Thionyl Chloride → 6,7-Dihydro-1-benzothiophen-5(4H)-one

Participants

Reaction Steps

4-(2-Thienyl)butyric acid was reacted with thionyl chloride and stannic chloride to provide 5-oxo-4,5,6,7-tetrahydrobenzothiophene, which upon reaction with hydrazine and sodium hyroxide gave 4,5,6,7-tetrahydrobenzothiophene. A solution of 13.3 g of 4,5,6,7-tetrahydrobenzothiophene in 150 ml of dichloromethane was added dropwise to a stirred suspension of 13.1 g of ethyl oxalyl chloride and 14.0 g of aluminum chloride in 200 ml of dichloromethane. The reaction mixture was stirred for twelve hours at 25° C. following the addition. The reaction mixture was poured into 500 g of ice and then the organic layer was separated, dried, and the solvent was removed by evaporation to give 19.2 g of ethyl α-oxo-α-(4,5,6,7-tetrahydro-2-benzothienyl)acetate.

Provenance & Evidence