Cephem 10-oxide ring

Oxidative ring closure to thiadiazoles. Modified cephalosporins of type 3 have been prepared from 3-formyI-3-cephems 1 as shown in equation (I 3... 

Without additional reagents 3-Isothiazolone from cephem ly -oxide ring... 

Oxidation reactions on the sulfur atom of penicillins remain the most important reactivity of S-1 encountered in the literature. Penam sulfoxides and sulfones are indeed important compounds as they confer to the skeleton an ease of thiazolidine ring opening by weakening the C(5)-S(l) and S(l)-C(2) bonds (see Section 2.03.5.9) <2004CHE816>. In particular, the former constitute key intermediates in ring-expansion transformations from penams to cephems (see Section 2.03.5.9), while the latter have a special biological interest as /3-lactamase inhibitors (e.g., sulbactam, tazobactam see Sections 2.03.1, 2.03.5.2, and 2.03.12.4). Since CHEC-II(1996) covers all the aspects of these oxidation reactions on the S-1 atom of penicillins, this section focuses on the most relevant recent papers. As there is no particular change in the subject, only a few articles have been released since 1995. 

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