Carbon tetrabromide → tert-butyl 4-{1-[(5-ethyl-2H-tetrazol-2-yl)methyl]-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 5-ethyl-2-{[(tripropan-2-ylsilyl)oxy]methyl}-2H-tetrazole (1.53 g; compound D30) in DCM is added n-Bu4NF (5.34 ml of 1M solution in THF) and stirred for 30 min at RT. After completion of the reaction (TLC monitoring, eluent system: EtOAc/c-Hexan, 1/6, (v/v)) CBr4 (2.13 g) and PPh3 (1.68 g) are added and the reaction mixture is stirred for 30 min at RT. The reaction mixture is added to a mixture of tert-butyl 4-(2,4-dioxo-6-phenyl-1,4-dihydrothieno[3,2-d]pyrimidin-3(2H)-yl)piperidine-1-carboxylate (913 mg; compound B50) and potassium carbonate (1.33 g) in DMF and the combined reaction mixture is stirred for 12 h at 80° C. All volatiles are evaporated under reduced pressure and the resulting residue is purified by flash chromatography (silica gel, eluent EtOAc/cyclohexane, 1/6, (v/v)) to give the title compound as a solid.

Provenance & Evidence