- Stereochemical control in the synthesis of tetrahydrofurans by cyclisation of diols with [1,2]phenylsulfanyl migration
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Acid catalysed rearrangement of a series of 4-PhS-1,3-diols with toluene-p-sulfonic acid in benzene gives stereospecifically substituted 3-PhS-tetrahydrofurans in excellent yield via a [1,2]-SPh shift. We comment on the structural variation at both the migration origin and terminus on the outcome of the title reaction and define its limits.
- Aggarwal, Varinder K.,Eames, Jason,Villa, Maria-Jesus,McIntyre, Sara,Sansbury, Francis H.,Warren, Stuart
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p. 532 - 546
(2007/10/03)
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- Additive Pummerer reactions of vinylic sulfoxides. Synthesis of γ-hydroxy-α,β-unsaturated esters, α-hydroxyketones, and 2-phenylsulfenyl aldehydes and primary alcohols
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Treatment of β-monosubstituted vinylic sulfoxides 1 with trifluoroacetic anhydride in dichloromethane gave excellent yields of 1,2-bis(trifluoroacetoxy)thioethers 6. Mildly basic methanolysis of 2-alkyl-substituted 6 gave α-hydroxyaldehydes 11 as monomer-dimer mixtures; similar treatment of the 2-aryl analogues afforded aryl (hydroxymethyl) ketones 12. Compounds 11 underwent Wittig reactions with methoxycarbonylmethylenetriphenylphosphorane to give high yields of γ-hydroxy-α,β-unsaturated esters 13, predominantly as the E-isomers. β-Monosubstituted vinylic sulfoxides 1 possessing a β-aryl group, and β-disubstituted vinylic sulfoxides 3 reacted with trifluoromethanesulfonic anhydride-sodium acetate in acetic anhydride to give 2-(phenylsulfenyl) acylals 14. These gave 2-phenylsulfenyl aldehydes 15 upon basic methanolysis, and the corresponding primary alcohols 16 on reduction with sodium borohydride. Reaction of both geometric isomers of enantiomerically pure vinylic sulfoxide 1o with TFAA gave racemic 6o as a mixture of diastereomers. Reaction of optically pure (E)- and (Z)-1p with trifluoromethanesulfonic anhydride-sodium acetate in acetic anhydride gave acylal 19 in 10.5 and 23% e.e., respectively.
- Craig, Donald,Daniels, Kevin,MacKenzie, A. Roderick
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p. 11263 - 11304
(2007/10/02)
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- Pyridine derivatives
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The invention concerns novel, pharmaceutically useful 1,3-dioxane alkenoic acid derivatives of the formula I containing a pyridyl moiety at position 4 of the dioxane ring and in which the groups at positions 2, 4 and 5 have cis-relative stereochemistry, X is hydrogen, alkoxy or hydroxy, Y is vinylene, n is 1 or 2, A1 is alkylene, the substituents R1 and R2 at position 2 of the dioxane ring have a variety of values defined hereinafter, and R4 is hydroxy, a physiologically acceptable alcohol residue or alkanesulphonamido, and the pharmaceutically acceptable salts thereof. The invention also includes processes for the manufacture and use of the acid derivatives as well as pharmaceutical compositions for therapeutic use in one or more of a variety of diseases such as ischaemic heart disease, cerebrovascular disease, asthmatic disease and/or inflammatory disease.
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- Additive Pummerer reactions of vinylic sulphoxides. Synthesis of 2-(phenylsulphenyl) aldehydes and primary alcohols
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Reaction in acetic anhydride solution of α,β-unsaturated sulphoxides 1 with sodium acetate and triflic anhydride gives 2-(phenylsulphenyl) acylals 4. Basic methanolysis of 4 gives 2-(phenylsulphenyl) aldehydes 8, whilst reduction gives directly 2-(phenylsulphenyl) primary alcohols 9.
- Craig,Daniels,MacKenzie
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p. 6973 - 6976
(2007/10/02)
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- A novel synthesis of α-(phenylthio)aldehydes
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Addition of methoxy(phenylthio)methyllithium to ketones, followed by rearrangement of the adducts, provides a new method for the preparation of α-(phenylthio)aldehydes.The rearrangement is stereospecific.
- Jansen, B. J. M.,Peperzak, R. M.,Groot, Ae. de
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p. 489 - 494
(2007/10/02)
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- Conversion of Tosylhydrazones of α-Halogeno-aldehydes and -ketones into the Corresponding Phenylthio- and Phenylseleno-derivatives
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The tosylhydrazones of 2-chlorocyclohexanone, 2-chlorocyclopentanone, 1-chloropropanone, phenacyl chloride, 2-bromoheptanal and 2-bromo-2-methylpropanal (1), (5a),(7a),(8b), and (9b), respectively, reacted rapidly with thiophenol and an excess of triethylamine in tetrahydrofuran at -78 deg C to give the corresponding α-phenylthio-substituted tosylhydrazones (3a), (5b), (7b), (8c), and (9c) in good yields.The α-phenylseleno-substituted tosylhydrazones (3b),(5c), (6c), (8d), and (9d) were similarly prepared, in satisfactory yields, by treating the corresponding α-halogeno-substituted tosylhydrazones with benzeneselenol and an excess of triethylamine.Several α-phenylthio-substituted carbonyl compounds and 2-phenylselenocyclohexanone (4b) were regenerated from the corresponding tosylhydrazones in good yields.
- Reese, Colin B.,Sanders, H. Paul
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p. 2719 - 2724
(2007/10/02)
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- A NOVEL SYNTHESIS OF α-SULFENYLATED ALDEHYDES
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Ketones are converted into α-sulfenylated aldehydes with addition of one carbon atom via reaction with methoxyphenylthiomethyllithium followed by rearrangement of the adducts.
- Groot, Ae. de,Jansen, B. J. M.
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p. 887 - 888
(2007/10/02)
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