(4-Chlorophenyl)hydrazine → 2-(4-chlorophenyl)-4,4a, 5,6-tetrahydrothieno[2',3':2,3]thiopyrano[4,5-c]pyridazin-3(2H)-one

Participants

Reaction Steps

A mixture of 4.0 g of 4-oxo-5,6-dihydro-4H-thieno-[2,3-b]thiopyran-5-acetic acid and 3.3 g of 4-chlorophenylhydrazine in 70 ml of ethanol is refluxed under heating for 6.5 hours. After cooling, the reaction mixture is concentrated under reduced pressure. The residue is dissolved in 50 ml of acetic acid and the solution is refluxed under heating for 2 hours. Then, the resultant mixture is concentrated under reduced pressure, the residue is subjected to chromatography on silica gel and eluted with chloroform. The crystals obtained from the fraction are recrystallized from a mixed solvent of chloroform and ethanol to give 4.3 g of 2-(4-chlorophenyl)-4a,5-dihydro-2H-thieno[2',3':2,3]thiopyrano[4,5-c]pyridazin-3(4H)-one as pale brown crystals, melting at 162°-164° C.

Provenance & Evidence