Photochemical substitution of olefins and aromatic compounds with difluoromethyl radicals bearing ester and phosphonate groups

Efficient and selective substitution of cyclic and acyclic vinyl ethers with photo-generated difluoromethyl radicals bearing ester and phosphonate groups, in the presence of 2,4,6-trirnethylpyridine and diphenyl diselenide was successfully carried out to provide the corresponding regioselective unsaturated difluoromethylene adducts selectively. The reaction involves phenylselenyl transfer at an early stage followed by elimination of phenylselenol from the adducts once formed to provide the unsaturated difluoromethylene adducts selectively. This novel photochemical method was successfully extended to aromatic and heteroaromatic substitutions to provide the corresponding alpha-aryl-alpha,alpha-difluoroacetates and alpha-aryl-alpha,alpha-difluoromethyl phosphonates in good to moderate yields. (9) 2006 Elsevier Ltd. All rights reserved.