Hydrochloric Acid → 8-Chloro-1-methyl-1,4-dihydro[1]benzothiopyrano[4,3-c]pyrazole

Participants

Reaction Steps

A solution of hydrogen chloride in methanol (225 ml) was added to a suspension of 3-(2-t-butoxycarbonyl-2-methylhydrazinomethylene)-6-chloro-2,3-dihydro-4H-1-benzothiopyran-4-one (54.14 g) in methanol (550 ml). After being stirred at ambient temperature for 8 hours, the mixture was evaporated in vacuo and the residue was extracted with ethyl acetate after an addition of water. The extract was washed with aqueous sodium bicarbonate and then water, dried over magnesium sulfate, and evaporated in vacuo to give 8-chloro-1-methyl-1,4-dihydro[1]benzothiopyrano[4,3-c]pyrazole (26.63 g).

Provenance & Evidence