5-Mercaptotetrazoles as Synthetic Equivalents of Nitrogen-Contaning Functional Groups. The Case of the Organocatalytic Enantioselective aza-Michael Reaction

5-Mercaptotetrazoles have been identified as useful and versatile Michael donors in enantioselective amine-catalyzed aza-Michael reactions with alpha,beta-unsaturated aldehydes, showing excellent behavior as N-nucleophiles instead of their usual trend to react as S-nucleophiles. In addition several unprecedented chemical modifications on the tetrazolothione moiety have been carried out leading to the enantioselective preparation of different compounds incorporating nitrogen-containing functionalities such as oxazinimines, formamidines, ureas and isoureas.