title: 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 (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.
authors: School of Chemistry, Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Victoria, 3010, Australia. sara.kyne@strath.ac.uk
authors: Sara H
authors: SH
authors: Kyne
authors: Heather M
authors: HM
authors: Aitken
authors: Carl H
authors: CH
authors: Schiesser
authors: Emmanuel
authors: E
authors: Lacôte
authors: Max
authors: M
authors: Malacria
authors: Cyril
authors: C
authors: Ollivier
authors: Louis
authors: L
authors: Fensterbank
mesh_terms: D000577:Amides / Q000737:chemistry*; D003201:Computers; D008958:Models, Molecular; D015394:Molecular Structure; D013451:Sulfonic Acids / Q000737:chemistry*; D013455:Sulfur / Q000737:chemistry*
chemical_list: D000577:Amides; D013451:Sulfonic Acids; D013455:Sulfur