| 摘要 |
<p>Novel halogenated cephalosporin derivatives having the formula <IMAGE> where X is amino, azido or protected amino, R is carboxyl or protected carboxyl, and Hal is halogen, and salts thereof, are prepared by addition of a thiol or selenol to a starting material of the formula <IMAGE> where X1 is azido or protected amino; oxidising the adduct to give <IMAGE> where Y is Se or S; halogenating and eliminating HO-Y-R' to give the halogenated cephalosporin products. The free amino derivatives (X=NH2) and free carboxyl derivatives (R=COOH) are obtained by removal of the protecting groups.</p> |
