- Optically Pore Dihydroxy γ-Alkylated γ-Butyrolactones Starting from L-Tartaric Acid: Application to Formal and Total Syntheses of Natural Products
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A general and efficient preparation of epimeric optically pure γ-butyrolactones 2 and 3 is described starting from L-tartaric acid (1). These lactones are well-known to be important building blocks in the syntheses of natural products. L-Tartaric acid (1) was transformed into carbonylated chirons (ketones 4 and aldehyde 5). These chirons, when submitted to highly stereoselective reactions (reduction or organometallic addition), led to epimeric dihydroxy γ-butyrolactones 2 and 3 after lactonization and deprotection steps. The resulting optically pure lactones are precursors of biological compounds and have allowed a total synthesis of L-biopterin and formal syntheses of quercus lactone, dodecanolactone, avenaciolide, and tetrahydrocerulenin.
- Fernandez, Anne-Marie,Plaquevent, Jean-Christophe,Duhamel, Lucette
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- Highly α-selective hydrolysis of α,β-epoxyalcohols using tetrabutylammonium fluoride
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We report a simple method for the highly regio- and stereoselective hydrolysis of α,β-epoxyalcohols. Treatment of enantiopure epoxyalcohols derived from Sharpless epoxidation with TBAF/H2O resulted in exclusive ring opening at the normally disfavored α-position, providing access to arabino- or lyxo-configured triols with full preservation of stereochemical purity. The method was applied in syntheses of 5-deoxy-l-arabinose (26) and a family of bicyclic acetals based on the insect pheromone hydroxybrevicomin (4).
- Mukerjee, Purba,Abid, Mohammed,Schroeder, Frank C.
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supporting information; experimental part
p. 3986 - 3989
(2010/11/04)
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- Studies on the generation of enolate anions from butane-2,3-diacetal protected glycolic acid derivatives and subsequent highly diastereoselective coupling reactions with aldehydes and acid chlorides
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Highly diastereoselective coupling reactions of enolates derived from butane-2,3-diacetal protected glycolic acids 1 and 2 and their alkylated derivatives with aldehydes are reported together with their efficient acid-catalysed deprotection to yield enant
- Ley, Steven V.,Dixon, Darren J.,Guy, Richard T.,Palomero, Maria A.,Polare, Alessandra,Rodriguez, Felix,Sheppard, Tom D.
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p. 3618 - 3627
(2007/10/03)
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- Highly diastereoselective lithium enolate aldol reactions of butane-2,3-diacetal desymmetrized glycolic acid and deprotection to enantiopure anti-2,3-dihydroxy esters.
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[reaction--see text] The butane-2,3-diacetal (BDA) desymmetrized glycolic acid building block 1 undergoes efficient and highly diastereoselective lithium enolate aldol reactions with both aromatic and aliphatic aldehydes to afford, after an acidic methano
- Dixon,Ley,Polara,Sheppard
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p. 3749 - 3752
(2007/10/03)
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- CATALYTIC OSMYLATION OF ELECTRON POOR ALLYLIC ALCOHOLS AND ETHERS. A SYNTHETIC APPROACH TO BRANCHED CHAIN SUGARS
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The catalytic osmylation of electron-poor allylic ethers and alcohols was studied.In the case of γ-alkoxy E-enoates reaction selectivity was found to range from 2:1 to 8:1 in favor of the arabino (2,3-syn - 3,4-anti) product, regardless of the double bond
- Bernardi, Anna,Cardani, Silvia,Scolastico, Carlo,Villa, Roberto
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p. 491 - 502
(2007/10/02)
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- THE PREPARATION OF SOME BROMODEOXY- AND DIBROMODIDEOXY-PENTONOLACTONES
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Treatment of ammonium D-xylonate with hydrogen bromide in acetic acid yields 2,5-dibromo-2,5-dideoxy-D-lyxono-1,4-lactone (2a), whereas similar treatment of potassium D-arabinonate gives 5-bromo-5-deoxy-D-arabinono-1,4-lactone (8a) as the main product.Two isomeric 2,5-dibromo-2,5-dideoxy-1,4-lactones are also formed in minor amounts.Selective hydrogenolysis of 2a affords 5-bromo-2,5-dideoxy-D-threo-pentono-1,4-lactone, while prolonged treatment results in the formation of 3-hydroxypentanoic acid.Similarly, hydrogenolysis of 8a produces a 2,3-dihydroxypentanoic acid together with smaller amounts of 5-deoxy-D-arabinono-1,4-lactone; the latter also results from hydrogenolysis of 5-deoxy-5-iodo-D-arabinono-1,4-lactone with Raney nickel.
- Bock, Klaus,Lundt, Inge,Pedersen, Christian
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