Abstract: The present invention relates to a new, simple, and easy process for preparing cephalosporin antibiotics of the following formula (I), such as ceftazidime and cefixime. The process comprises acylating a 7-amino cephalosporanic acid derivative of the following formula (III) with a crystalline aminothiazole compound of the following formula (II): wherein R1 and R2 are the same or different and independently represent H, a C1-4 alkyl or C3-5 cycloalkyl group, R4 represents acetoxymethyl, methylpyridine, or vinyl, X represents chlorine or bromine, and the acid in the acid addition salt represents an inorganic acid, such as hydrochloric acid, or an organic acid, such as formic acid or acetic acid.

Abstract: The present invention relates to a new, simple, and easy process for preparing cephalosporin antibiotics of the following sub-formulas (I), such as cefixime.

Abstract: The present invention relates to a new crystalline aminothiazole derivative represented by the following formula (I) which is very useful for the preparation of cephalosporin antibiotics, including ceftazidime and cefixime, etc: wherein R1 and R2 are the same or different and independently represent H, an alkyl group of 1 to 4 carbon atoms, or a cycloalkyl group of 3 to 5 carbon atoms, X represents chlorine or bromine, and the acid in the acid addition salt represents an inorganic acid, such as hydrochloric acid, hydrobromic acid, sulfuric acid, or perchloric acid, or an organic acid, such as formic acid, acetic acid, trifluoroacetic acid, propionic acid, methanesulfonic acid, or benzenesulfonic acid.