- Synthesis of enantiomerically pure 3-butene-1,2-diol derivatives via a Sharpless asymmetric epoxidation route
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A short enantiospecific synthesis of the butenediol monotosylates (1,2), the epoxybutanediol monotosylates (3,4) and the epoxybutenes (5,6) is described.
- Neagu,Hase
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- Enzyme-mediated enantioselective hydrolysis of 1,2-diol monotosylate derivatives bearing an unsaturated substituent
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We have succeeded in the easy preparation of optically active 1,2-diol monotosylates bearing an unsaturated substituent via enzymatic hydrolysis. Lipase PS quickly catalyzes the hydrolyses of 2-acetoxybut-3-enyl tosylate, which has a double bond, and 2-acetoxybut-3-ynyl tosylate, which has a triple bond, with excellent enantioselectivity to afford the corresponding optically active compounds. The reaction is also applicable to acetates with a longer chain, which has a double bond at the terminus. To demonstrate the applicability of this method, enantiomerically pure (R)-massoialactone, a natural coconut flavor, has been synthesized from racemic 2-acetoxypent-4-enyl tosylate in several steps. Furthermore, the enzyme can recognize the stereochemistry of olefins, and the (Z)-alkenyl structure is more suitable for the enantioselective hydrolysis than the (E)-isomer.
- Matsumoto,Oohana,Hashimoto,Usuda,Shimoda,Ohshima,Suzuki,Togawa
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p. 3981 - 3988
(2018/06/15)
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- Synthesis of the C1-C15 fragment of elaiolide
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The synthesis of the C1-C15 fragment of elaiolide was achieved by successfully utilizing the desymmetrization strategy, zirconium catalyzed C-C bond formation and double stereodifferentiating aldol reactions. The Royal Society of Chemistry.
- Jhillu Singh, Yadav,Rao Yarrapothu, Gangadhara,Vemula, Rajender
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- Stereoselective preparation of a key intermediate toward the synthesis of nelfinavir
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A stereoselective synthesis of an intermediate that can be elaborated into the potent HTV-protease inhibitor, nelfinavir, is described. The key step of the reaction sequence is the stereoselective preparation of a bromosulfonamide from an olefin using the
- Raghavan, Sadagopan,Kumar, Ch. Naveen
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experimental part
p. 821 - 828
(2011/08/09)
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- Three step synthesis of single diastereoisomers of the vicinal trifluoro motif
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A three step route to single diastereoisomers of the vicinal trifluoromethyl motif is described. The route starts from either syn- or anti-α,β-epoxy alcohols and takes a direct approach in that each of the three steps introduces a fluorine atom in a regio- and stereospecific manner. Starting from either the syn- or the anti-α,β-epoxy alcohol, stereospecific reactions generate two separate diastereoisomeric series of this motif. The route is a significant improvement on an earlier six step strategy.
- Brunet, Vincent A.,Slawin, Alexandra M. Z.,O'Hagan, David
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supporting information; experimental part
(2010/04/22)
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- New synthesis of sn-1,2- and sn-2,3-O-diacylglycerols application to the synthesis of enantiopure phosphonates analogous to triglycerides: A new class of inhibitors of lipases
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Phosphonate compounds mimic the first transition state occurring during enzymatic carboxyester hydrolysis of natural substrates by forming a covalent bond with the catalytic serine. However, until now the organophosphorus compounds used in the inhibition studies more or less resembled a natural triglyceride substrate. In order to elucidate the interfacial activation and the mechanism of action of lipases, specific inhibitors need to be prepared. To achieve this goal, enantiomerically pure sn-1,2- and sn-2,3O- didecanoylglycerol compounds were prepared - starting from a C-4 chiral synthon, 3-buten-1,2-diol - and treated with n-pentylphosphonic dichloride and p-nitrophenol to afford the corresponding diastereomeric phosphonates, which were acylglycerol analogs. Subsequent separation of each of the phosphonate diastereomers A/B or ent-A/ent-B, performed by HPLC, led to four enantiopure stereoisomers that will be investigated as inhibitors of Human Pancreatic Lipase (HPL) and Human Gastric Lipase (HGL) using the monomolecular film technique.
- Marguet, Frank,Cavalier, Jean-Francois,Verger, Robert,Buono, Gerard
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p. 1671 - 1678
(2007/10/03)
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- Amine assisted enzymatic esterification of 1,2-diol monotosylates
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The enzymatic esterification of 1,2-diol monotosylates in organic solvent under standard conditions often fails to achieve the desired 50% conversion due to enzyme inactivation by acidic contaminants. The inclusion of an amine affords rapid conversion to
- Boaz,Zimmerman
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p. 153 - 156
(2007/10/02)
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- Alcohol-ester sparation by reaction with acetate
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A process is disclosed for the isolation of an enantiomerically enriched alcohol from a first mixture of an enantiomerically enriched 1-arylsulfonate-2 -hydroxy-3-butene and an enantiomerically enriched 1 -arylsulfonate- 2-acyloxy-3-butene. The process includes the steps of: (a) contacting the mixture with a reagent capable of reacting with said 1-arylsulfonate-2-hydroxy-3-butene to remove the arylsulfonate group and produce a mixture of dihydroxybutene monoesters thereby forming a second mixture containing said dihydroxybutene monoesters and unreacted enantiomerically enriched 1-arylsulfonate-2-acyloxy-3-butene (b) contacting the second mixture with reagents capable of hydrolyzing all of the acyl groups in said mixture to hydroxy groups so as to produce a third mixture comprising 1,2-dihydroxy-3-butenes and enantiomerically enriched 1-arylsulfonate-2-hydroxy-3 -butene; (c) washing said third mixture with water so as to remove said 1,2-dihydroxy-3-butenes.
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- Palladium catalyzed cyclizations of enantiomerically pure acyclic 4-acetoxy-2,8-nonadienes: Efficient chirality transfer
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S-4-Acetoxy-6-aza-2,8-nonadienes 9 and 11 were subjected to Pd(0)-catalyzed cyclizations. The S,E-acetate 9 gave exclusively S,E-pyrrolidine 12, whereas the antipodal product R,E-12 was formed from the S,Z-precursor 11 (Scheme 3). X-ray-diffraction analys
- Oppolzer, Wolfgang,Birkinshaw, Timothy N.,Bernardinelli, Gerald
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p. 6995 - 6998
(2007/10/02)
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