Copper reaction with alkyl halides

The tosylate group can be displaced from alkyl tosylates by dialkyl-cuprates 256, 297, 301), presumably by attack at carbon by the d electrons of copper. A transient copper(III) intermediate may be formed [Eq. (87)], as suggested for similar reactions with alkyl halides. An analogous reaction was reported between a copper(I) carboxylate and an alkyl tosylate 185). (Carboxyethyl)methylcopper, C2H5O2CCH2CU, failed to react with butyl tosylate in THF 181). However, copper compounds of the type RCu are generally less reactive than the cuprates. 

With PCI3, Cu atoms yielded smaller amounts of product. Copper also proved useful in dehalogenation reactions with alkyl halides ... 

Because of the solubility of copper cyanide in l-methyl-2-pyrrolidone the latter has been recommended447 as solvent for the reaction with alkyl halides. 

Reactions with cyclopropene.11 Lithium organocuprates react with the cyclo-propenone ketal 1 (12, 152-154) to form a copper species (a) that behaves as an enolate of a cyclopropanone. Thus it reacts with alkyl halides to form cis-2,3-disubstituted derivatives of 1. 

Heavy-metal salts, particularly those of silver, mercury, and copper, catalyze SX1 reactions of alkyl halides in much the same way that acids catalyze the SN reactions of alcohols. A heavy-metal ion functions by com-plexing with the unshared electrons of the halide, thereby making the leaving group a metal halide rather than a halide ion. This acceleration of the rates of halide reactions is the basis for a qualitative test for alkyl halides with silver nitrate in ethanol solution ... 

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. 

A noticeable feature of the majority of reactions of diorganocuprates with alkyl halides (Table VI) is that molar ratios of up to 5 1, respectively, are employed for most effective coupling. However, good yields of coupled products can be obtained when molar equivalents of the reactants are used, a useful procedure for the more exotic copper... 

It was thought originally that in these complexes, the main bond was that formed between the copper atom and the carboxylate ion, the bonds existing with the amino group being auxiliary. It is now considered, however, that all the bonds, whether to oxygen or nitrogen atoms, are identical. This is evident since the reaction of the silver salts of the amino acids with alkyl halides results in the formation not only of the ester but also of the N-alkyl compound,... 

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