Abstract
On sequential treatment of benzylpenicillanates (1) or their sulfoxides (7) with phosphorus pentachloride, methanol, and sodium bicarbonate or dimethylaniline, 6-(dimethylphosphoramido) penicillins (5) or their sulfoxides (8) were obtained. 6-(Dimethylphosphoramido) penicillin sulfoxides (8) were rearranged thermally to their corresponding desacetoxycephalosporins (10). The dimethylphosphoryl group of 7-(dimethylphosphoramido) desacetoxycephalosporins (10) was removed by either a 85% phosphoric acid or polyphosphoric acid, which caused the degradation of β-lactam ring in 6-(dimethylphosphoramido) penicillins (5) and their sulfoxides (8). The dimethylphosphoryl group of penicillins and desacetoxycephalosporins was also removed by phosgene and pyridine to give 6-isocyanatopenicillins (16) and 7-isocyanatodesacetoxycephalosporins (15), respectively.
