Direct 1,6-Difluoromethylation of 3-Methyl-4-nitro-5-styryl Isoxazoles by Photoredox-Promoted Radical Addition

Abstract

The photoredox-catalyzed 1,6-difluoromethylation of 3-methyl-4-nitro-5-styrylisoxazole with HCF2SO2Na has been developed. Structurally diverse difluoromethylated products were obtained in good yields, and their further transformations were also investigated. The di-, tri-, and monofluoromethylation of the substrates were compared, and the yield of the difluoromethylation was the highest. DFT calculations revealed that in the difluoromethylation reaction the CF2H radical was nucleophilic, and the transition state activation energy was the lowest.

Photocatalytic Cyclization Cascades by Radical Relay toward Pyrrolo[1,2-a]indoles: Synthesis, Mechanism, and Application

“…In order to further verify the applicability of the strategy and considering the significance of difluoromethylation, − a variety of unactivated N -alkene-linked indoles 1 were performed in the reaction of CHF 2 SO 2 Na 2b under standard conditions. As illustrated in Scheme , N -alkene-linked indoles with different substituents were suitable in this transformation to access difluoromethylated pyrrolo­[1,2- a ]­indoles 6a – 6f .…”