UN PROCEDIMIENTO PARA LA PREPARACION DE UN ACIDO 7 BETA- ACILAMIDO-3-HIDROXIMETILCEF ETERIFICADO-3-EM-4-CARBOXILICO.

摘要

1,241,656. 3-Etherified cephalosporin derivatives. GLAXO LABORATORIES Ltd. 6 Aug., 1968 [21 Aug., 1967], No. 38493/67. Headings C2A and C2C. [Also in Divisions A5-A6] Novel 7#-acylamino-3-etherified hydroxymethyl-ceph-3-em-4-carboxylic acids are prepared either (a) by N-acylating the corresponding 7#-amino-3-ether, which compounds are also novel, e.g. by reaction with an acid halide, anhydride or mixed anhydride, an active ester or azide, or an acid together with an esterifying agent; or (b) by reacting a 7#- acylamido - 3 - PCH 2 - ceph - 3 - em - 4 - carboxylic acid, wherein P is a group replaceable by an ether group, with an etherifying agent, optionally followed by N-deacylation and reacylation with a different acyl group, preferably by the method of Specification 1,241,655. P may be either a hydroxy or an acetoxy group. When P is hydroxy, etherification may be effected either directly, by reacting the compound with an orthoester such as MC(OR) 3 wherein M is hydrogen, alkyl or -OR and R is the required etherifying radical, or with a diazo compound, or an unsaturated compound activated by electron donating or attracting groups; or indirectly by first converting the 3-hydroxymethyl group to a 3-CH 2 X group where the corresponding acid HX has a pKa of not more than 4, and then reacting the 3- CH 2 X containing compound with an alcohol or phenol to convert X to the required ether group. The group X may be an ester group formed by esterifying the CH 2 OH group with, e.g. halo-, methoxy-, alkylthio-, or cyanoacetic acid, phenyl- or substituted phenylglyoxylic acid or glyoxylic acid itself, phenylpropiolic acid or formic acid; other examples of X are halogen, thio-ether groups, and isothiocyanate groups. When P is acetoxy, this group may be directly displaced by reaction with an alcohol or phenol in a polar medium to give the corresponding ether. In many of these procedures, the 4-carboxyl and 7#-amino group (if present), and any other carboxyl or amino substituent groups present, are protected by easily removable groups, e.g. urethane, trityl, arylmethylene, sulphenyl or enamine groups; alternatively the carboxyl group may be esterified and reaction conditions used wherein the NH 2 group remains protonated. D(-) -α- Formyloxy -α- phenylacetyl chloride is prepared by refluxing in benzene a mixture of D(-)-mandelic acid, p-toluenesulphonic acid and formic acid, to give D(-)-α-formyloxy-α- phenylacetic acid, which is isolated and then refluxed in benzene with thionyl chloride to give the required product.