NEW MATERIAL:N-(2-Dimethylaminoethyl)-N-(o-mercaptophenyl)-p-methoxy-α- acetoxycinnamic acid amide shown by the formula I and its acid addition salt.

USE: Useful as an intermediate for synthesizing a benzothiazepine derivative. The compound is useful as an antidepressives, tranaquilizer, coronary vasodilator, etc.

PREPARATION: A compound shown by the formula II (X is OH, or halogen) or 2-N-(2-dimethylaminoethyl)aminothiophenol shown by the formula III are subjected to a condensation reaction through dehydration or dehydrohalogenation reaction, to give a compound shown by the formula I. The condensation reaction through dehydration is carried out in an aprotic solvent in the presence of a condensation agent such as N,N'-dicyclohexylcarbodiimide, etc., at -20W50°C, and the dehydrohalogenation is done in an aprotic solvent in the presence of a base preferably pyridine, etc., at -30W50°C.