Citric Acid → tert-butyl 4-(2,4-dioxo-6-phenyl-1,4-dihydrothieno[3,2-d]pyrimidin-3(2H)-yl)piperidine-1-carboxylate

Participants

Reaction Steps

To a solution of tert-butyl 4-({[2-(methoxycarbonyl)-5-phenyl-3-thienyl]carbamoyl}amino)piperidine-1-carboxylate (2.00 g; compound B51) in MeOH (20 ml) is added sodium methoxide (300 mg) in three portions at RT. The reaction mixture is refluxed for 3 d and then allowed to come to RT. Ice cold water (30 ml) is added and the pH is adjusted to 4 by addition of citric acid. The resulting suspension is stirred for 2 h at RT; then the precipitate is filtered off, washed with water and dried in vacuo at 50° C. The crude title compound is taken up in MeOH (25 ml) and refluxed for 3 h. The hot suspension is filtered, and the filter cake is washed with hot MeOH three times and dried in vacuo at 45° C. to afford the title compound as a solid.

Provenance & Evidence