Issue 9, 2011

Intramolecular homolytic substitution of sulfinates and sulfinamides – a computational study

Abstract

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 (ΔE1) 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.

Graphical abstract: Intramolecular homolytic substitution of sulfinates and sulfinamides – a computational study

Supplementary files

Article information

Article type
Paper
Submitted
08 Jan 2011
Accepted
21 Feb 2011
First published
29 Mar 2011

Org. Biomol. Chem., 2011,9, 3331-3337

Intramolecular homolytic substitution of sulfinates and sulfinamides – a computational study

S. H. Kyne, H. M. Aitken, C. H. Schiesser, E. Lacôte, M. Malacria, C. Ollivier and L. Fensterbank, Org. Biomol. Chem., 2011, 9, 3331 DOI: 10.1039/C1OB05043E

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