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Kyne SH Aitken HM Schiesser CH Lacôte E Malacria M Ollivier C Fensterbank L 《Organic & biomolecular chemistry》2011,9(9):3331-3337
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. 相似文献
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A variety of 1-allenyl-2-propargyl-substituted cyclopentanol derivatives were found to undergo facile intramolecular microwave-assisted [2+2] allenyne cycloaddition reactions to generate tricyclic 5-6-4 ring systems present in the sterpurenes. 相似文献