Organometallic compounds with alkyl halides

Rauhut, M.M. and Semsel, A.M., Reactions of elemental phosphorus with organometallic compounds and alkyl halides. The direct synthesis of tertiary phosphines and cyclotetraphosphines, J. Org. Chem., 28, 473, 1963. 

Coupling of Organometallic Compounds with Aryl Halides, Ethers, and Carboxylic Esters Alkyl-de-halogenation. etc. 

The properties of organometallic compounds are much different from those of the other classes we have studied to this point Most important many organometallic com pounds are powerful sources of nucleophilic carbon something that makes them espe cially valuable to the synthetic organic chemist For example the preparation of alkynes by the reaction of sodium acetylide with alkyl halides (Section 9 6) depends on the presence of a negatively charged nucleophilic carbon m acetylide ion... 

Mechanistically the reaction can be divided into two steps. Initially the alkyl halide 1 reacts with sodium to give an organometallic species 3, that can be isolated in many cases. In a second step the carbanionic R of the organometallic compound 3 acts as nucleophile in a substitution reaction with alkyl halide 1 to replace the halide ... 

It might be mentioned that matters are much simpler for organometallic compounds with less-polar bonds. Thus Et2Hg and EtHgCl are both definite compounds, the former is a liquid and the latter is a solid. Organocalcium reagents are also known, and they are formed from alkyl halides via a single electron transfer (SET) mechanism with free-radical intermediates. "... 

A variety of organometallic compoundshave been used to couple with alkyl halides. " Organosodium and organopotassium compounds are more reactive than Grignard reagents and couple even with less reactive halides. Organolithium... 

Development of new methodologies for formation of carbon-carbon bonds has been one of the major tasks in organic chemistry. Obviously, organometallic compounds, particularly zinc derivatives, have found great use in such reactions. During the past several years, there have been several significant reports of nickel- and palladium-catalyzed reactions of dialkylzincs and alkylzinc halides with alkyl halides of diverse structure. A detailed account of most of these studies can be found in a recent review by Knochel et al,246... 

The Conversion of Acyl Halides to Ketones with Organometallic Compounds 632 Alkyl-de-halogenation... 

Electrochemical or Li-benzophenone reduction of Fe(Pc) and Co(Pc) gives [M Pc] and [M (Pc)]2. 198,199 These monovalent metal complexes react with alkyl halides to give organometallic compounds which transfer the alkyl group to alkenes in the presence of Pd11 salts (Scheme 61). [Co PCTS]5- and [Co PCTS]6- reductively bind one and two molecules of oxygen respectively in DMF,198 The second 02 addition is reversible (Scheme 62). 

Anyway, it is doubtful whether Letts and Collie thought about zinc as the catalyst of the reaction of tin with alkyl halides (in spite of their demonstration) since this fact was established considerably later. The authors also found that the reaction of EtI with a Sn—Zn alloy (33-50%) containing 5% of Cu gave a maximum yield of E Sn. Thus, long before Rochows s finding the catalytic influence of copper in the direct synthesis of organometallic compounds was observed636. 

We have already encountered one type of organometallic compound with a negative charge on carbon sodium acetylides, covered in Section 9-7. Terminal alkynes are weakly acidic, and they are converted to sodium acetylides by treatment with an unusually strong base, sodium amide. These sodium acetylides are useful nucleophiles, reacting with alkyl halides and carbonyl compounds to form new carbon-carbon bonds. 

Like magnesium, lithium reacts with alkyl halides, vinyl halides, and aryl halides to form organometallic compounds. Ether is not necessary for this reaction. Organolithium reagents are made and used in a wide variety of solvents, including alkanes. 

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