Penicillin S-oxides

Winterfeldt has shown that the reaction of dimethyl sulfoxide with DMAD gives tetramethyl furantetracarboxylate (345), and it was suggested that this reaction may proceed through the intermediates 342, 343, and.344 (Scheme 52). The reaction of /-butylsulfenic acid with methyl propiolate, however, gives /3v -bis(/ra/is-carbomethoxy)divinyl sulfoxide (348) (Scheme 53). The penicillin S-oxide (349) is known to react with DMAD to give the adduct 352, and this reaction has been assumed to proceed through the sulfenic acid intermediate 350 (Scheme 54). ... 

An interesting reaction related to the ring expansions of penicillin S-oxides (208) was observed in the thermal rearrangement of 2,2,4A-tetramethyl-thiethan-3-one 1-oxide to the five-membered thiolane ring 209. Oxidation attempts of these thermally unstable thietanone oxides led via ring opening to the more stable heterocycle. The reaction mechanism (Scheme 11) was... 

Harrison, C.R. and Hodge, P., Determination of the configuration of some penicillin S-oxides by 13C nuclear magnetic resonance spectroscopy, J. Chem. Soc. Perkin Trans., I, 1772, 1976. 

Cephalosporin S-oxides and penicillin S-oxides (221) can be converted into isothiazol-3-ones (222) by the action of bases. These reactions proceed via an intermediate azetidinonesulfenic acid (223 Scheme 37) (77SST(4)339). Attempts to prepare /3-lactam compounds from isothiazoles have, as yet, been unsuccessful (81T2181). 

Penicillin-S-oxide liefern bci der Behandlung mit Trimethylphosphit unter Offnung beider Ringe und Recyclisierung N-substituierte 2-Alkoxy-4-(l-diphenylmethoxycarbonyl-2-me-thyl-2-propcnylaminocarbonyl)-l, 3-thiazole (80%)909 ... 

Azodiisobutyronitrile Penicillin S-oxide ring by radical rearrangement... 

Participation s. Neighboring group participation Pathway control -, reaction of oximes with nitrosyl chloride 26, 258s31 Pearson degradation 9,294 Penicillin S-oxide ring... 

Startg. penicillin S-oxide deriv. refluxed 2 hrs. in benzene under Ng with 100%-excess silylating agent such as trimethylsilylacetamide product. Y almost 100%. F. e. s. T. S. Chou, Tetrah. Let. 1974, 725. 

Methanesulfonic acid Cephalosporins from penicillin S-oxides O... 

Bond Cleavage.—The thermal or acid-catalysed rearrangement of penicillin (S-oxides to cephalosporins has been shown to proceed through a reactive sulphenic acid (80 y), which may be isolated in crystalline form in low yield. This intermediate slowly reverts on standing to the starting sulphoxide, while under acid... 

A variety of organic peroxy acids such as perbenzoic acid, MCPBA. monoperoxyphthalic acid, peracetic acid and trifiuoroperacetic acid are much stronger oxidants dian H2O2, and oxidize sulfides to sulfoxides under very mild conditions. Usually 1 equiv. of peroxy acid to sulfide is employed, otherwise overoxidation easily occurs to give sulfones. Among these, MCPBA has die advantage of being convenient to use and Ae oxidation is normally carried out at 0 C or lower temperatures, in di-chloromethane. The preparations of the base-sensitive sulfoxide (15), a new dienophile alkynyl sulfoxide (16), " and thiiraneradialene S-oxide (17) are typical examples. Selective oxidation of the sulfur atom of penicillins by polymer-supported peroxy acids in DMF or acetone is also known (equation 17). ... 

Using this method, 6-aminopenicillanic acid (6-APA) was successively subjected to benzoylation, esterification with benzhydrol, S-oxidation, and subsequent epimerization at the C-6 position, giving epi-penicillin 1 P-oxide ester (49). 

Acyclic sulphides handled during a continuing study of the reactions of penicillins and cephalosporins are the result of reaction of methyl fluorosulphonate, methyl chloroformate, and acetyl chloride with penicillin-derived thiazine S -oxides. 4-Methylthioazetidinones formed by treatment of penicillin esters with Mel and strong base suffer replacement of the MeS group by acetoxy on treatment with Pb(OAc)4. The MeS group turns up unexpectedly on the... 

Transformation of Penicillins Reactions of Penam S-Oxides with N-Chloro-N-sodio-carbamates. J. Chem. Soc., Perkin I 1977, 1943. 

Reactions of Sulphenic Acids.—In continuation of previous work, penicillin sulphenic acids have been trapped with vinyl ethers and keten acetals, " " with thiols, alkenes, and alkynes. A variety of products from thermolysis of N-benzyloxycarbonyl-L-(S-t-butyl)cysteinyl-L-valine methyl ester S-oxide must derive from an intermediate sulphenic acid, and isothiazolones and thiazinones formed from penicillin sulphoxides are also satisfactorily accounted for on the same basis. "... 

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