Cycloaddition of Aroyl/Acylketene<i>S,N</i>-Acetals with Tosyl Azide: Synthesis of Novel 4-Aroyl/Acyl-5-amino-1<i>H</i>-1,2,3-triazoles and 3,4-Annulated 1,2,3-Triazoles

Abstract

Cycloaddition of aroyl- and acylketene S,N-acetals 1a-l with tosyl azide 2 under alkaline conditions affords novel regiospecifically substituted 4-aroyl/acyl-1-phenyl/alkyl-5-tosylamino-1H-1,2,3-triazoles 5a-1. Some of them (5a-e, g, h) are shown to undergo facile detosylation in the presence of concentrated sulfuric acid to give the corresponding 5-aminotriazoles 6a-e, g, h in excellent yields. The reaction of cyclic S,N-acetals 8a-c with 2 in dioxane at higher temperature yields the corresponding bicyclic 3-aroyl-5,6-dihydrothiazolo[3,2-c] [1,2,3]-triazoles 10a-c in good yields.