Penicillin sulphoxides synthesis

Oxidation of phenyl hexyl sulphide with sodium metaperiodate gave also only a trace amount of the corresponding sulphoxide72. On the other hand, Hall and coworkers73 prepared benzylpenicillin and phenoxymethyl penicillin sulphoxides from the corresponding benzyl esters by oxidation with sodium metaperiodate in dioxane solution with a phosphate buffer. A general procedure for the synthesis of penicillin sulphoxides was reported later by Essery and coworkers74 which consists in the direct oxidation of penicillins or their salts with sodium metaperiodate in aqueous solution at pH 6.5-7.0. 1-Butadienyl phenyl sulphoxide 4475 and a-phosphoryl sulphoxides 4576 were also prepared by the same procedure. 

Parr method 995 Pauling s electronegativities 561 Penicillin sulphoxides epimerization of 750 synthesis of 246 Peptides 854, 864-866... 

A convenient high yield synthesis of 3-iodo-3-methylcephams (373) and 3-alkoxy-3-methylcephams is by reaction of the thiazoline azetidinone (372) with iodine or sulphenyi halides. Cooper first reported that (374), a degradation product of penicillin, gave a mixture of penicillin sulphoxide (376) and desacet-oxycephalosporin sulphoxide (377) when treated with /w-chloroperoxybenzoic acid in the presence of TFA, and this transformation was used in Kishi s biogenetic-type synthesis of penam and cephem derivatives- The results are not always... 

Sulphenyl Halides.—Sulphenyl chlorides are readily available by chlorinolysis of disulphides, and this remains the most commonly used method of synthesis. Chlorinolysis of penicillin esters gives the sulphenyl chloride, and a route to an azetidinone sulphenyl chloride has been devised in which the relatively unstable sulphenic acid produced by penicillin sulphoxide pyrolysis is treated with SOCh in CCl, to give [43 R =C1, R =CH(C02Me)CMe=CH2]. Sulphenyl iodides may be important intermediates in reactions at disulphide bridges in peptides and proteins, and a report of the preparation of a stable sulphenyl iodide is notable. The observation that methanesulphenyl chloride dimerizes (in SO2 in the presence of a Lewis acid) to give MeSSMeCl Cl MeS=SMeCl Cl may be useful in explaining the course of certain electrophilic reactions of sulphenyl chlorides, and should stimulate a search for new reactions of aliphatic compounds of this series. 

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