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 °C, react in excellent yields (70-95%) with various electrophiles such as acid chlorides, enones, aldehydes, allylic bromides, ethyl propiolate, and tributyltin chloride, leading to the polyfunctional molecules of type 4.