- A 1H and 13C NMR Study of the Structure of Sulfur-Stabilized Lithiated Allylic Carbanions
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NMR studies of the solution structures of lithiated (E)-1-(t-butylthio)but-2-ene (4) and lithiated (E)-1-(phenylthio)but-2-ene (6) are reported.The structure of lithiated (E)-1-(t-butylthio)but-2-ene (4) is best described as a transoid carbanion with the allylic carbons C1, C2, and C3 having intermediate sp2-sp3 hybridization.In (4) the heteroatom and non-allylic substituent do not play any significant role in carbanion stabilization.Lithiated (E)-1-(phenylthio)but-2-ene (6) differs from (4) in that it exhibits cis geometry about the C1-C2 bond and the phenylthio group participates in helping to stabilize allylic charge.There is a discrepancy between the geometry about the C1-C2 bond in the solution and solid structures of (4) in the presence of TMEDA.
- Glendenning, Lionel,Field, Leslie D.,Haynes, Richard K.
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p. 2739 - 2750
(2007/10/03)
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- The Preparation of Some β-Sulfonylacrylate Thioesters and β-Sulfonylvinyl Ketones
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β-Sulfonylacrylate phenyl and t-butyl thioesters, and β-sulfonylvinyl ketones have been prepared by oxidation of the corresponding β-aryl- and β-alkyl-thio compounds.In one case the β-sulfonylvinyl ketone was obtained from an epoxy sulfone.The β-aryl- and β-alkyl-thio compounds were obtained by chlorination-dehydrochlorination of saturated precursors.The reactions of 3-(phenylthio)propionyl chloride with organocadmium and Grignard reagents were used to prepare some of the saturated precursors of the β-sulfonylvinyl ketones.
- Haynes, Richard K.,Vonwiller, Simone C.,Stokes, John P.,Merlino, Louisa M.
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p. 881 - 895
(2007/10/02)
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- The Stabilization due to the Methyl Group in RSCH2CH=CHCH3
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Equilibrium constants for the isomerization reactions have been measured and the energy differences of the isomers have been calculated.According to these results a methyl group stabilizes the double bond by 12.8(5) kJ mol-1 and the RSCH2CH3 cis interaction is 3.7(4) kJ mol-1.
- Kimmelma, Reijo
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p. 344 - 347
(2007/10/02)
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- Application du rearrangement de Claisen aux -1 alcen-1(Z) ols-3. Syntheses d'alcadien-2(E),4(E) oates d'ethyle et de (p.toluenesulfonylamino)-5 alcen-3(E) ols-1
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The acid catalysed reaction between 1--1(Z)-alken-3-ols 1 and ethyl orthoacetate takes place via a Claisen rearrangement to give stereoselectively the ethyl-3-(1',1'-dimethylethyl)thio-4(E)-alkenoates 2a, b, c.Oxone oxidation converts these sulfide-esters 2 into the corresponding sulfone-esters 6a, b, c, which on treatment with sodium carbonate give the ethyl 2(E),4(E) alkadienoates 7a, b, c.Treatment of the sulfide-esters 2 with chloramine T yields compounds 10a, b, c through a sigmatropic rearrangement of the intermediate N-tosyl-sulfimines.These compounds 10 are reduced by DIBAL-H to the 5-(p.toluenesulfonylamino)-3(E) alken-1-ols 11a, b, c.
- Lorne, Robert,Julia, Sylvestre A.
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p. 317 - 324
(2007/10/02)
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