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Reactions and determination of stereochemistry of 3-methylenecepham derivatives

✍ Scribed by Michihiko Ochiai; Osami Aki; Akira Morimoto; Taiiti Okada

Publisher
Elsevier Science
Year
1972
Tongue
French
Weight
198 KB
Volume
13
Category
Article
ISSN
0040-4039

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✦ Synopsis

In the previous communications, 1,2) we reported the facile syntheses of a novel class of cephalosporlns, 3-methylenecepham derivatives, by an electrochemical reduction or chromium(I1) salts reduction of cephalosporanic acids. This communication describes some aspects of chemical reactions of these compounds and also the establishment of the stereochemistry at position 4. Esterlficatlon of Ia by the conventional treatment with diazomethane gave the 3-methylenecepimn methyl ester (Ib), m.p. 145-147'C, IR (KBr)l 1765 cm-l (R-lactam), NMR (a, 100 MC, CDC13): 3.17 and 3.68 (two doublets, 2H, 2-C&), 5.10 (singlet, lH, 4-CH), 5.21 (broad doublet, 2H, C=ClX2), 5.39 (doublet, lH, 6-cg), 5.69 (doublet of doublet, lH, 7-CH).

Oxidation of Ib with g-chloro-

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