Regioselectivity in Photochemical Chlorocarbonylation of Carbonyl Compounds

Article abstract of DOI:10.1021/jo00087a033

Photochemical chlorocarbonylation of a series of cyclic and acyclic carbonyl compounds shows remarkable regioselectivity and gives β- or γ-substituted products in reasonable yields.Irradiation of cyclopentanone in oxalyl chloride followed by esterification with methanol gave methyl 3-oxocyclopentanecarboxylate (4).Similarly, photochemical chlorocarbonylation of cyclobutanone yielded methyl 3-oxocyclobutanecarboxylate (6).Application of the chlorpcarbonylation reaction to 3-pentanone gave methyl 4-oxohexanoate (8) and dimethyl 4-oxopimelate (9).When a mixture of 3-methylbutanoic acid and oxalyl chloride was irradiated, dimethyl 3-methylglutarate (11) was obtained after methanolysis.A kinetically-controlled mechanism for the photochemical process was deduced.