| 摘要 |
<p>1,263,343. Cephem-4-carboxylic acid esters. ELI LILLY & CO. 5 Aug., 1969 [12 Sept., 1968], No. 39210/69. Heading C2A. #<SP>2</SP>-Cephem-4-carboxylic acid esters having the formula are prepared by (a) converting a #<SP>3</SP>-cephem-4- carboxylic acid having the formula to the corresponding acid chloride; and (b) treating the acid chloride with 1-2 moles of a tertiary amine base having a pKa within the range of 7-11 and at least 1 mole of an esterforming aliphatic alcohol (as defined) having the formula R<SP>1</SP>OH at a temperature within the range of -100‹ to +50‹ C.; wherein X is hydrogen or acetoxy, R is an amino protecting group, and R<SP>1</SP> is the residue of the ester-forming alcohol. The compounds having the following formulae are stated to be novel and are claimed per se:</p> |
