Sulphenes cyclization

Sulphonyl phosphates, reactions of 638 Sulphonyl radicals 215 cyclization of 1099 ESR spectra of 1090-1093 formation of 1094-1098 structure of 1090-1094 thermodynamic data for 1094 Sulphonyl sulphenes 196 Sulphonyl sulphoxides alkylation of 311 synthesis of 262... 

Aminopenicillanic acid (8) was converted to 6(5)-bromopenicillanic acid by trapping of the diazo-intermediate with hydrogen bromide. Esterification of the dicyclohexylamine salt (93) with p-methoxybenzyl bromide, followed by oxidation, afforded the sulphoxide (94) in 60% yield from 6-APA. Elaboration of this sulphoxide to the disulphide (96) was effected by the procedure established by Kamiya et al. [98] the sulphenic acid (95), formed by heating the sulphoxide to reflux in toluene, was intercepted by reaction with 2-mercaptobenzothiazole to yield the disulphide (96). The latter was transformed by base-catalysed double bond isomerization to the conjugated ester disulphide (97) [95% yield from (94)]. Reductive formylation of disulphide (97) then provided the formylthio-derivative (98). Cyclization of the oxalimide (99), obtained by ozonolysis of... 

The thieten 1,1-dioxide (48) has been prepared by cycloaddition of an enamine and sulphene at 0°C. Mild thermolysis causes a ready retrocyclo-addition to occur. Additional stable 3-sultines have been isolated, by the reaction of the anion of a sulphoxide with a ketone and cyclization of the resulting j3-hydroxy-sulphoxide with sulphuryl chloride. Treatment of 2-methylthietan (49) with alumina at 150-350 °C results in the formation of tetrahydrothiophen and but-3-enethiol. ... 

The 2-methylenethiepin 1-oxide (164) has been prepared by the thermolysis of (162). A 3-elimination produces the sulphenic acid (163), which cyclizes to give (164). ... 

Apart from one citation, all the papers collected here to illustrate the reactions of vinyl sulphoxides deal with addition reactions. " As would be expected from the nature of the sulphoxide functional group, there are several novel features in these addition reactions compared with those of other vinyl compounds. Pyrolysis of alkyl styryl sulphoxides gives benzothiophens. The proposed mechanism, which involves formation and homolysis of a sulphenic acid followed by cyclization, (54) (55), is supported by the formation of benzo-... 

A similar penicillin sulphoxide-cephalosporin transformation, initiated with acetyl chloride-pyridine, has also been described. The disulphide (93 b) and sulphenanilide (94 b) have been prepared from the sulphenic acid (80). These sulphenyl derivatives readily cyclize to penicillins (95 b) and cephems (96 b). 

The first general method of transforming a penicillin into a cephalosporin, the acid-catalysed rearrangement of penicillin sulphoxides, continues to receive attention. That this rearrangement proceeds via a sulphenic acid derivative has been further confirmed by isolation of the crystalline sulphenic acid (74 f, y) from the thermal rearrangement of the penicillin sulphoxide (27 f, y). This intermediate slowly reverts to the penicillin at 38 0, and, on treatment with methanesulphonic acid in dimethylacetamide, cyclizes to cephalosporin (75 f, y). Trapping of (74) by oxidation to the sulphinyl chloride (76 f, y) has been reported cyclization to a cephalosporin sulphoxide was accomplished under base catalysis/ Treatment of penicillin sulphoxides with azo-compounds also effects rearrangement to... 

Derivatives of sulphenic acids have been utilized in cephalo-sporin-penicillin interconversions. The sulphenyl chloride (88 f, y), obtained by chlorinolysis of penicillin, cyclized to the penicillin (89 f, y) and... 

The unique substance (168) should be mentioned because its structure should reflect some of the characteristics of a sulphine (benzoylimido-group in place of oxygen) and some of the characteristics of a N-sulphinylamine (fluorenylidene in place of oxygen). It was obtained by allowing N-chloro-sulphenylbenzamide to react with diazofluorene and then dehydro-halogenating the reaction product with triethylamine. It spontaneously cyclized to (169) at -30 °C but would react with vinylamines in a manner reminiscent of sulphenes, N-sulphonylamines, and N-sulphinylamines. A similar structure (124) was obtained from the reaction of chloramine-T with benzotrithione. 

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