Domino Michael addition-carbene rearrangement-cyclization reaction of 1-alkynyl(aryl)-(lambda)^3-bromanes with 2mercapto-1,3-benzazoles

Exposure of 1-alkynyl[p-(trifluoromethyl)phenyl](tetrafluoroborato)-(lambda)^3-bromanes to 2-mercaptobenzimidazole or benzothiazole in dichloromethane at 0 °C under argon resulted in a domino Michael addition–carbene rearrangement–cyclization reaction to produce directly tricyclic heterocycles in high yields, whereas the reaction with 2-mercaptobenzoxazole afforded 1-alkynyl sulfides.