BICYCLIC ANALOGUES WITH MORE THAN TWO RING-HETEROATOMS

BICYCLIC ANALOGUES WITH MORE THAN TWO RING-HETEROATOMS 

Nuclear analogues of cephalosporins containing two sulphur atoms (e.g. (205) [142,143] and (206) [143,144]) belong to this group, but some of their chemistry and properties were summarized in Part 1. Highly-substituted l-oxa4-aza- 

An interesting new reaction of penicillins with chloramine T gave rise to the formation of an ylide (211) [147] containing a substituted 1-aza-2-thiaoctam ring. Thermolysis resulted in the further transformation product (212) [148]. 

In an attempted ring-enlargement reaction, surprisingly, anhydropenicillin G (16) was obtained instead of 3-cephems [149]. In this reaction participation of a 1-thia-2-azaoctam derivative (214) was proposed, but this compound was not 

The a- and /3-sulphoxides were obtained by this means, starting with the a-and /3-sulphoxides of the corresponding penams (215a,b). 

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