Cephem-3-C-carboxamide (5) and Imide (6). The nitrone 2 (0.548 g) was dissolved in 30 ml of distilled acetic anhydride, acetic acid (4 drops) was added, and the solution was heated at 80'for 10 min and then cooled in an ice bath. Evaporation to dryness followed by chromatography on silica gel using a toluene-ethyl acetate gradient gave 0.161 g (27%) of the faster moving imide 6 and 0.287 g (52%) of the amide 5. 5: needles from CHzClz- ...