Compounds represented by the following formula prepared from 6-aminopenicillanic acid are key intermediates in a stereo-specific synthesis of 1-oxadethiacephalosporins, highly active antibiotics: ##STR1## [wherein COA and COB each is carboxy or protected carboxy; COX is carboxy, protected carboxy, or a group of the formula --COCQ.dbd.N.sub.2 or --COCHQ--Z (in which Q is hydrogen, lower alkyl or aryl; and Z is hydrogen or a nucleophilic group); Hal is halogen; R is lower alkyl or aralkyl; and Y is hydrogen or acyl].
以下化合物的分子式是由6-
氨基
青霉酸制备而成,是1-氧代
硫代
头孢菌素的立体特异性合成的关键中间体,是高效的抗生素:##STR1## [其中COA和COB分别是羧基或受保护的羧基;COX是羧基,受保护的羧基,或具有公式--CO
CQ.dbd.N.sub.2或--COCHQ--Z的基团(其中Q是氢,低碳基或芳基;Z是氢或亲核基团);Hal是卤素;R是低碳基或芳基烷基;Y是氢或酰基]。