Stoichiometric versus Catalytic Use of Copper(i) Salts in the Synthetic Use of Main Group Organometallics

We review some applications of copper derivatives as synthetic tools: stoichiometric organocopper reagents and organomagnesium derivatives in the presence of catalytic amounts of copper salts are able to give a regioselective addition on to acetylenic substrates and to alkylate alkyl or vinyl halides, bromohydrines, their tosylates and carboxylates, and a large variety of allylic substrates. INTRODUCTION Organocopper chemistry has been developping tremendously these last ten years, mainly because of the selectivity and the velocity of the reaction processes, even at low temperatures, two important factors to be considered when dealing with complex and fragile molecules. I shall endeavour to compare the possible uses of organocoppe reagents, organocuprate reagents and Grignards in the presence of a catalytic amount of Cu salt, first in the field of addition to unactivated CC bonds, and second, in the field of alkylation of various electrophiles: organic halides, acetates, ethers... These reagents allow reactions that Grignard alone would not be able to promote, but many parameters have to be settled accurately: temperature, solvent, presence of sulfur-, nitrogen-, phosphorous-, halogen-derived ligands. A clear survey of the respective influence of these factors cannot be drawn by this time. Organocopper species are derived, in practice, from Organomagnesiumor lithium reagents: 1 CuX RCu,MX Organocopper reagcnt or RCuX,M alkyl heterocuprate