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

Abstract

Iodomethylthiobenzoate 5 and α-chloroalkyl phenyl sulfides 6 were found to insert zinc dust in THF under very mild conditions (10–25 °C, 0.5–2 h) leading to zinc α-thioorganometallics. After a transmetallation with CuCN·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 α-thiocarbanions, these zinc-copper reagents can bear various functional groups like esters or nitriles. The same approach allowed the preparation of various γ-thio-substituted zinc and copper reagents bearing phenylthio, phenylsulfinyl, or α-(phenylsulfonyl)vinyl functionalities ( 20–22) which also display a good ability to form new carboncarbon bonds.