Preparation and Reactivity of Polyfunctional Zinc and Copper Organometallics Bearing Sulfur Functionalities

Abstract

Iodomethylthiobenzoate 5 and [alpha]-chloroalkyl phenyl sulfides 6 were found to insert zinc dust in THF under very mild conditions (10-25 [deg]C, 0.5-2 h) leading to zinc [alpha]-thioorganometallics. After a transmetallation with CuCN[middle dot]2 LiCl, the corresponding copper reagents 8 and 7 reacted with various electrophiles (1-haloalkynes, aldehydes, enones, acyl chlorides, allylic halides, trialkyltin halides) affording polyfunctional thioesters and sulfides of type 9 or 10 in excellent yields. Of special interest is that, contrary to lithium [alpha]-thiocarbanions, these zinc-copper reagents can bear various functional groups like esters or nitriles. The same approach allowed the preparation of various [gamma]-thio-substituted zinc and copper reagents bearing phenylthio, phenylsulfinyl, or [alpha]-(phenylsulfonyl)vinyl functionalities (20-22) which also display a good ability to form new carbon---carbon bonds.