Photocatalyzed Formation of gem‐Difluoroalkenes Using Oxime Esters

In this manuscript a general photocatalytic approach for the synthesis of alkyl‐substituted gem‐difluoroalkenes using readily available oxime esters and 1‐bromo‐1,1‐difluoroprop‐2‐ene (BDFP) has been established. This strategy involving a radical bromo elimination provides access to a large variety of value‐added fluorinated molecules. The mild reaction conditions are compatible with many functional groups including complex natural products or drug molecules. Experimental and theoretical mechanistic investigations indicate that the efficiency of the process relies on the crucial role of imine radical, which is formed after photoexcitation via energy transfert (EnT) and decarboxylation of the oxime ester. Indeed, the imine radical would either behave as a bromine radical scavenger or an XAT promoter in this reaction.