Distinct fragmentation patterns of the radical anions derived from 1-halo-2- and -4-(phenylmethylthio)benzenes

Postigo, Al; Rossi, Roberto A.

doi:10.1039/a908522j

Cited by 6 publications

(4 citation statements)

References 26 publications

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“…Taking into account that there are precedents about ring opening of cyclic radical anions to give benzyl radicals and an anionic center, we propose that the formation of the rearranged product 20 is mediated by the conjugate radical anion 23 •− , which is formed by intramolecular cyclization at the nucleophilic N of intermediate 21 •− (eq ). The formation of 20 is inhibited by the presence of p -DNB and m -DNB (Table , entries 26 and 27).…”

Section: Resultsmentioning

confidence: 99%

Electron-Transfer-Mediated Synthesis of Phenanthridines by Intramolecular Arylation of Anions from N-(ortho-Halobenzyl)arylamines: Regiochemical and Mechanistic Analysis

et al. 2010

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The synthesis of a series of substituted phenanthridines by photostimulated C-C cyclization of anions from N-(ortho-halobenzyl)arylamines has been found to proceed in very good to excellent yields (79-95%) in liquid ammonia and in DMSO. The N-(ortho-halobenzyl)arylamines are obtained in good to very good isolated yields (44-85%) by nucleophilic substitution of ortho-halobenzylchlorides with different arylamines. The reaction of the anions of a diverse set of N-(ortho-halobenzyl)arylamines was studied, and the methodology was extended to the synthesis of trispheridine, a natural product, in very good yield. In order to explain the regiochemical outcome of these reactions, a theoretical analysis was performed with DFT methods and the B3LYP functional.

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Section: Resultsmentioning

confidence: 99%

Electron-Transfer-Mediated Synthesis of Phenanthridines by Intramolecular Arylation of Anions from N-(ortho-Halobenzyl)arylamines: Regiochemical and Mechanistic Analysis

et al. 2010

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“…15 In another o-substituted benzene system (in the absence of benzenethiolate ions), substituted phenyl radicals cyclize onto the o-position of adjacent S-benzyl groups. 16 A probable mechanism for the formation of 11, is shown in Scheme 3. The intermediate α-naphthyl radical is presumably more hindered by the peri-substituent than the corresponding phenyl radicals in o-substituted phenyl systems and this, together with the additional effect of changed geometry involved in the 1,8-arrangement in naphthalene systems, leads to exclusive formation of the cyclized product 11, rather than the disubstituted product normally expected from a double S RN 1 process.…”

Section: Methodsmentioning

confidence: 99%

“…The reaction of 1 with the potassium salts 5b and 5c gave no detectable amounts of the dimer 13 and yielded only 12 in DMSO and its deutero derivative 12-d 1 in DMSO-d 6 (entries [13][14][15][16].…”

Section: Figurementioning

confidence: 99%

The SRN1 reactions of 1,8-diiodonaphthalene

Norris¹,

McMahon²

2003

Arkivoc

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The reactions of 1,8-diiodonaphthalene with the enolate ions from pinacolone and acetone, and with p-toluenethiolate, mesitylenethiolate, and diethylphosphite ions in DMSO or liquid ammonia have been studied. In these S RN 1 (or related radical) processes, disubstitution, without isolation of the monosubstituted monoiodo compound takes place with the enolate ions to give ultimately (after a subsequent aldol condensation) substituted dihydrophenalenes. With ptoluenethiolate ion a novel thiaxanthene system results. With mesitylenthiolate ion and diethylphosphite ions, monosubstitution with monoreduction occurs. Deuterium labeling experiments show that the major source of hydrogen (deuterium) necessary for the reduction process arises from DMSO by a radical abstraction reaction.

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“…Postigo and Rossi observed that the fragmentation patterns of the radical anions of halo(phenylmethylthio)benzene varies with the position of the substituents on the benzene ring. 50 For 1-bromo-2-(phenylmethylthio)benzene (4.11, Scheme 4.14) and 1-iodo-4-(phenylmethylthio)benzene the products observed upon irradiation in the presence of pinacolone enolate ion were derived exclusively from C-S bond fragmentation of the phenylmethylthiyl moiety. However, 1-iodo-2-(phenylmethylthio)benzene (4.12, Scheme 4.14) provided products derived from C-I bond scission under identical photolysis conditions.…”

Section: Scheme 318mentioning

confidence: 99%