| 摘要 |
<p>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.degree.C. and about 120.degree.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.-sul-foxide. The latter compounds are useful in the preparation of 3-alkoxy and 3-halo substituted cephalosporin antibiotic compounds.</p> |
