| 摘要 |
A process for the preparation of compounds of formula I <CHEM> wherein R1 represents hydrogen or a hydroxy-proctecting group, R2 represents hydrogen, a cation, the pivaloyloxymethyl group or a carboxy-protecting group and R3 represents hydrogen, the acetoxy group, the carbamoyloxy group, a group S-Y whereby Y represents an unsubstituted or substituted heterocycle, or an optionally substituted pyridinium of formula <CHEM> whereby R4 and R5 are the same or different and each represent hydrogen, halogen, alkyl, hydroxy, carboxamido, alkoxycarbonyl amino, monoalkylamino or di-alkylamino or together represent an optionally substituted 5- or 6-membered carbocyclic ring, characterised by reacting a compound of formula IV <CHEM> wherein R1 represents a hydroxy protecting group and <CHEM> represents a 5- or 6-membered heterocycle which may contain in addition to the nitrogen atom one or two further heteroatoms and which may be substituted or anellated with an optionally sustituted benzene ring with a compound of formula III and if desired deprotecting the obtained end product and optionally converting an obtained product into a salt or vice-versa. |
