| 摘要 |
<p>Preparation of 1-ethoxycarbonyloxyethyl 6-(D-C-)-alpha-amino- alpha-phenyl-acetamido) -penicillanate of formula (I) by:- (a) reaction of ampicillin (V), pref. as an alkaline salt, with a reactive deriv. of acetoacetic acid to form the corresponding enamine (II); (b) reaction of (II) with alpha-bromo-diethylcarbonate Br-C(CH3)H-OCOOC2H5 (III) to form the 1-(ethoxycarbonyloxy)ethyl ester (IV) and (c) acid hydrolysis to yield (I). In formulae R1 is 1-4C alkyl, opt. substd. aryl or aralkyl; R2 is H, 1-4C alkyl, opt. substd. aryl or aralkyl; R3 is 1-4C alkyl, amino, aryloxy, 1-4C alkoxy, opt. substd. aryl or aralkyl and X is an alkali metal, an alkaline-earth metal or an organic base. (I) or bacampicillis is an antibiotic, which is well absorbed when administered orally and gives higher blood levels than does ampicillin. The present preparation gives excellent yields of high purity product. (III) is a useful reagent for preparing ethoxycarbonyloxy-ethyl esters of 6-APA, penicillins and cephalosporins and is pref. used in conjunction with a quaternary ammonium salt as catalyst e.g. tetra-n-butylammonium bromide.</p> |
