A Practical, One-Pot Multicomponent Synthesis of α-Amidosulfides and Their Application as Latent N-Acylimines in the Friedel-Crafts Reaction

A novel one-pot, three-component synthesis of N-acyl or N-carbamoyl-alpha-amidosulfides 4 is described. The three-component reaction of aldehydes 1, primary carbamates (or amides) 2 and phenylsulfinic acid (6a) afforded alpha-amidosulfones 7, which after addition of sodium thiolate were in situ transformed into stable alpha-amidosulfides 4 in good to excellent yields. We demonstrated that silver salts or Bronsted acids were able to promote the formation of aliphatic and aromatic N-acylimines from 4 in quantitative yield under mild conditions. The phosphoric acid catalyzed Friedel-Crafts alkylation of 3-substituted indoles with alpha-amidosulfides 4 leading to 2,3-disubstitued indoles was also documented.