Synthesis of Trifluoromethyl-Substituted Allenols via Catalytic Trifluoromethylbenzoxylation of 1,3-Enynes

Abstract

Allenol has been identified as a versatile building block for organic synthesis, and numerous efforts have been made to synthesize and apply allenol. However, limited efforts have been made to obtain a trifluoromethyl-substituted allenol. Here, by using a readily available 1,3-enyne as the starting material, a copper-catalyzed trifluoromethylbenzoxylation process was developed for efficient synthesis of trifluoromethyl-substituted allenols using Togni-II reagent as the reaction partner. Triple roles of the Togni-II reagent, including as the source of the trifluoromethyl group, as the source of the hydroxyl group, and as the oxidant, were elucidated in this transformation. Moreover, late-stage diversification was performed, which revealed the application potential of trifluoromethyl-substituted allenols for the preparation of various trifluoromethyl-substituted compounds.