- IMPROVED PROCESS FOR THE PREPARATION OF CEPHALOSPORIN ANTIBIOTICS
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Abstract The present invention more particularly relates to a process for the preparation of cephalosporin antibiotics of the Formula (I) wherein R1 represents hydrogen, trityl, alkyl like CH3, CRaRbCOORc where Ra and Rb independently represent hydrogen or methyl and Rc represents hydrogen or (C1-C6) alkyl; R2 is carboxylate ion or COORd, where Rd represents hydrogen, ester or a counter ion which forms a salt; R3 represents hydrogen, CH3, CH2OCH3, CH2OCOCH3, CH=CH2, Formula (II).
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- NOVEL INTERMEDIATES FOR SYNTHESIS OF CEPHALOSPORINS AND PROCESS FOR PREPARATION OF SUCH INTERMEDIATES
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A novel 4-halo-2-oxyimino-3-oxo butyric acid-N, N-dimethyl formiminium chloride chlorosulfate of formula (I) useful in the preparation of cephalosporin antibiotics, wherein X is chlorine or bromine; R is hydrogen, C1-4 alkyl group, an easily removable hydroxyl protective group, -CH2COOR5, or -C(CH3)2COOR5, wherein R5 is hydrogen or an easily hydrolysable ester group. The compound of formula (I) is prepared by reacting 4-halo-2-oxyimino-3-oxobutyric acid of formula (IV1), wherein X, R and R5 are as defined above, with N, N-dimethylformiminium chloride chlorosulphate of formula (VII), in an organic solvent at a temperature ranging from -30 °C to -15 °C. The cephalosporins that may be prepared from the intermediate include cefdinir, cefditoren pivoxil, cefepime, cefetamet pivoxil, cefixime, cefmenoxime, cefodizime, cefoselis, cefotaxime, cefpirome, cefpodoxime proxetil, cefquinome, ceftazidime, cefteram pivoxil, ceftiofur, ceftizoxime, ceftriaxone and cefuzonam.
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