Three-component coupling reactions of thioformamides with organolithium and Grignard reagents leading to formation of tertiary amines and a thiolating agent

A highly efficient three-component coupling reaction between thioformamides and organolithium and Grignard reagents was developed. The generality of the process has been demonstrated by using various combinations of reactants and reagents. Information about the mechanism of the reaction has come from H-1 and C-13 NMR spectroscopic detection of the key intermediate. The LiS group in the intermediates generated by addition of the organolithium reagents to the thioformamides serves as a leaving group. The solid byproduct formed in these reactions, formulated as [LiSMgBr], can be used as a thiolating agent to transform acid chlorides into thioic acids and thioic acid anhydrides.