Photolysis of methyl 2-chloro-3-oxobutanoate

Abstract

Irradiation of methyl 2-chloro-3-oxobutanoate (I) in 50% ethanol yielded methyl 3-oxobutanoate, 2-methyl-2-pentanol-4-one, 2,5-dioxohexane-3,4-dicarboxylic acid dimethyl ester, 4-hydroxy-4,5-dimethyltetra-hydrofuran-2-one, 2,4-dimethylfuran-3,5-dicarboxylic acid dimethyl ester, 2,4-dimethyl-3-acetyl-2,3-dihydrofuran-3,5-dicarboxylic acid dimethyl ester and 1,4-dimethyl-6-acetyl-3,5,6-trimethoxycarbonyl-2-oxabicyclo[3.1.0]hex-3-ene.

The photolysis of I involved homolytic cleavage of the CCl bond, α-cleavage and α-elimination of hydrogen chloride, the last step resulting in the intermediate formation of carbomethoxyacylcarbene.

A possible route for the formation of the reaction products is discussed.