Abstract: Trimethylsilyl or another easily hydrolyzed ester of 6-trimethylsilyloxycarbonylaminopenicillanic acid was prepared by bubbling dry carbon dioxide into an anhydrous solution of the corresponding 6-trimethylsilylaminopenicillanate and found to be a useful intermediate in the production of penicillins, e.g., amoxicillin and ampicillin, by its acylation in anhydrous media with the appropriate acid chloride or acid chloride hydrochloride.

Abstract: In the preferred embodiment of the present invention trimethylsilyl 7-trimethylsilyloxycarbonylaminodecephalosporanate was prepared by bubbling dry carbon dioxide into an anhydrous solution of trimethylsilyl 6-trimethylsilylaminodecephalosporanate and found to be a useful intermediate in the production of cefadroxil and cephalexin by its acylation in anhydrous media with the appropriate 2-phenylglycyl chloride hydrochloride. Other cephalosporins are produced by acylation of 7-trimethylsilyloxycarbonylaminoceph-3-em-4-carboxylic acids or esters having a variety of substituents at the 3-position.

Abstract: 7-Aminocephalosporanic acid (7-ACA) and 7-amino-3-methyl-3-cephem-4-carboxylic acid (7-ADCA) are valuable intermediates in the preparation of semi-synthetic cephalosporins. These compounds are commonly prepared by cleaving the amide bond of compounds having the formula ##SPC1##In which R.sup.6 is H or ##EQU1## R is the side chain of a known penicillin, especially phenoxymethyl or benzyl, and the amino and carboxyl functions are blocked; byA. halogenating the blocked compounds Ia or IIa to produce an imino-halide;B. forming an imino-ether from the imino-halide by treatment with an alcohol; andC. mixing said imino-ether with water or an alcohol to produce 7-aminocephalosporanic acid or 7-amino-3-methyl-3-cephem-4-carboxylic acid.The invention claimed is the use of dicyclohexylamine or diisopropylamine instead of a tertiary amine acid scavenger in step A.