Preparation and Reactions of Functionalized Benzylic Organometallics of Zinc and Copper.

The reaction of zinc dust with primary or secondary benzylic halides 1 bearing various functional groups such as an ester, halide, cyano, or even a ketone group, in THF or, in the case of benzylic chlorides, in THF:DMSO (4:1), furnishes the corresponding zinc organometallics 2 in high yields. The reaction is accompanied by less than 10% of Wurtz coupling products. The benzylic copper organometallics 3, obtained after a transmetalation of 2 with the THF-soluble copper salt CuCN•2LiCl at −20 o C, react in excellent yields (70-95%) with various electrophiles such as acid chlorides, enones, aldehydes, allylic bromides, ethyl propiolate, and tributyltin chloride