Mechanism of the Gold-Catalyzed Rearrangement of(3-Acyloxyprop-1-ynyl)oxiranes: A Dual Role of the Catalyst

摘要

The three competing paths for the rearrangement of 1 (involving 1,2- and 1,3-ester migration with alkyneor oxirane activation) evidence the multifaceted character of gold as a catalyst. The most favorablemechanism for this useful synthetic transformation involves a cascade of more than eight steps. All thefunctional groups in the substrate play a crucial and synergistic role, and sequential gold coordination toboth the π-system and the lone pairs of oxygen is needed. Exploration of these three paths suggests theuse of a nonalkynophilic Lewis acid (BF_3) as a possible synthetic alternative for this transformation.