Diethyl 2-[(3-methylisothiazol-5-ylamino)methylene]malonate → Ethyl 3-methyl-4-oxo-4,7-dihydroisothiazolo[5,4-b]pyridine-5-carboxylate

Participants

Reaction Conditions

Reaction Steps

Diethyl 2-((3-methylisothiazol-5-ylamino)methylene)malonate (10 g, 35.17 mmol) was added to refluxing diphenyl ether (40 mL) and the reaction was held at reflux (259° C.) for 3.5 h. After the starting material had been consumed, the reaction was allowed to cool to room temperature. The product was precipitated as a dark brown solid by adding diethyl ether (100 mL) to the cooled reaction mixture. The solid was filtered, washed with ether and allowed to air dry. The product ethyl 3-methyl-4-oxo-4,7-dihydroisothiazolo[5,4-b]pyridine-5-carboxylate was obtained as a brown powder (5.5 g, 66% yield). LC/MS m/z 239.0 [M+H]+, retention time 0.91 min (RP-C18, 10-99% CH3CN/0.05% TFA over 3 min).

Provenance & Evidence