Sequential C-F bond functionalizations of trifluoroacetamides and acetates via spin-center shifts.

Science

Hefei National Laboratory for Physical Sciences at the Microscale, Department of Chemistry, University of Science and Technology of China, Hefei, Anhui 230026, China.

Published: March 2021

Defluorinative functionalization of readily accessible trifluoromethyl groups constitutes an economical route to partially fluorinated molecules. However, the controllable replacement of one or two fluorine atoms while maintaining high chemoselectivity remains a formidable challenge. Here we describe a general strategy for sequential carbon-fluorine (C-F) bond functionalizations of trifluoroacetamides and trifluoroacetates. The reaction begins with the activation of a carbonyl oxygen atom by a 4-dimethylaminopyridine-boryl radical, followed by a spin-center shift to trigger the C-F bond scission. A chemoselectivity-controllable two-stage process enables sequential generation of difluoro- and monofluoroalkyl radicals, which are selectively functionalized with different radical traps to afford diverse fluorinated products. The reaction mechanism and the origin of chemoselectivity were established by experimental and computational approaches.

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http://dx.doi.org/10.1126/science.abg0781DOI Listing

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