- The synthesis of chiral β-ketosulfoxides by enantioselective oxidation and their stereocontrolled reduction to β-hydroxysulfoxides
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Various chiral non-racemic β-ketosulfoxides, a class of compounds frequently used in asymmetric synthesis, were prepared in good yields by tert-butyl hydroperoxide oxidation of the corresponding sulfides in the presence of a complex between titanium and (
- Cardellicchio, Cosimo,Omar, Omar Hassan,Naso, Francesco,Capozzi, Maria Annunziata M.,Capitelli, Francesco,Bertolasi, Valerio
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p. 223 - 229
(2007/10/03)
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- Highly enantiomeric purity conversion of α-sulfinyl oximes and α-sulfinyl hydrazones to the corresponding β-keto sulfoxides with butyltriphenylphosphonium periodate (BUTPPPI)
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Butyltriphenylphosphonium periodate (Ph3P+BuIO 4-)1 is readily prepared as a white solid from butyltriphenylphosphonium chloride, performs conversion of α-sulfinyl oximes (2) and α-sulfinyl hydrazones (4) to the
- Hajipour,Ruoho
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p. 2653 - 2657
(2007/10/03)
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- A new and general synthesis of chiral β-ketosulfoxides by reaction of (+)-(R)-methyl p-tolyl sulfoxide with nitriles
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The nitrile functional group is efficiently transformed into the β-ketosulfoxide moiety by reaction with the anion formed from (+)-(R)-methyl p-tolyl sulfoxide and aqueous acidic work-up of the reaction.
- Vleggaar, Robert,Zeevaart, Jacob G.
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p. 9301 - 9303
(2007/10/03)
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- Alternative approach to the synthesis of optically active β-keto sulfoxides by furylhydroperoxides enantioselective oxidations
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Enantiomerically enriched β-keto sulfoxides are obtainable by an alternative method to the classical reaction of the enantiomerically pure α- sulfinyl anion with esters or by Anderson's synthesis, through Sharpless modified kinetic resolution of racemic β-keto sulfoxides. High e.e.s are achieved by combining asymmetric oxidation and kinetic resolution using furylhydroperoxides as oxidants.
- Lattanzi, Alessandra,Bonadies, Francesco,Schiavo, Annamaria,Scettri, Arrigo
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p. 2619 - 2625
(2007/10/03)
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- Studies on chiral organosulfur compounds. III. Lewis acid-catalyzed intramolecular asymmetric pericyclic reactions of chiral α-acetyl and methoxycarbonylvinylic sulfoxides
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A chiral α-sulfinyl α,β-unsaturated ketone served as a good chiral diene or enophile in intramolecular Lewis acid-catalyzed asymmetric pericyclic reactions, giving hetero-Diels-Alder reaction products, together with ene reaction products in some cases, in
- Hiroi,Umemura,Fujisawa
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p. 666 - 671
(2007/10/02)
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- Synthetic studies on spiroketal natural products. IV. A stereoselective synthesis of (3S,5S,6R,9R,R(S))-3-benzyloxymethyl-9-hydroxymethyl-5-(p-tolyl)sulfin yl-1,7-dioxaspiro[5.5]undecane, a key intermediate for talaromycins
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A dioxaspiro compound (4), a common intermediate for the synthesis of talaromycin A (1) and (-)-talaromycin B (2), was synthesized by two routes utilizing two kinds of asymmetric recognition of prochiral 1,3-diols controlled by sulfinyl chirality, that is, firstly by acid promoted diastereoselective C-O bond fission of the bicyclic acetal (7) to give the dihydropyran derivative (6), which has an S-hydroxymethyl group at the C3-position (7 → 6), and secondly by diastereoselective intramolecular Michael addition of the diol (5), in which the three chiral centers at C5, C6, C9 were constructed in one step (5 → 4).
- Iwata,Maezaki,Hattori,Fujita,Moritani,Takemoto,Tanaka,Imanishi
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p. 339 - 345
(2007/10/02)
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- Synthesis of optically active β,γ-diketo-p-tolylsulfoxides
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Chiral β,γ-diketo-p-tolylsulfoxides were prepared in high yields by three different methods: 1,3-diketone dianions on menthyl (-)(S) p-tolylsulfinate, methyl (+)(R) p-tolylsulfoxide anion on β-ketoester and finally (+)(R) p-tolylsulfinyl 2-propanone dianion on carboxylic ester,
- Solladie, Guy,Ghiatou, Nasser
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- 1,3-Asymmetric Induction in the Reduction of α-Alkyl β-Ketosulfoxides with DIBAL/ZnBr2
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The highly stereoselective reduction of chiral α-alkyl β-ketosulfoxides with DIBAL/ZnBr2 is governed by the configuration at the sulfur (1,3-induction) and not by that of the C-α (1,2-induction) as it has been previously reported.This fact considerably in
- Barros, David,Carreno, M. Carmen,Ruano, Jose L. Garcia,Maestro, M. Carmen
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p. 2733 - 2736
(2007/10/02)
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- Enantioselective oxidation of sulphides to sulphoxides in the presence of bovine serum albumin
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In situ generated dioxiranes oxidize a series of prochiral sulphides to the corresponding sulphoxides with enantiomeric excess (e.e.) up to 89%, when bovine serum albumin (BSA) is used as chiral auxiliary. The degree of enantioselectivity, as well as yield and reaction times, depend upon the nature of the dioxirane. These are compared with enantioselectivities attainable for the same transformations by using peroxomonosulfate alone, i.e. in the absence of ketone. In the oxidation of prochiral keto sulphides (wherein the carbonyl functionality serves as precursor of dioxirane) with peroxomonosulfate, optically active keto sulphoxides are isolated in satisfactory chemical and optical yield (up to e.e. 84%).
- Colonna,Gaggero,Leone,Pasta
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p. 8385 - 8398
(2007/10/02)
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- ASYMMETRIC FUNCTIONALIZATION AT A PROCHIRAL CARBON CENTER BY THE AID OF SULFINYL CHIRALITY: A SELECTIVE FORMATION OF 6-SUBSTITUTED (3R,SS)- AND (3S,SS)-3-HYDROXYMETHYL-3,4-DIHYDRO-5-(p-TOLYL)SULFINYL-2H-PYRANS
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A successful asymmetric functionalization of prochiral gem-bis(hydroxymethyl) groups has been achieved by the aid of a sulfinyl chirality.
- Iwata, Chuzo,Fujita, Masahiro,Moritani, Yasunori,Sugiyama, Kenji,Hattori, Kohji,Imanishi, Takeshi
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p. 3131 - 3134
(2007/10/02)
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- Preparation of Chiral β-Hydroxyketones by Aldol-type Condensation of Chiral p-Tolylsulfinylmethyl Ketones
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Chiral β-hydroxyketones 7 with fair e.e. were prepared by treating newly prepared optically pure p-tolylsulfinylmethyl ketones 4 with t-butylmagnesium bromide and aldehydes 5 followed by desulfurization with aluminium amalgam.
- Schneider, Fernand,Simon, Roland
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p. 582 - 584
(2007/10/02)
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