- CONFORMATIONAL STUDIES OF 7-MEMBERED CYCLIC SULFITES. 3-OXO-2,4,3-DIOXATHIEPIN AND 3-OXO-2,4,3-BENZODIOXATHIEPIN
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The conformational and dynamic properties of the 7-membered cyclic sulfites 1 and 2 were investigated by (1)H and (13)C DNMR as well as by IR spectroscopy.Compound 1 showed two spectral modifications at low temperature for both (1)H (100 MHz) and (13)C (22.6 MHz) spectra while for compound 2 a single (1)H spectral change has been observed and resolved at 300 MHz.Analysis of the low temperature NMR spectra together with the IR frequencies for the stretching vibration of the S=O bond indicate that 1 exists as a 1:1 mixture of C-a and TB conformations in CHF2Cl.Less polar solvents increase the proportion of the C-a form.In contrast, compound 2 is found to exist very predominantly as the TB form in CHF2Cl at -160 deg, whereas in the less polar CCl4 solvent a small amount of C-a form is found to be present at room temperature from the IR data.The conformational and dynamic properties determined for 1 and 2 are discussed in light of current theories relating to n -> ?* stereoelectronic lone pair donation and dipole-dipole interactions.Furthermore the results for 1 and 2 are used as the basis for a new conformational interpretation of published IR data for dimethyl sulfite.Finally, the differences in properties of 1 and 2 are discussed.
- Faucher, H.,Guimaraes, A. C.,Robert, J. B.,Sauriol, F.,St-Jacques, M.
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- Synthesis of highly substituted tetrahydrofurans by catalytic polar-radical-crossover cycloadditions of alkenes and alkenols
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Light up my ring: The title reaction is catalyzed by an acridinium/phenylmalononitrile photoredox system. A variety of readily available olefins and unsaturated alcohols can be employed to furnish tetrahydrofuran adducts with complete regiocontrol and up to four contiguous stereogenic centers.
- Grandjean, Jean-Marc M.,Nicewicz, David A.
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supporting information
p. 3967 - 3971
(2013/05/09)
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- Thionyl chloride-benzotriazole in methylene chloride: A convenient solution for conversion of alcohols and carboxylic acids expeditiously into alkyl chlorides and acid chlorides by simple titration
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A solution of 1:1 equivalent of thionyl chloride and benzotriazole in dry methylene chloride efficiently transforms alcohols and carboxylic acids into the corresponding alkyl chlorides and acid chlorides respectively at room temperature, with excellent yields by simple titration.
- Chaudhari, Sachin S.,Akamanchi, Krishnacharya G.
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p. 1763 - 1765
(2007/10/03)
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- Reaction of diethylaminosulfur trifluoride with diols
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Diethylaminosulfur trifluoride (DAST) reacts with dialcohols to give difluorides, sulfite esters or cyclic ethers depending on the number of carbons separating the two alcohol groups.Vicinal and 1,3-diols give large amounts of sulfite ester products while butane-1,4-diol gives almost exclusively the cyclic ether tetrahydrofuran.Terminal dialcohols longer than four carbons give primarily difluoride products.Semiempirical calculations indicate a preference for cyclic intermediates when four or less carbons separate the two alcohol moieties.These cyclic intermediates lead directly to the cyclic ethers and sulfite ester products.
- Shellhamer, Dale F.,Anstine, D. Timothy,Gallego, Kelly M.,Ganesh, Brian R.,Hanson, Aaron A.,et al.
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p. 861 - 866
(2007/10/02)
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- Unsaturated Cyclic Sulfites. I. Synthesis and Condensation with Terminal Acetylene
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Cyclic unsaturated sulfite Δ5-1,3-dioxa-2-thialepin-2-oxide synthesized from (Z)-2-butene-1,4-diol was studied in the condensation with 1-heptyne.The direction of the reaction strongly depends on the conditions.The reaction resulted in (Z)/(E)-2-undecene-5-yn-1-ol and a by-product, 3-(hydroxymethyl)-1-decene-4-yne. - Key words: cyclic unsaturated sulfite; Δ5-1,3-dioxa-2-thialepin-2-oxide; (Z)-2-butene-1,4-diol; (Z)-2-undecene-5-yn-1-ol; (E)-2-undecene-5-yn-1-ol
- Kochev, D. M.,Myagkova, G. I.
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p. 700 - 701
(2007/10/03)
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