Cesium carbonate → Tert-butyl 4-(4-(4-(ethoxycarbonyl)oxazol-5-yl)phenyl)piperazine-1-carboxylate

Participants

Reaction Steps

A solution of tris(dibenzylideneacetone)dipalladium(0) (0.079 g, 0.09 mmol), 9,9-dimethyl-4,5-bis(diphenylphosphino)xanthene (0.100 g, 0.17 mmol), ethyl 5-(4-bromophenyl)oxazole-4-carboxylate (0.500 g, 1.69 mmol), tert-butyl 1-piperazinecarboxylate (0.409 g, 2.20 mmol) and cesium carbonate (0.786 g, 2.41 mmol) in dioxane (25 ml) and t-butanol (25 ml) was degassed, placed under a nitrogen atmosphere and heated under reflux overnight. The solvent was removed in vacuo and the residue partitioned between water and DCM. The organic phase was dried over MgSO4 and the solvent removed in vacuo. The residue was purified by silica gel column chromatography using 50% EtOAc in hexane as eluant to afford tert-butyl 4-(4-(4-(ethoxycarbonyl)oxazol-5-yl)phenyl)piperazine-1-carboxylate (0.340 g, 0.85 mmol, 50%) of a yellow solid. 1H NMR (CDCl3) δ 1.42 (3H, t), 1.49 (9H, s), 3.28 (4H, br. t), 3.59 (4H, br. t), 4.42 (2H, q), 6.95 (2H, d), 7.83 (1H, s), 8.05 (2H, d). LCMS (1) Rt: 2.37 min; m/z (ES+) 402.

Provenance & Evidence