Formaldehyde → 5-dimethylaminomethyl-5,6-dihydro-4H-thieno[2,3-b]thiopyran-4-one hydrochloride

Participants

Reaction Conditions

Reaction Steps

A mixture of 18 g of dimethylamine hydrochloride and 18 g of 37% formalin is stirred for 30 minutes and the temperature of the mixture is raised to 70° C. To the mixture is added 80 ml of acetic anhydride dropwise for 20 minutes at 70°-80° C. and kept for about 20 minutes at the same temperature. To the mixture is added 32.6 g of 5,6-dihydro-4H-thieno[2,3-b]thiopyran-4-one. The mixture is kept for 4 hours at the same temperature and then the solvent is distilled off under reduced pressure. To the residue is added acetone, and the precipitated crystals are collected by filtration and recrystallized from a mixed solvent of ethanol and isopropyl ether to give 35 g of 5-dimethylaminomethyl-5,6-dihydro-4H-thieno[2,3-b]thiopyran-4-one hydrochloride as white crystals, melting at 163°-166° C.

Provenance & Evidence