Regioselective Formation of 2,4,5-Trisubstituted Oxazoles through Transition-Metal Free Heterocyclization of 1,3-Diynes with N,O-Bis(trimethylsiyl)acetamide

Transition-metal free heterocyclization reaction of 1,3-diynes with N,O-bis(trimethylsiyl)acetamide was accomplished in the presence of t-BuOK and acetonitrile at 120 degrees C. This method regioselectively gave 2,4,5-trisubstituted oxazoles in yields up to 97%.