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Communication | Special issue | Vol 7, No. 2, 1977, pp.839-849
Published online, 1st January, 1970
DOI: 10.3987/S-1977-02-0839
■ Synthetic Studies on β-Lactam Antibiotics. Part 5. A Synthesis of 7β-Acylamino-3-methyl-1-oxadethia-3-cephem-4-carboxylic Acids

Masayuki Narisada,* Hiroshi Onoue, and Wataru Nagata

*Shionogi Research Laboratories, Shionogi & Co. Ltd., Fukushima-ku, Osaka 553-0002, Japan

Abstract

Chloroazetidinone 10, prepared from 6-APA, was etherified with propargyl alcohol and zinc chloride to a 2:1 mixture of cis- and trans-ethers 18. The separated cis-ether 18 was converted into a keto ylide 21d, which was cyclized by intramolecular Wittig reaction to 3-methyl 1-oxacephalosporin 22. From this compound, four optically active 3-methyl oxacephalosporins 25a-d were prepared. Interestingly all of them except 25d, 1-oxacephalexin, exhibited antibacterial activity as four to eight times high as that of the corresponding cephalo- sporins.