Improved method for preparation of cefixime trihydrate

摘要

The invention provides an improved method for the preparation of cefixime trihydrate of formula I: , Formula I The 7(amino-substituted) cephalosporanic acid undergoes hydrolysis with alkaline carbonate followed by acylation at the 7-amino group with organic acid chloride and esterification at the 4-carboxy group to yield the protected 4-hydroxymethylcefeme, which after bromination with PBr3 and Wittig reaction with triphenylphosphine/aq. formaldehyde yields the protected 3-vinyl cefeme. The 7- phenylacetyl side chain is then cloven using a complex of triphenylphosphide/chlorine/pyridine/IBA to yield the 7- amino compound which, after binding to 4-chlor-2- methoxycarbonylmethoxy-imino-3-oxobutyric acid and ring formation with thiourea, yields the protected cefixime. Removal of the protecting groups yields the above- entitled compound.