PURPOSE: To obtain a threo substituted-propionic acid derivative which is a synthetic intermediate for anti Ca2+ coronary circulatory enchancers, etc. in high yield in a short time, by reacting a novel tin 2-nitrothiophenol complex compound with a specific glycidic ester.

CONSTITUTION: A compound of formula II is reacted with a compound of formula III (X is halogen or aliphatic acyloxy ; y is 4 or 2) to give a novel compound of formulaI(x is 0, 1 or 2). The reaction is carried out in a solvent, e.g. benzene, at -30W+60°C. The resultant compound is then reacted with a trans-3- (4-methoxyphenyl)glycidic ester of formula IV (R is ester residue) to give a threo substituted -propionic acid derivative of formula V. The reaction is carried out in a solvent, e.g. benzene, at 0W60°C usually within 10min. The resultant compound of formula V is useful as a synthetic interemediate for diltiazem hydrochloride.