Heteroaryl radicals. Part 1. Synthesis of linear pyridine-fused ring systems by endo-selective 2-pyridyl radical cyclizationsThis paper has been dedicated to Professor U. R. Ghatak on the occasion of his 70th birthday.

Maiti, Sarbendu; Achari, Basudeb; Mukhopadhyay, Ranjan; Banerjee, A.

doi:10.1039/b204436f

Cited by 14 publications

(2 citation statements)

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“…The application of 2-pyridyl radicals in synthesis is uncommon and from the few reports that exist it appears that these radicals prefer to undergo endo cyclisation onto alkenes, which has been attributed to the "distorted geometry" of the 2-pyridyl radical and is caused by the overlap of the nitrogen lone pair with the radical centre (resonance stabilisation) as is observed for acyl radicals. [32][33][34] We have previously suggested that this distortion disfavours the homolytic substitution pathway and is, in part, responsible for the poor yields observed in our experiments. 22 This distortion is clearly evident in Fig.…”

Section: Methodsmentioning

confidence: 57%

Intramolecular homolytic substitution of sulfinates and sulfinamides – a computational study

et al. 2011

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Ab initio and density functional theory (DFT) calculations predict that intramolecular homolytic substitution by alkyl radicals at the sulfur atom in sulfinates proceeds through a smooth transition state in which the attacking and leaving radicals adopt a near collinear arrangement. When forming a five-membered ring and the leaving radical is methyl, G3(MP2)-RAD//ROBHandHLYP/6-311++G(d,p) calculations predict that this reaction proceeds with an activation energy (ΔE(1)(‡)) of 43.2 kJ mol(-1). ROBHandHLYP/6-311++G(d,p) calculations suggest that the formation of five-membered rings through intramolecular homolytic substitution by aryl radicals at the sulfur atom in sulfinates and sulfinamides, with expulsion of phenyl radicals, proceeds with the involvement of hypervalent intermediates. These intermediates further dissociate to the observed products, with overall energy barriers of 45-68 kJ mol(-1), depending on the system of interest. In each case, homolytic addition to the phenyl group competes with substitution, with calculated barriers of 51-78 kJ mol(-1). This computational study complements and provides insight into previous experimental observations.

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Section: Methodsmentioning

confidence: 57%

Intramolecular homolytic substitution of sulfinates and sulfinamides – a computational study

et al. 2011

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“…Intramolecular Bu 3 SnH mediated 2-pyridylradical cyclization of methylenecyclohexane or vinyl/ allylcyclohexanols for the terminal olefinic carbon center constitutes an efficient method of preparing pyridine-ringfused six-, seven-and eight-membered-ring annulated polycyclic compounds, which are not accessible by classical methodology (eq. 27) [76].…”

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confidence: 98%

Strategies in Synthetic Radical Organic Chemistry. Recent Advances on Cyclization and SRN1 Reactions

Rossi¹,

Peñéñory

2006

COS

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Intramolecular Homolytic Substitution of Sulfinates and Sulfinamides

Coulomb

Certal

Larraufie

et al. 2009

Chemistry A European J

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A general and efficient method for the synthesis of cyclic sulfinates and sulfinamides based on intramolecular homolytic substitution (S(H)i) at the sulfur atom by aryl or alkyl radicals is described. Both alkyl and benzofused compounds can be accessed directly from easily prepared acyclic precursors. Enantiomerically enriched sulfur-based heterocycles were formed through an S(H)i process with inversion of configuration at the sulfur atom. Cyclization of prochiral radicals proceeded with varying stereochemical outcomes, depending on the size of the incoming radical. 2-Pyridyl and 2-quinolyl radicals led to biaryl compounds, which result from attack onto the ortho position of the arylsulfinate rather than a thiophilic substitution.

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Heteroaryl radicals. Part 1. Synthesis of linear pyridine-fused ring systems by endo-selective 2-pyridyl radical cyclizationsThis paper has been dedicated to Professor U. R. Ghatak on the occasion of his 70th birthday.

Cited by 14 publications

References 23 publications

Intramolecular homolytic substitution of sulfinates and sulfinamides – a computational study

Intramolecular homolytic substitution of sulfinates and sulfinamides – a computational study

Strategies in Synthetic Radical Organic Chemistry. Recent Advances on Cyclization and SRN1 Reactions

Intramolecular Homolytic Substitution of Sulfinates and Sulfinamides

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