| 摘要 |
2-chlorosulfinyl-azetidin-4-ones of the formula …<CHEM>… wherein R is the residue of a carboxylic acid and R1 is a carboxylic acid protecting group, are prepared by reacting a penicillin sulfoxide ester of the formula …<CHEM>… wherein R and R1 are as defined above, with an N-chlorohalogenating agent, e.g. N-chlorophthalimide, in an inert organic solvent, e.g. toluene, under essentially anhydrous conditions in the presence of a cross-linked polyvinylpyridine polymer, e.g. poly-(4-vinylpyridinel), said polymer containing between about 1 percent and about 10 percent cross-linking with e.g. divinylbenzene. …<??>The 2-chlorosulfinylazetidin-4-ones are used as intermediates for the preparation of 3-exomethylenecepham-4-carboxylic acid ester sulfoxides. |
