To selectively obtain an α-chloroketone compound in a high yield by subjecting an alkynylamide to a ring formation by using a catalytic amount of a metal salt, then reacting the resultant substance with trichloroisocyanuric acid to produce a chlorinated oxazoline intermediate and hydrolyzing the compound with an aqueous acid.

An alkynylamide of formula I [Z is a (substituted) alkyl, a (substituted) aryl, a (substituted) heteroaryl or phenylene; R is H or an alkyl; R1 and R2 are each a (substituted) alkyl or R1 and R2 are bonded to form a ring with carbon bonded to them] is subjected to a ring formation by using a catalytic amount of a metal salt in the presence of an organic solvent to form a 5-methyleneoxazoline of formula II. The 5-methyleneoxazoline of formula II is chlorinated with trichloroisocyanuric acid in a solvent to produce a chlorinated oxazoline intermediate of formula III, which is hydrolyzed with an aqueous acid to produce an α-chloroketone of formula IV.