PROBLEM TO BE SOLVED: To provide a production method of α-heterocyclyl acetic acid compound which uses an α,&bgr;-unsaturated carboxylic acid as a raw material and is useful as an intermediate for synthesis of medicines.SOLUTION: A production method of α-heterocyclyl acetic acid compound comprises converting an α,&bgr;-unsaturated carboxylic acid compound of formula (1) into a compound of formula (2) in the presence of phenylboronic acid and a tertiary amine having a hydrogen bond donating part within the molecule. In formulae (1) and (2), n is 1 or 2; Rand Rare H, a halogen atom, an optionally substituted 1-8C alkyl group or an optionally substituted phenyl group; Rand Rmay bind to each other to form an optionally substituted benzene ring; ** represents an asymmetric carbon atom.
