反应详情

(5R)-3-Vinyl-7-oxo-4-oxa-1-azabicyclo[3.2.0]hept-2-ene (345 mg., 2.5 mmole) was prepared from clavulanic acid (3.0 mmole) as described in Example 1. This diene was dissolved in benzyl acrylate (7 ml) and the resulting solution was heated at 80° (bath temperature) for 1.5 hours. The bulk of the benzyl acrylate was then removed by distillation at 100° (bath temperature)/0.5 mm Hg pressure; and the resulting residue was chromatography on silica gel (25 g) using 1:9→1:4 ethyl acetate/petroleum ether (b,p. 60°-80°) to give, in order of elution, the following compounds: (5R)-11-benzyloxycarbonyl-3-oxo-6-oxa-2-azatricyclo[5.4.0.02,5 ]-undec-7,8-ene as colourless prisms (20 mg), isomer I of the title compound as a colourless gum (80 mg), and isomer II of the title compounds as a colourless gum (55 mg).

1. temperaturethe resulting solution was heated at 80° (bath temperature) for 1.5 hours
2. customThe bulk of the benzyl acrylate was then removed by distillation at 100° (bath temperature)/0.5 mm Hg pressure
3. custom1:9→1:4 ethyl acetate/petroleum ether (b,p. 60°-80°)
4. customto give, in order of elution