Chemoselective entry to 5-mercaptotriazoles by condensation of acetylenic esters with triphenylphosphine

A new kind of 1,2,4-triazol derivatives containing ylide moiety were designed and synthesized. The reaction is performed by condensation of dialkyl acetylenedicarboxylate with 5-aryl-2H-1,2,4-triazol-3-thiol in the presence of Ph3P. In these cases, the reactions take place on the sulfur atom in good to excellent yields via a chemoselective manner.