| 摘要 |
Penicillin sulfoxide esters having the sulfoxide group in the alpha -configuration are reacted with an N-chloro halogenating agent at a temperature between about 70 DEG C. and about 120 DEG C. in the presence of an alkylene oxide and preferably also calcium oxide to produce 2-chlorosulfinyl-azetidin-4-one intermediates. The chlorosulfinyl intermediates are then treated with a Friedel-Crafts catalyst, for example, stannic chloride to provide a 3-exomethylenecepham beta -sulfoxide. The latter compounds are useful in the preparation of 3-alkoxy and 3-halo substituted cephalosporin antibiotic compounds. |
