摘要 |
Novel azetidine derivatives of the formula <IMAGE> I wherein R1 is an acylamido group, R2 is selected from the group consisting of <IMAGE> <IMAGE> <IMAGE> <IMAGE> IIA IIB IIC IID wherein R4, R5 and R6 are individually selected from the group consisting of hydrogen, lower alkyl and lower alkenyl, n is 2 or 3 and - in the case when formula IIB is a phenyl - this group may carry one to four substituents selected from the group consisting of halogen, lower alkyl, lower alkenyl and phenyl, and R3 is lower alkyl optionally substituted with 1 or 2 phenyls which phenyl groups may be substituted with nitro and the dotted lines of formula IIB indicate the optional presence of double bonds and a process for their preparation and process for the preparation of cephalosporanic acid derivatives using the azetidines of formula I as intermediates. |