PURPOSE: To obtain the titled compound useful as an antispasmodic and an antipeptic ulcer simply in high yield, by dehydrating di-(2-thienyl).(N-methyl-5- methoxy-3-piperidyl)carbinol.methobromide.

CONSTITUTION: A novel compound shown by the formula I is dehydrated in the presence of a small amount of a mineral acid (e.g., hydrochloric acid, hydrobromic acid, sulfuric acid, etc.), preferably a diluted solution of the acid under heating at 50W80°C, to give di-(2-thienyl).(N-methyl-5-methoxy-3-piperidylidene. methobromide shown by the formula II. The compound shown by the formula I is obtained easily by quaternizing a corresponding carbinol compound with methyl bromide.

EFFECT: Operations such as neutralization of acid, extraction, distillation, etc. after the reaction are not required at all.