Cesium carbonate → tert-Butyl 1-(tert-butoxycarbonyl)-2-(5-tert-butyloxazol-4-yl)vinylcarbamate

Participants

Reaction Steps

To a solution of N-(tert-Butoxycarbonyl)-α-dimethylphosphonoglycine-tert-butyl ester (11.8 g, 34.68 mmol) and 5-tert-butyloxazole-4-carboxaldehyde (6.9 g, 45.08 mmol) in DMF (50 mL) was added Cs2CO3 (12.4 g, 38.15 mmol) under an argon atmosphere at room temperature. The reaction mixture was stirred for 14 h at room temperature. After removal of solvent in vacuo, the residue was dissolved in AcOEt, successively washed with 10% citric acid, 5% NaHCO3 and saturated NaCl for three times, dried over Na2SO4, and concentrated in vacuo. The residual oil was purified by a silica gel column chromatography to yield 6.0 g (47%) of title compound as a white solid: mp 170-172° C.; 1H NMR (300 MHz, CDCl3) δ 7.74 (s, 1H), 6.55 (s, 1H), 1.54 (s, 9H), 1.49 (s, 9H), 1.38 (s, 9H); HRMS (EI): m/z 366.2159 (M+) (calcd for C19H30N2O5: 366.2154).

Provenance & Evidence