Ethyl chloroformate → HCID 68826227, compound

Participants

Reaction Steps

To an ice-cooled suspension of 3-amino-1H-thieno[3,2-c]pyrazole-5-carboxylic acid methyl ester (35.5 mmol, 7.0 g) and N,N′-diisopropylethylamine (0.21 mol, 36.5 mL) in 71 mL of tetrahydrofuran were added, dropwise, 3.5 mL of ethyl chloroformate (36.6 mmol). After 1.5 hours, the cold suspension was concentrated under vacuum and diluted with dichloromethane. The organic phase was washed with buffer pH 4, sodium hydroxide 1 N, brine and dried over Na2SO4. The filtrate was evaporated to dryness and triturated with dichloromethane to give 6 g 1-ethyl 5-methyl 3-amino-1H-thieno[3,2-c]pyrazole-1,5-dicarboxylate (7)

Provenance & Evidence