反应详情

温度

80 °C

A solution of 1-dimethylamino-1-methoxyethylene (1.62 g) in dimethylformamide (3 cc) is added, in the course of 45 minutes, to a solution of 2-benzhydryloxycarbonyl-3-methyl-7-phenoxyacetamido-8-oxo-5-thia-1-azabicyclo[4.2.0]oct-2-ene (2.06 g) in dimethylformamide (15 cc) at 80° C. The mixture is then stirred for 10 minutes at 80° C. This yields a solution of 2-benzhydryloxycarbonyl-7-phenoxyacetamido-3-(2-dimethylaminoprop-1-en-1-yl)-8-oxo-5-thia-1-azabicyclo[4.2.0]oct-2-ene, which is poured into a stirred mixture of ethyl acetate (100 cc), distilled water (50 cc) and 1N citric acid (50 cc) at 0° C. The organic phase is separated off by decantation, washed with distilled water (2×100 cc), dried over sodium sulphate and concentrated to dryness under reduced pressure (20 mm Hg; 2.7 kPa) at 30° C. The residue is chromatographed on a column of Merck silica gel (0.06-0.2) (20 g) (diameter of the column: 2 cm; height: 16 cm). Elution is carried out with a 28/72 (by volume) ethyl acetate/cyclohexane mixture (600 cc), 30 cc fractions being collected. Fractions 7 to 16 are concentrated to dryness under reduced pressure (20 mm Hg; 2.7 kPa) at 20° C. This yields 3-acetonyl-2-benzhydryloxycarbonyl-7-phenoxyacetamido-8-oxo-5-thia-1-azabicyclo[4.2.0]oct-2-ene (0.53 g) in the form of a hard yellow foam.