The α-Chlorination of Aryl Ketones with Manganese(III) Acetate in the presence of Chloride Ion

Article abstract of DOI:10.1246/bcsj.58.142

The reaction of 2-(4-methoxyphenyl)-4-chromanone with Mn(OAc)3 in the presence of LiCl gave 3,3-dichloro-2-(4-methoxyphenyl)-4-chromanone.The reactions of 2-phenyl-4-chromanone, 1-phenyl-1-propanone, 1,2-diphenylethanone, and 1-tetralone similarly yielded α,α-dichloro derivatives in good yields. 2,2,2-Trichloroacetophenones were obtained from 2,2-dichloroacetophenones, but in the absence of LiCl, 2,2-dichloroacetophenones gave 2,2,3,3-tetrachloro-1,4-butanediones.KCl, NaCl, NH4Cl,AlCl3, and CaCl2 were also employed as the Cl^- ion source.Synthetic applicability and the reaction mechanisms are discussed briefly.