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

Participants

Reaction Steps

To a solution of tert-butyl 4-({[5-bromo-2-(methoxycarbonyl)thiophen-3-yl]carbamoyl}amino)piperidine-1-carboxylate (37.6 g; compound B54a) in dry MeOH (205 ml) under argon atmosphere is added sodium methoxide (6.16 g) at RT. The reaction mixture is refluxed for 3 h, allowed to cool to RT and then poured into a solution of citric acid (21.9 g) in ice cold water (961 ml). The precipitated solid is filtered off, washed with ice cold water and dried in vacuo. The residue is taken up in MeOH (205 ml) and the resulting suspension is refluxed for 1 h. After cooling to RT all solids are filtered off, washed with MeOH and dried in vacuo to afford the title compound as a solid.

Provenance & Evidence