Energy Transfer Catalysis Enabled 2,2,2‐Trifluoroethoxy‐Amination of Olefins

Abstract

A thioxanthone‐catalyzed 2,2,2‐trifluoroethoxyamination of olefins is developed via the formation of the corresponding alkoxy and iminyl radicals using unprecedented, easily prepared, and bench‐stable oxime ethers as bifunctional reagents. To bypass possible side reactions (1,2‐Hydrogen Atom Transfer (HAT), H‐abstraction, and β‐scission), the high reactivity of the alkoxy radical is fine‐tuned to promote the selective and challenging formation of a COCH2CF3 bond. This reaction, involving a triplet energy transfer process, allows the concomitant formation of a CN and COAlk bond, so far uncharted, using bifunctional oxime ether reagents. Hence, the difunctionalization of a myriad of electron‐rich alkenes selectively afforded the anti‐Markovnikov products with a large functional group tolerance (44 examples, up to 77% yield), offering a straightforward and complementary regioselectivity compared to the existing approaches for the difunctionalization of alkenes with 2,2,2‐trifluoroethanol. Post‐functionalization reactions and mechanistic investigations provided key insights into the reaction mechanism of this transformation.

Keywords

• alkoxy radical generation
• bifunctional reagents
• energy transfer
• photocatalysis
• 2,2,2‐trifluoroethoxyamination reactions