NHC-catalyzed Enantioselective Hetero-[10+2] Annulation

Abstract

The higher-order cycloadditions are powerful strategies for construction of polycycles in one step, however an efficient and concise version for asymmetric induce is limited. N-heterocyclic carbenes are widely used organocatalysts for asymmetric synthesis and will be an ideal choice for enantioselective higher-order cycloadditions. Here we report an enantioselective [10+2] annulation between catalytically formed aza-benzofulvene intermediates and trifluoromethyl ketone derivatives. This protocol exhibits a wide scope, high yields and good ee values, reflecting a robust and efficient higher-order cycloaddition. Density functional theory (DFT) calculations provided an accurate prediction of the reaction enantioselectivity, and in-depth insight to the origins of stereocontrol.

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