Rearrangement of the Breslow intermediate

by McIntosh, Matt; Ayinuola, Kolawole; Alwarsh, Sefat

In 1958 Ronald Breslow proposed intermediate 3 during investigations into the mechanism of thiamine pyrophosphate (1) catalyzed reactions. Since then, the eponymous intermediate has been invoked to explain a wide variety of N-heterocyclic carbene catalyzed reactions of aldehydes. We recently reported that the intermediate could be intercepted in a Claisen-like rearrangement under mild conditions to provide C2-substituted benzothiazoles 4. In this presentation, we will discuss the results of mechanistic studies about the rearrangement and details of another unexpected rearrangement of the Breslow intermediate.