反应详情

To a stirred solution of ethyl 4-(allyloxy)-3-vinylbenzoate (1.8 g, 7.7 mmol) in CH2Ci2 (40 mL) at rt is added benzylidene-bis(tricyclohexylphosphine)dichlororuthenium (127 mg, 0.15 mmol). The mixture is stirred at rt for 2.5 h. The reaction mixture is concentrated in vacuo to a dark residue. The crude product is purified by flash chromatography on SiO2. Elution with hexanes-EtOAc (95:5) gives 1.3 g (80%) of ethyl 2H-chromene-6-carboxylate as a clear oil: 1H NMR (400 MHz, CDCl3) δ 7.8, 7.7, 6.8, 6.4, 5.8, 4.9, 4.4, 1.4.

1. concentrationThe reaction mixture is concentrated in vacuo to a dark residue
2. customThe crude product is purified by flash chromatography on SiO2
3. washElution with hexanes-EtOAc (95:5)