Methylthio radical

ANI +. Structure identification was based on ion-molecule reactions with dimethyl disulfide the attachment of a methylthio radical, which usually characterized distonic... 

Arenesulphinylation 264 Arenesulphinylethanes, synthesis of 267 2-Arenesulphonyl-3-aryloxaziridines, as oxidizing agents 254 Arenesulphonyl azides, reactions of 641 At-Arenesulphonyliminopyridinium betaines, mass spectra of 160-162 Arenesulphonyl radicals 215, 1091 Aryldiazonium salts, reactions of 280, 281 Aryl(methylsulphinyl)(methylthio)alkenes, synthesis of 614... 

The radical formed on reduction of the methylthio group can be used to effect intramolecular cyclization of an unsaturated ring. 

Griffin and co-workers (30) measured the high-field EPR spectrum of o-(methylthio)-p-cresyl as a model for the tyrosyl Y272, which is covalently cross-linked to a cysteinyl residue C228 in GO. The radical spin density is localized on... 

A careful analysis based on these experimental results excluded a chain-propagation process [33a]. On account of the 3-position of the methylthio or methoxy substituent in the thiophene or pyrrole rings, three isomeric dimers may be formed. The main reaction path can be deduced from the mesomeric forms of the radical cations (2)". The two most important mesomeric structures are those with the unpaired electron in... 

In the photochemical one-electron oxidation of aromatic sulfides, dimer radical cations were formed in rapid equilibrium with monomeric radical cation (59). The complex formation of a- and tt-types has been shown to be sensitive to the steric and electronic influence of substituent. For the case of jo-(methylthio)anisole the formation of TT-type dimer was shown to be reduced due to steric hindrance of two methyl groups. No formation of dimer radical cation was observed for jo-(methoxy)thioanisole and diphenyl disulfide where the corresponding monomer radical cations are stabilized by the delocalization of positive charge on the sulfur atom. Density-functional calculations supported the experimental results. The intramolecular formation of similar radical... 

The cation-radicals depicted in Scheme 3.28 form on oxidation of e t(( -2-(2-hydroxy-2-methyl-ethyl)-enr/o-6-(methylthio)-bicyclo[2.2.1]heptane and e t(( -2-(carboxyl)-enr((9-6-(methylthio)-bicyclo[2.2.1]heptane, respectively. Asmus (1990) underlined that only the sulfur atom responds to the one-electron oxidation. This is understandable since sulfur is less electronegative than oxygen. Meanwhile, the onium state is more stable than the sulfonium one. 

Scheme 3.30 depicts an intriguing case, when one-electron oxidation of the conformationally constrained exo-2-(carboxy)-en(i(9-2-(ammo)-en(i(9-6-(methylthio)-bicyclo[2.2.1]heptane gives rise to a cation-radical in which an amino- and not a carboxylate group participates in the three-electron bond with sulfur (Glass 1995). 

Aprotic diazotization of 86 (R = Me or Ph) produced 55% of thianthrene and lesser amounts of 1-phenylthio- (or methylthio) dibenzothiophen (Scheme 14) together with deaminated products. Comparable yields of 2-methyl-, 2-methoxy-, 2,7-dichloro- and 2,8-dichlorothianthrenes were obtained using this synthetic route. It is suggested that ring closure involves an intramolecular homolytic substitution at sulfur with loss of the 5-substituent as a radical [74JCS(P1)1272]. 

There are virtually no reports of homolytic reactions on the triazolo-pyridines. Unsuccessful attempts have been made to treat triazolopyridine (1) with methyl radicals,25 and a free radical mechanism is suggested as a possibility in the replacement of the methylthio group by chlorine (Section IV,C).208... 

Triazine and some of its 3-methoxy, 3-methylthio or 3-amino derivatives (103) with the 5-position unsubstituted react with potassium cyanide to afford two products, the i-triazinyls (105) and the l,2,4-triazine-5-carboxamides (104). These are proposed to be formed via a cyanide adduct (73JHC343, 74JHC43). The bi-l,2,4-triazinyls (105) were also isolated when the triazines (103) were treated with sodium methoxide or potassium in liquid ammonia. It is suggested that the methoxide-catalyzed dimerization proceeds via an anionic intermediate (106), while the reaction with potassium in liquid ammonia occurs via a free radical process. 

The synthesis of 3-benzylcyclobutanone (3) is an illustration of an overall intramolecular alkylation of an acyl anion equivalent (Section 5.9). The a,a>-dihalide is 2-benzyl-l,3-dibromopropane, and the acyl anion equivalent is methyl methylthiomethyl sulphoxide2 the product is 1-methylsulphinyl-l-methylthio-3-benzylcyclobutane which is obtained as a mixture of cis/trans isomers [(9) and (10)] (Expt 7.3). Aqueous acid hydrolysis in ethereal solution unmasks the carbonyl group. The possible mechanism of the reaction is via a Stevens-type rearrangement of the intermediate sulphur ylide, which may proceed in a pericylic, radical or ion pair fashion. 

The S.. N bond formation can serve as a driving force of the conformational transition. Thus, the 2-amino-4-(methylthio)butanoic acid (methionine) cation radical exists in... 

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