- Intermolecular Stereoselective Pummerer Reactions of 4-(p-Chlorophenyl)thiane 1-Oxides and trans-1-Thiadecalin 1-Oxides and 2-Thiadecalin 2-Oxides with Acetic Anhydride
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The Pummerer reactions of cnformationally fixed 4-(p-chlorophenyl)thiane 1-oxides and trans-1-thiadecalin 1-oxides and trans-2-thiadecalin 2-oxides with acetic anhydride are either stereoselective or stereospecific, both in the absence and in the presence of a scavenger of acetic acid formed, such as dicyclohexylcarbodiimide (DCC) or 2,6-lutidine.However, the 18O-tracer experiments with the 18O-labeled sulfoxide revealed the reaction to be an intermolecular rearrangement, while the kinetic experiment with α-deuterated 4-(p-chlorophenyl)thiane 1-oxides gave sizable values of kinetic isotope effect, i.e., 2.8 for the cis isomer and 3.4 for the trans isomer.In the reaction of 4-arylthiane 1-oxides with acetic anhydride, the thermodynamically controlled product is axial 2-acetoxy-4-(p-chlorophenyl)thiane while the kinetically controlled product is the equatorial isomer which is formed in the presence of the acid scavenger, DCC.In the Pummerer reaction of the thiadecalins S-oxides the equatorial α-acetoxy sulfides are the preferential products, however, the isomer preference is more pronounced in the reaction with DCC.These observations, along with other pertinent data seem to suggest that the rate-determining step in the Pummerer reaction of these simple heterocyclic sulfoxides is E2 elimination of acetic acid from the acetoxysulfonium intermediates.
- Oae, Shigeru,Itoh, Osamu,Numata, Tatsuo,Yoshimura, Toshiaki
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- Stereochemistry of Oxygenation of Organic Sulphides with Pig Liver Microsomal FAD-containing Mono-oxygenase: Comparison with Cytochrome P-450PB Oxidations
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The enantiotopic differentiating ability of pig liver microsomal FAD-containing mono-oxygenase (EC 1.14.13.8) in the oxygenation of nine unsymmetrical sulphides has been investigated.By this enzymatic oxygenation, the sulphides are converted into the corr
- Fujimori, Ken,Matsuura, Takaharu,Mikami, Akihiro,Watanabe, Yoshihito,Oae, Shigeru,Iyanagi, Takashi
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p. 1435 - 1440
(2007/10/02)
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- STEREOSELECTIVE ELECTROOXIDATION OF A THIANE TO THE CORRESPONDING THIANE OXIDE
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Electrochemical oxidation of 4-(p-chlorophenyl)thiane in aqueous organic solvents gave selectively the trans-sulfoxyde by bromium ion mediation.A preferential formation of the cis-sulfoxyde was attained under acidic electrolyses.
- Kimura, Makoto,Kuriki, Nobuo,Inaishi, Morio,Sawaki, Yasuhiko
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p. 4665 - 4668
(2007/10/02)
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- THE MECHANISTIC MODE OF OXIDATION OF SUBSTITUTED N,N-DIMETHYLANILINES, THIOANISOLES, AND METHYL PHENYL SULFOXIDES BY 5-ETHYL-4a-HYDROPEROXY-3-METHYL-LUMIFLAVIN (4a-FlEt-OOH)
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In the oxidation of the title compounds, 5-ethyl-4a-hydroperoxy-3-methyl-lumiflavin (4a-FlEt-OOH), was found to be an electrophilic oxidant similar to m-chloroperoxybenzoic acid.However, the stereoselectivity of the oxidation of cyclic sulfides to the corresponding sulfoxides by 4a-FlEt-OOH was less pronounced than that of the oxygenation with flavin-containing monooxygenase.
- Oae, Shigeru,Asada, Kaoru,Yoshimura, Toshiaki
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p. 1265 - 1268
(2007/10/02)
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- SELECTIVE OXIDATION OF SULFIDE BY ArIO-METALLOPORPHYRIN SYSTEM - AN ENZYME MODEL S-OXIDATION
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Various sulfides are easily oxidized selectively to the corresponding sulfoxides in quantitative yields by iodosylarene (ArIO) catalyzed by metalloporphyrin (TPPM(III)Cl (M= Fe, Mn)).The oxidation system is demonstrated to be a possible model for monooxygenase in the study of the stereochemistry of these sulfoxides.Metalloporphyrin-iodosylarene can initially equilibrate with the oxometalloporphyrin (TPPM(V)=O*Cl) formed in situ.The initial process may involve one-electron transfer from the sulfide to the intermediate oxometalloporphyrin followed by coupling of two resulting charged products, and/or nucleophilic attack of sulfide on oxometalloporphyrin oxygen.The overall reactions are depicted by paths with different electron demands from the results of Hammett plots.
- Takata, Toshikazu,Tajima, Reiko,Ando, Wataru
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