W. V. ; Field, E. J. Am. Chem. Soc. 1936, 58, 720. (c) Evans, W. V. ; Braithwaite, D. J. Am. Chem. Soc. 1939, 61, 898. (d) Evans, W. V. ; Braithwaite, D. ; Field, E. J. Am. Chem. Soc. 1940, 62, 534. (e) Evans, W. V. ; Pearson, R. J. Am. Chem. Soc. 1942, 64, 2865. The alkyl radicals formed at the anode can undergo the usual alkyl radical processes of coupling (to R-R), disproportionation (to RH + R(-H)), or, if the anode is composed of a reactive metal such as zinc, aluminum, cadmium, or lead, they can attack the anode to form an organometallic compound. A graduate student of Evans, David G. Braithwaite, joined the Nalco Chemical Co. after he graduated and developed an electrolytic process for the commercialscale syntheses of tetramethyl- and tetraethyllead antiknock agents in which the respective alkyl Grignard reagents were electrolyzed in a mixed THF/diethylene glycol dimethyl ether solvent system using a lead anode and a steel cathode. 15 The reactions of the Grignard reagents with organic, organometallic, and inorganic substrates and their applications are too numerous and varied to be covered here. Not only do they ? nd extensive use on a small to moderate scale in research laboratories but they also have been prepared and utilized on a large scale in diverse industrial processes. For the most part they react as nucleophilic reagents, as would be expected, on the basis of the polarity of the carbon-magnesium bond, C? –Mg? +. However, they also can undergo electron transfer reactions with appropriate electron-acceptor substrates. They are weak bases capable of deprotonating the stronger weak organic acids such as terminal acetylenes and cyclopentadiene. Their basicity can be enhanced (as can be the basicity of organolithium reagents) by the addition to RMgX solutions in ethers of additives such as hexamethylphosphoric triamide (HMPA) and N-methyl-2-pyrrolidinone (NMP) or alkali-metal alkoxides. All such information can be found in books devoted solely or in part to Grignard reagents. 16 Two special topics are of current interest and merit special mention. (1) The preparation of highly functionalized organomagnesium reagents by Paul Knochel and his co-workers at the University of Munich17 by means of halogen-magnesium exchange (e. . , eq 3). The availability of reagents such as 3-8 (which must be utilized at low temperature) has added a new and spectacular dimension to Grignard reagent chemistry. (2) The synthesis of ole? ns, styrenes, 1,3-dienes and biaryl derivatives by the crosscoupling of Grignard reagents with organic halides. The crosscoupling of Grignard reagents with vinylic halides was discovered by Morris Kharasch and Charl es Fuchs at the University of Chicago Organometallics, Vol. 28, No. 6, 2009 1601 Table 2. Transition Metal Halide Catalyzed Homocoupling of Phenylmagnesium Iodidea metal halide FeCl2 CoBr2 NiBr2 RuCl3 RhCl3 PdCl2 OsCl3 IrCl3 a amt, mol 0. 01 0. 01 0. 03 0. 0036 0. 0036 0. 00566 0. 00275 0. 003 amt of C6H5MgI, mol 0. 03 0. 03 0. 095 0. 0108 0. 013 0. 0163 0. 007 0. 01 yield of biphenyl, % 98 98 100 99 97. 5 98 53 28 Taken from: J. Am. Chem. Soc. 1939, 61, 957. in 1943 during the classic studies of Kharasch on the chemistry of Grignard reagents in the presence of transition-metal halides. 6b Kharasch and Fuchs found that arylmagnesium bromides in diethyl ether reacted readily with vinylic halides of type RCHdCHX and R2CdCHX (but not CH2dC(R)X) to give styrenes in 50-75% yield when the reactions were carried out in the presence of 5 mol % of CoCl2 (eq 4). 18It was reported that other metal halides (of iron, nickel, and chromium) also were effective catalysts of this cross-coupling reaction. Benzylmagnesium chloride also reacted in this manner with vinyl bromide to give PhCH2 CHdCH2 in 75% yield. Alkylmagnesium halides such as cyclohexyl- and n-butylmagnesium bromide, on the other hand, gave only â€Å"small to negligible† yields of the expected coupling product. The ArMgBrderived biaryl usually was obtained as a byproduct in these reactions. Such homocoupling of arylmagnesium halides in the presence of a transition metal halide as well as copper and silver halides was a known reaction. It had been investigated in 1939 by Gilman and Lichtenwalter, who found that aryl Grignard reagents undergo homocoupling in the presence of ca. 0 mol % of various transition-metal halides in diethyl ether solution to give the respective biaryl in high yield in most cases (eq 5, Table 2). 19 The metal halide, in addition to being the needed catalyst precursor, also served as an oxidizing agent and, in some cases (CoBr2, NiCl2, RhCl3), formation of a black solid indicated complete reduction to the metal. not occur in the absence of the organic halide but in its presence was vigorously exo thermic. The added organic halide was only partially consumed and did not show up in the biaryl product. When p-bromotoluene was added to a phenylmagnesium bromide/CoCl2 catalyst reaction mixture, only biphenyl was formed. A remarkable reaction! smost likely a free radical process, as Kharasch suggested. The organic halide was believed to function as an oxidizing agent. This interesting, simple, and potentially useful cross-coupling reaction, as exempli? ed in eq 4, was not adopted by the synthetic organic community right away. After a long dormancy it was rediscovered some 30 years later by a number of groups in the USA, Japan, and France, all of whom apparently were not aware of the 1943 Kharasch/Fuchs JACS paper. 1 Transition-metal catalysts other than CoCl2 were used, but the concept and the basic reaction were the same. In 1971 Tamura and Kochi reported a thorough study of the cross-coupling of Grignard reagents with vinylic halides catalyzed by soluble iron species in concentrations of ca. 10-4 M in THF at 0-25  °C. 26,27 Various Fe(III) compounds could be used as Fe catalyst pr ecursors; the best were Fe(III) -diketonates such as Fe(RC(O)CHC(O)R)3 (R ) Ph, CH3, t-Bu). These exothermic reactions were not free radical processes. The reactions of cis- and trans-propenyl bromide proceeded with retention of geometric con? uration (eqs 6 and 7) and were not adversely affected by the presence of 0. 4 M styrene. A ArMgBr + RCHdCHX 9 ArCHdCHR + MgBrX 8 (X ) Cl, Br) CoCl2 5 mol % (4) 2ArMgX + MXn f Ar-Ar + MgX2 + MXn-2 (5) A novel catalytic process for such ArMgX to Ar-Ar coupling was discovered by Kharasch and Fields when ethereal solutions of an aryl Grignard reagent that contained a catalytic amount (3 mol %) of CoCl2 were heated at re? ux for 1 h and then treated with an equivalent amount of an organic halide (C6H5Br, C2H5Br, i-C3H7Cl). 20 The coupling reaction to give Ar-Ar did (15) (a) Bott, L. L. Hydrocarbon Process. Petrol. Re? ner 1965, 44, 115. (b) Guccione, E. Chem. Eng. 1965, (June 21), 102. See also Part 2 of the tetraethyllead essay: (c) Seyferth, D. Organometallics 2003, 22, 5154 (pages 5172-5174). (16) (a) Krause, E. ; von Grosse, A. Die Chemie der metall-organischen Verbindungen; Gebruder Borntrager: Berlin, 1937; pp 14-61, 110-114. ? ? (b) Kharasch, M. S. ; Reinmuth, O. Grignard Reactions of Nonmetallic Substances; Prentice Hall: New York, 1954. (c) Handbook of Grignard Reagents; Silverman, G. S. , Rakita, P. E. , Eds. ; Dekker: New York, 1996. d) Grignard Reagents-New DeVelopments; Richey, H. G. , Ed. ; Wiley: Chichester, New York, 2000. (e) The Chemistry of Organomagnesium Compounds; Rappaport, Z. , Marek, L. , Eds. ; Wiley-VCH: Weinheim, Germany, 2008. (17) Knochel, P. ; Dohle, W. ; Gommermann, N. ; Kneisel, F. F. ; Kopp, F. ; Korn, T. ; Sapountzis, J. ; Vu, V. A. Angew. Chem. , Int. Ed. 2003, 42, 4302 (review). (18) Kharasch, M. S. ; Fuchs, C. F. J. Am. Chem . Soc. 1943, 65, 504. (19) Gilman, H. ; Lichtenwalter, M. J. Am. Chem. Soc. 1939, 61, 957. and earlier (back to 1914) references cited therein. 20) Kharasch, M. S. ; Fields, E. K. J. Am. Chem. Soc. 1941, 63, 2316. mechanism involving an organoiron(I) intermediate, obtained by reduction of the Fe(III) precursor by the Grignard reagent, was suggested. The results of a few experiments carried out on a 30-40 mmol scale (Table 3) showed that such iron-catalyzed reactions would be useful in the synthesis of ole? ns, but a broader study to optimize them and to broaden the scope of their application was not undertaken. The coupling of vinylic Grignard reagents with alkyl halides is catalyzed also by Ag(I) salts. 8 Thus, cis-propenylmagnesium (21) Two later â€Å"historical notes†22,23 and two book chapters24,25 that dealt with the cross-coupling reactions of Grignard reagents with vinylic halides also did not cite the Kharasch/Fuchs paper. (22) Tamao, K. J. Organomet. Chem. 2002, 653 , 27. (23) Murahashi, S. -I. J. Organomet. Chem. 2002, 653, 27. (24) Kochi, J. K. Organometallic Mechanisms and Catalysis; Academic Press: New York, 1978; Chapter 14, Sections III and IV. (25) Hou, S. ; Negishi, E. -i. In Handbook of Organopalladium Chemistry; Negishi, E. -i. , Ed. , Wiley: New York, 2002; Vol. 1,Chapter III. 2. 6, pp 335408. As a historical note, the following quotation from this reference (p 335) is of interest: â€Å"Although the reaction of Grignard reagents with organic halides was shown to be catalyzed by various late transition metal compounds (the Kharasch reaction) in the 1950s, it was not until the early 1970s that the applicability of this catalytic method was extended to the cross-coupling involving alkenyl and aryl halides catalyzed by Ag, Fe and other late transition metals. † (26) (a) Kochi, J. ; Tamura, M. J. Am. Chem. Soc. 1971, 93, 1487. (b) Tamura, M. ; Kochi, J. Synthesis, 1971, 303. (27) Full papers: (a) Neumann, S. M. ; Kochi, J. K. J. Org. Chem. 1975, 40, 599. (b) Smith, R. S. ; Kochi, J. K. J. Org. Chem. 1976, 41, 502. (c) Reviews: ref 24. (d) Kochi, J. K. J. Organomet. Chem. 2002, 653, 11 (historical note). (28) (a) Whitesides, G. M. ; Casey, C. P. J. Am. Chem. Soc. 1966, 88, 4541. (b) Tamura, M. ; Kochi, J. J. Am. Chem. Soc. 1971, 93, 1483. 1602 Organometallics, Vol. 28, No. 6, 2009 Table 3. Alkenylation of Grignard Reagents using FeCl3 as Precatalyst (in THF)a R MgBr (amt, mmol) n-C6H13MgBr (40) CH2dCH(CH2)4MgBr (36) n-C6H13MgBr (40) a 1 R2Br (amt, mmol) CH2dCHBr (204) CH2dCHBr (102) CH3CHdCHBr (355) FeCl3 (amt, mmol) 0. 05 0. 05 0. 10 reacn temp,  °C 0 25 25 product (yield, %) n-C6H13CHdCH2 (83) CH2dCH(CH2)4CHdCH2 (64) n-C6H13CHdCHCH3 (67) (53/47 cis/trans mixture) Taken from: Synthesis 1971, 6, 303. Scheme 2 bromide reacted with methyl bromide in THF in the presence of an Ag(I) catalyst to give cis-butene-2, but a similar reaction of trans-propenylmagnesium bromide gave a 7:3 mixture of cisand trans-butene-2, respectively. 28b Apparently propenyl radicals were involved. A similar Grignard reagent based cross-coupling, ole? n synthesis in which a copper(I) catalyst was used was published by French workers. 9 Normant et al. reported that their reactions (e. g. , n-Bu(Et)CdCHI + i-PrMgCl in THF at -20  °C with a Cu(I) catalyst) proceeded with retention of con? guration. 29a For a reaction of CH3CHdC(CH3)MgCl with n-C3H7I in THF at 0  °C using CuI as catalyst, Linstrumelle reported that the coupling product obtained in 97% yield was 88% cis and 12% trans, while a similar reac tion of CH2dC(CH3)MgBr with trans-n-C6H13CHdCHI gave a 4:1 trans/cis product. 29b TheuseofNi(II)catalystprecursorsforGrignardreagent-vinylic halide cross-coupling was reported in 1972 by Corriu and Masse30 and by Tamao, Sumitani, and Kumada. 1 The French group found Ni(II) acetylacetonate to be the most effective catalyst precursor, while the Japanese group favored a bis(tertiary phosphine)NiCl2 catalyst precursor and, especially, chelating diphosphine complexes such as (Ph2PCH2CH2PPh2)NiCl2. Reactions carried out in diethyl ether at re? ux generally gave excellent yields. This procedure has been carried out commercially on an industrial scale in the preparation of p-chloroand p-tert-butylstyrene. 32 Finally, the last to be discovered at that time and the most versatile procedure for the cross-coupling of Grignard reagents (29) (a) Normant, J. F. Commercon, A. ; Cahiez, G. ; Villieras, J. Compt. ? rend. Hebd. Seances Acad. Sci. , Ser. C 1974, 278, 967. (b) Derguini? Boumechal, F. ; Linstrumelle, G. Tetrahedron Lett. 1976, 3225. (30) Corriu, R. J. P. ; Masse, J. P. J. Chem. Soc. , Chem. Commun. 1972, 144. (31) (a) Tamao, K. ; Sumitani, K. ; Kumada, M. J. Am. Chem. Soc. 1972, 94, 1375. (b) See also ref 22. Later work: (c) Tamao, K. ; Kiso, Y. ; Sumitani, K. ; Kumada, M. J. Am. Chem. Soc. 1972, 94, 9268. (d) Kiso, Y. ; Tamao, K. ; Kumada, M. J. Organomet. Chem. 1973, 50, C12. (e) Kiso, Y. ; Tamao, K. ; Miyake, N. ; Yamamoto, K. ; Kumada, M. Tetrahedron Lett. 974, (No. 1), 3. (f) Tamao, K. ; Sumitani, K. ; Kiso, Y. ; Zembayashi, M. ; Fujioka, A. ; Kodama, S. ; Nakajima, I. ; Minato, A. ; Kumada, M. Bull. Chem. Soc. Jpn. 1976, 49, 1958. (g) Tamao, K. ; Kodama, S. ; Nakajima, I. ; Kumada, M. ; Minato, A. ; Suzuki, K. Tetrahedron 1982, 38, 3347. (32) Banno, T. ; Hayakawa; Umeno, M. J. Organomet. Chem. 2002, 653, 288. (33) (a) Yamamura, M. ; Moritani, I. ; Murahashi, S. -I. J. Organomet. Chem. 1975, 91, C39. Full paper: (b) Murahashi, S. -I. ; Yamamura, M. ; Yanagisaw a, K. -i. ; Mita, N. ; Kondo, K. J. Org. Chem. 1979, 44, 2408. (c) Historical note: ref 23. ith vinylic and aryl halides, that catalyzed by palladium complexes, was reported by Shun-Ichi Murahashi and coworkers in 1975. 33a The reactions were carried out in diethyl ether/benzene at room temperature using (Ph3P)4Pd as the catalyst precursor, and they proceeded stereospeci? cally in excellent yield (Scheme 2). Dang and Linstrumelle also used this procedure to prepare 1,3-dienes stereospeci? cally by the reaction of vinylic iodides with vinylic Grignard reagents. 34 Palladium-catalyzed cross-coupling of Grignard reagents with organic halides has been a very active area in organic synthesis. Reference 25 reviews (up to 2002) its application in (alkenyl) MgX-ArX, ArMgX-(alkenyl)X, and (alkenyl)MgX-(alkenyl)X coupling processes. A further chapter in this book deals with ArMgX-Ar? X coupling. 35 Another surge of research activity on cross-coupling of Grignard reagents with organic halides started around the turn of the century and still appears to be in progress at the present time (January 2009). Interest has revived in the use of iron complexes as precatalysts for the cross- and homocoupling of Grignard reagents,36 since iron complexes are cheaper than those of palladium and are nontoxic. The iron-catalyzed cross-coupling of organomagnesium bromides with vinylic bromides, although it produced ole? ns in good yield, was of interest to Jay Kochi, as noted above, primarily from the point of view of its reaction mechanism rather than of its potential for application in organic synthesis. After some 25 years several research groups carried out much experimental work which has shown iron-catalyzed cross-coupling and homocoupling of Grignard reagents to be broadly applicable and very useful additions to the methods of organic synthesis. In 1995 Gerard Cahiez, at the Universite Pierre et Marie Curie ? ? in Paris, during the course of his extensive investigations of organomanganese chemistry, found that the cross-coupling of vinylic bromides with alkyl, vinylic, and phenylmanganese chlorides could be effected in good yield in the presence of 3 mol % of iron(III) acetylacetonate in a THF/N-methyl-2pyrrolidinone (NMP) mixed solvent at room temperature. 37 In a thorough study, this reaction was extended to the crosscoupling of vinylic halides with alkylmagnesium halides using 1 mol % of Fe(acac)3 and the same solvent mixture. 8 High yields of ole? nic products were obtained. Successful crosscoupling of Grignard reagents with AcO(CH2)6CHdCHCl, CH3C(O)(CH2)3CHdCHCl, Cl(CH2)4CBrdCH2, 9, and 10 are noteworthy as examples of the selectivity and functional group tolerance of this reaction. The scope of this chemistry was extended further when some of Knochel’s functionally substituted aryl Grignard reagents17 (vide supr a) were reacted with vinylic bromides and iodides. 39 The cross-coupling reaction between aryl Grignard reagents and vinylic bromides and iodides also was found by Cahiez and co-workers to give ole? ic products in good yield with Organometallics, Vol. 28, No. 6, 2009 1603 Table 4. Iron-Catalyzed Biaryl Coupling Reactions a Table 5. Iron-Catalyzed Homocoupling of Grignard Reagents with Atmospheric Oxygen as Oxidanta a Taken from: J. Am. Chem. Soc. 2007, 129, 13788. palladium or nickel precatalysts. 42 Of these procedures, that of Cahiez et al. 41f appears to be the most useful. Alkyl halide/ alkylmagnesium halide cross-coupling is not a practical process. 43 RMgX + R? X 9 R-R? + MgX2 8 [Fe] (8) Iron-catalyzed reactions of aryl Grignard reagents with aryl halides to give biaryls generally are not synthetically useful. The desired cross-coupling products are obtained in only poor yield, the main product being the homocoupled biaryl derived from the aryl Grignard reagent (eq 9) (recall the Gilman/ Lichtenwalter and Kharasch/Fields reactions, vide supra). ArMgX + Ar? X f Ar-Ar? + (low yield) (major Ar-Ar product) (9) a Taken from: J. Am. Chem. Soc. 2007, 129, 9844. retention of geometric con? guration when carried out in THF solution in the presence of 10 mol % of MnCl2. 0 As noted above, Kharasch and Fuchs had found that attempts to cross-couple aryl Grignard reagents with alkyl halides in the presence of catalytic amounts of CoCl2 were unsuccessful. On the other hand, such reactions do occur in the presence of an iron precatalyst and various additives (eq 8, R? ) alkyl), as summarized in ref 36. A number of other groups have reported the results of their research directed tow ard development of an effective procedure for the process shown in eq 8, all using an iron precatalyst of one kind or another, various additives such as TMEDA, NMP, etc. nd generally diethyl ether (but sometimes THF) as solvent. 41 It is noteworthy that primary and secondary alkyl halides, i. e. , ones that contain hydrogen substituents on the carbon atom, can be cross-coupled with aryl Grignard reagents, a process that cannot be realized using (34) Dang, H. P. ; Linstrumelle, G. Tetrahedron Lett. 1978, 191. (35) Anastasia, L. ; Negishi, E. -i. Chapter II. 2. 5, pp 311-344, in ref 25. (To date palladium and nickel catalysts have been widely used to effect aryl-aryl cross-coupling reactions. However, arylmagnesium halides were found to undergo cross-coupling with aryl halides that contain electron-withdrawing activating substituents ortho or para with respect to the halogen substituent in the presence of 10 mol % of manganese(II) chloride (eq 10). 44 Cyclohexyl and 2-methylpropenyl G rignard reagents reacted with such substituted halobenzenes in a similar manner. Very (36) (a) Cahiez, G. ; Duplais, C. â€Å"Iron-Catalyzed Reactions of Grignard Reagents†, Chapter 13, pp 594-630 in ref 16e. (b) Furstner, A. ; Leitner, ? A. ; Mendez, M. ; Kraus, H. J. Am. Chem. Soc. 2002, 124, 13856 (a long ? paper that brings an excellent discussion of the literature, of questions concerning mechanism, and original results). (c) Sherry, B. D. ; Furstner, ? A. Acc. Chem. Res. 2008, 41, 1500. (37) Cahiez, G. ; Marquis, S. Tetrahedron Lett. 1996, 37, 1773. (38) Cahiez, G. ; Avedissian, H. Synthesis 1998, 1199. (39) Dohle, W. ; Kopp, F. ; Cahiez, G. ; Knochel, P. Synlett 2001, 1901. 1604 Organometallics, Vol. 28, No. 6, 2009 Table 6. Manganese-Catalyzed Homocoupling of Grignard Reagents with Atmospheric Oxygen as Oxidanta Scheme 4 THF to a mixture of 3 mol % of FeF3  · 3H2O and 9 mol % of an N-heterocyclic carbene (SIPr  · HCl). In one example, chlorobenzene (1. 0 equiv) and p-CH3C6H4MgBr (1. 2 equiv) were added to this catalyst system and the reaction mixture was stirred at 60  °C for 1 day. The desired product, p-CH3C6H4-C6H5, was obtained in 98% yield. The homocoupling product, biphenyl, was present only in trace amount, while CH3C6H4C6H4CH3 was formed in 3% yield. Some examples of the application of this remarkable reaction are shown in Table 4. Good results were obtained only with aryl chlorides. Aryl bromides and iodides gave low biaryl yields. A German group reported similar MnCl2-catalyzed cross-coupling between various heterocyclic chlorides and aryl as well as alkyl Grignard reagents: e. g. , eq 11. 46 a Taken from: J. Am. Chem. Soc. 2007, 129, 13788. The homocoupling reaction of aryl Grignard reagents, mentioned earlier, also has received renewed attention recently, and synthetically useful procedures have resulted. Nagano and Hayashi developed a procedure in which the reaction is carried out in re? uxing diethyl ether in the presence of 1-5 mol % of FeCl3, NMP and 1. molar equiv of 1,2-dichloroethane (which serves as the oxidant). 47 Cahiez and co-workers have improved this procedure by using THF as solvent, in which arylmagnesium halides, including the chlorides, are more easily prepared. 48 This procedure works well with Knochel’s functional arylmagnesium halides (Scheme 3). Of interest also is the clever construction of the tricyclic system 11 by intramolecul ar homocoupling (Scheme 4). (40) (a) Cahiez, G. ; Gager, O. ; Lecomte, F. Org. Lett. 2008, 10, 5255. (b) Alami, M. ; Ramiandrasoa, P. ; Cahiez, G. Synlett 1998, 325. 41) A selection: (a) Martin, R. ; Furstner, A. Angew. Chem. , Int. Ed. ? 2004, 43, 3955 (see also ref 36b and references cited therein). (b) Nagano, T. ; Hayashi, T. Org. Lett. 2004, 6, 1297. (c) Bedford, R. B. ; Bruce, D. W. ; Frost, R. M. ; Goodby, J. W. ; Hird, M. Chem. Commun. 2004, 2822. (d) Nakamura, N. ; Matsuo, K. ; Ito, S. ; Nakamura, E. J. Am. Chem. Soc. 2004, 126, 3686. (e) Bedford, R. B. ; Bruce, D. W. ; Frost, R. M. ; Hird, M. Chem. Commun. 2005, 4161. (f) Cahiez, G. ; Habiak, V. ; Duplais, C. ; Moyeux, A. Angew. Chem. , Int. Ed. 2007, 46, 4364. g) Cahiez, G. ; Duplais, C. ; Moyeux, A. Org. Lett. 2007, 9, 3253. (h) Guerinot, A. ; Reymond, S. ; Cossy, J. Angew. ? Chem. , Int. Ed. 2007, 46, 6521. (42) However, Terao and Kambe have recently developed new Pd- and Ni-based precatalyst systems which avoid the pro blem of -elimination of primary and secondary alkyl groups: Terao, J. ; Kambe, M. Acc. Chem. Res. 2008, 41, 1545. (43) (a) Tamura, M. ; Kochi, J. J. Organomet. Chem. 1971, 31, 289. (b) Rollick, K. L. ; Nugent, W. A. ; Kochi, J. K. J. Organomet. Chem. 1982, 225, 279. (44) Cahiez, G. ; Lepifre, F. Ramiandrasoa, P. Synthesis 1999, 2138. (45) Hatakeyama, T. ; Nakamura, M. J. Am. Chem. Soc. 2007, 129, 9844. (46) Rueping, M. ; Ieawsuwan, W. Synlett 2007, 247. (47) Nagano, T. ; Hiyama, T. Org. Lett. 2005, 7, 491. (48) Cahiez, G. ; Chaboche, C. ; Mahuteau-Betzer, F. Org. Lett. 2005, 7, 1943. Scheme 3 special, but generally applicable, reaction conditions developed by Japanese workers45 have ? nally provided the possibility of clean aryl-aryl cross-coupling reactions in which competitive homocoupling of the aryl Grignard reagent has been almost completely suppressed. In this procedure an active catalyst system was prepared by addition of 18 mol % of C2H5MgBr in Organometallics, Vol. 28, No. 6, 2009 1605 A further improvement resulted when it was found that atmospheric oxygen could replace the 1,2-dihaloethane as oxidant in the homocoupling of aryl, vinylic, and alkynyl Grignard reagents using either Fe or Mn catalyst precursors. 49 As Tables 5 and 6 show, this procedure gave excellent results. The most recent contribution to iron-catalyzed cross-coupling, which appeared during the preparation of the ? al draft of this paper, involves application of the old one-pot Barbier procedure in which FeCl3 served as precatalyst and stoichiometric amounts of magnesium turnings and TMEDA additive were used. A mixture of an alkyl and an aryl bromide was added to the mixture of precatalyst, TMEDA, magnesium, and solvent at 0  °C. Good yields of cross-coupled products were obtained. 50 There has been a great deal of activity in the areas of Grignard reagent/o rganic halide cross-coupling and aryl Grignard reagent homocoupling, and the coverage in this essay, whose focus is on the historical aspects, is far from exhaustive. Attention is called to the 2005 review by Frisch and Beller51 and especially (49) Cahiez, G. ; Moyeux, A. ; Buendia, J. ; Duplais, C. J. Am. Chem. Soc. 2007, 129, 13789. (50) Czaplik, W. M. ; Mayer, M. ; von Wangelin, A. J. Angew. Chem. , Int. Ed. 2009, 48, 607. (51) Frisch, A. C. ; Beller, M. Angew. Chem. , Int. Ed. 2005, 44, 674. to the recent Accounts of Chemical Research special issue on cross-coupling. 52 Since ? st reported in 1943, the cross-coupling of Grignard reagents with organic halides, thanks to further development by many later workers, has become a broadly applicable, very useful reaction in organic synthesis. There is much more about Grignard reagents that I have not covered: the various procedures used in their preparation, the mechanism of their formation (which is still controversial), the more complex organomagnesium compounds such as bis(cyclopentadienyl)magnesium, magnesium butadiene, and magnesium anthracene, and the many kinds of reactions that Grignard reage nts have been reported to undergo. But this is only a short essay, and so I have been able to cover only a few selected topics, ones which I hope will be of interest to the reader. More information can be found in the books that I have cited earlier. 16 Acknowledgment. My thanks, as always, to Professor Arnold L. Rheingold for the cover ? gure. OM900088Z (52) Acc. Chem. Res. 2008, 41, No. 11, 1439-1564, special issue. A collection of 11 reviews, many of them relevant to the subject matter of the present essay, with useful, up-to-date references. How to cite Grignard Reagent, Papers