- The determination of sulfoxide configuration in five-membered rings using NMR spectroscopy and DFT calculations
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Cyclic five-membered ring sulfoxides and sulfones were prepared by a stepwise in situ oxidation of the corresponding sulfides with meta-chloroperbenzoic acid in an NMR tube. The oxidation was followed by NMR and both 1H and 13C NMR data were collected. The geometries of all of the compounds were optimized using the DFT B3LYP/6-31G method and the 13C and 1H chemical shifts were calculated for geometry-optimized structures with the DFT B3LYP/6-31++G method. The calculated 13C chemical shifts induced by oxidation (Δδ values) were in very good agreement with the experimental data and could be used to determine the oxidation state of the sulfur atom (-S-, -SO-, -SO2-). The characteristic differences of the induced oxidation chemical shifts of the carbon atoms in the α-position and β-position to sulfur were successfully used to distinguish between the diastereoisomeric sulfoxides and allowed configuration determination.
- Dracinsky,Pohl,Slavetinska,Hrebabecky,Budesinsky
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- Design and synthesis of polycyclic sulfones via Diels-Alder reaction and ring-rearrangement metathesis as key steps
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Here, we describe a new and simple synthetic strategy to various polycyclic sulfones via Diels-Alder reaction and ring-rearrangement metathesis (RRM) as the key steps. This approach delivers tri- and tetracyclic sulfones with six (n = 1), seven (n = 2) or eight-membered (n = 3) fused-ring systems containing trans-ring junctions unlike the conventional all cis-ring junctions generally obtained during the RRM sequence. Interestingly the starting materials used are simple and commercially available.
- Kotha, Sambasivarao,Gunta, Rama
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supporting information
p. 1373 - 1378
(2015/08/24)
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- Fragmentation Patterns in the Gas-Phase Pyrolysis of Some Bi- and Tri-cyclic Sulfolanes Related to the 8-Thiabicyclonon-3-ene 8,8-Dioxide Ring System
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Depending upon the degree of ring strain, the thermal breakdown of cis-8-thiabicyclonon-3-ene 8,8-dioxide 5 and related ring systems in the gas phase follows widely differing pathways.Decomposition of 5 occurs only under forcing conditions, resulting in complete fragmentation of the sulfolane ring to give a benzene and toluene, while pyrolysis of the 2,5-bridged analogues 6-8 proceeds by a retro-Diels-Alder reaction at much lower temperatures to give 1,3-dienes and the decomposition products of 3-sulfolene, buta-1,3-diene and SO2.Epoxidation of the double bond in the compounds results in a marked change in their thermal fragmentation behaviour; only SO2 is lost to produce novel divinyl epoxides.The corresponding N-ethoxycarbonylaziridines, formed by photolysis of the unsaturated sulfones in ethyl azidoformate, undergo extensive decomposition on pyrolysis and do not yield any useful products.The saturated sulfone 28 gives an expected octa-1,7-diene upon flash vacuum pyrolysis (FVP), but only under relatively severe conditions.Three isomeric diene sulfones 30-32 have also been examined and show a varied pattern of reactivity under FVP conditions.
- Aitken, R. Alan,Cadogen, J. I. G.,Gosney, Ian,Newlands, Stephen
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p. 2301 - 2308
(2007/10/02)
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- Une synthese hautement stereoselective de dienes conjugues (E)
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A general method for the preparation of (E) terminal conjugated dienes was developed by the flash thermolysis of 2-substituted 2,5-dihydrothiophene-1,1-dioxides generated by a retro Diels-Alder reaction.This process allows the obtention of conjugated dienes, bearing or not a functionality (alcohols, esters), with an excellent stereoisomeric purity (in general higher than 98percent).An application to the synthesis of (E)-9,11-dodecadien-1-yl acetate, the major component of the sex pheromone of Diparopsis castanea, shows the generality and the efficacy of this method.
- Bloch, R.,Abecassis, J.,Hassan, D.
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p. 2019 - 2024
(2007/10/02)
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- A HIGHLY STEREOSELECTIVE SYNTHESIS OF (E)-1- SUBSTITUTED-1,3-DIENES.
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(E)-1-substituted-1,3-dienes are obtained with high selectivity by the thermal extrusion of SO2 from 2-substituted-2,5-dihidrothiophene-1,1-dioxides generated by a retro Diels-Alder reaction.An application to the synthesis of (E)-9,11-dodecadien-1-yl acetate, a sex pheromone of the red-bollworm moth is described.
- Bloch, R.,Abecassis, J.
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p. 3277 - 3280
(2007/10/02)
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