- Nitro alkanes in organic synthesis: An efficient stereoselective synthesis of (+)-trans whisky lactone and (+)-eldanolide from nitro alkane synthons and using bakers' yeast reduction as the key step
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An efficient route using nitroalkane synthon 3a and 3b for the synthesis of optically pure R-(+)-trans whisky lactone, (+)-9 and R-(+)-eldanolide, (+)-10 is described. In a key step, bakers' yeast reduction is employed to get the required chirality.
- Sarmah, Bhabani K.,Barua, Nabin C.
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- Concise enantiodivergent synthesis of (+)- and (-)-trans-quercus lactones
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A concise enantiodivergent total synthesis of (+)- and (-)-quercus lactones from the known tricyclic lactone (+)-1 as a single chiral template was achieved using the diastereoselective nucleophilic addition of organometallic reagents as the key step.
- Suzuki, Katsufumi,Shoji, Muneo,Kobayashi, Eriko,Inomata, Kohei
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- SYNTHETIC METHOD OF EPOGYMNOLACTAM AND INTERMEDIATE THEREOF
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PROBLEM TO BE SOLVED: To provide a synthetic method of an epogymnolactam and an α,β-unsaturated-γ-lactone derivative, which is simple to operate and is more efficient than the conventional synthetic method. SOLUTION: The synthetic method comprises: subjec
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- Organocatalytic sequential α-aminoxylation and cis-Wittig olefination of aldehydes: Synthesis of enantiopure γ-butenolides
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A short route to enantiopure γ-butenolides (up to 99% ee) has been developed from readily available starting materials. The strategy involves a sequential organocatalytic α-aminoxylation followed by cis-Wittig olefination of aldehydes. The utility of this protocol has been demonstrated in the asymmetric synthesis of trans-(+)-cognac lactone with high enantiomeric purity.
- Devalankar, Dattatray A.,Chouthaiwale, Pandurang V.,Sudalai, Arumugam
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experimental part
p. 240 - 244
(2012/06/04)
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- First example of hydrolytic kinetic resolution of acrylate of secondary alcohols by lipase Amano AK
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Lipase Amano AK is found to be extremely efficient catalyst for hydrolytic kinetic resolution of acrylates of secondary alcohols in aqueous phosphate buffer at pH 7.0. Both aliphatic and benzylic secondary alcohols show good to excellent E values.
- Bora, Pranjal P.,Bez, Ghanashyam,Anal, Jasha Momo H.
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p. 270 - 275
(2012/07/03)
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- Organo-catalyzed enantioselective synthesis of some β-silyl γ-alkyl γ-butyrolactones as intermediates for natural products
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The enantioselective synthesis of some β-silyl γ-alkyl γ-butyrolactones has been achieved by an organo-catalyzed Michael addition of enolizable aldehydes onto a silylmethylene malonate followed by a silicon-facilitated Bayer-Villiger oxidation of the β-silyl aldehyde adducts as the key step. γ-Alkyl γ-butenolides were obtained from the β-silyl γ-alkyl γ-butyrolactones by Fleming-Tamao oxidation of the silyl group to a hydroxy group and subsequent elimination. These butenolides are the advanced intermediates of some natural products such as (+)-γ-caprolactone, (+)-methylenolactocine, and (-)-quercus lactone.
- Chowdhury, Raghunath,Ghosh, Sunil K.
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experimental part
p. 1895 - 1900
(2012/01/05)
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- Chemoenzymatic synthesis of optically active γ-alkyl-γ-butenolides
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rac-Hept-1-en-3-ol 4 was subjected to an enantioselective esterification in the presence of Novozyme 435 and vinyl crotonate as the acyl donor to give (3S)-oct-1-en-3-yl crotonate 7 in >99% ee and (3R)-alcohol 4 in 99% ee. The E-value of this enzymatic reaction was found to be >1000. The (S)-crotonic ester 7 was converted by ring-closing metathesis (RCM) using Grubbs' catalyst to give (S)-oct-2-en-4-olide 1 in 96% yield while keeping the high enantiomeric excess.
- Fujii, Mikio,Fukumura, Motonori,Hori, Yumiko,Hirai, Yasuaki,Akita, Hiroyuki,Nakamura, Kaoru,Toriizuka, Kazuo,Ida, Yoshiteru
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p. 2292 - 2298
(2007/10/03)
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- Enantiodivergent syntheses of γ-substituted butenolides with tertiary and quaternary asymmetric centers
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Continuous nucleophilic addition with several organometallic reagents to tricyclic lactone (-)-1 proceeded diastereoselectively. Newly generated tertiary and quaternary asymmetric centers were controlled by the order in which the nucleophilic reagents were added. Using this methodology, enantiodivergent syntheses of several γ-substituted butenolides with tertiary and quaternary asymmetric centers were established from a single chiral material.
- Suzuki, Katsufumi,Inomata, Kohei
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p. 745 - 749
(2007/10/03)
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- Asymmetric dihydroxylation of vinyl sulfones: Routes to enantioenriched α-hydroxyaldehydes and the enantioselective syntheses of furan-2(5H)-ones
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The asymmetric dihydroxylation of α,β-unsaturated sulfones under Sharpless conditions affords enantioenriched α-hydroxyaldehydes in a complex mixture of dimeric species. These mixtures undergo olefination generating the corresponding α,β-unsaturated esters or furan-2(5H)-ones with high levels of enantiomeric excess. The application of this method for the rapid stereoselective synthesis of the furanone natural products; quercus lactone and maritolide, are described.
- Evans, Paul,Leffray, Mélanie
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p. 7973 - 7981
(2007/10/03)
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- Highly Enantioselective Synthesis of Both Enantiomers of γ-Substituted Butenolides by Bakers' Yeast Reduction and Lipase-Catalyzed Hydrolysis. Total Synthesis of (3AS,6aS)-Ethisolide, Whisky Lactone, and (-)-Avenaciolide
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Reduction of 3-chloro-4-oxoalkanoates 5 with bakers' yeast gave (4S)-3-chloro-4-hydroxyalkanoates, which were hydrolyzed and dehydrochlorinated to give (γS)-alkylbutenolides with >96% ee. Reduction of 5 with NaBH4 gave syn-3-chloro-4-hydroxyalkanoate 6. Asymmetric hydrolysis of syn-4-chloro-3-hydroxyalkanoate (±)-10 with lipase afforded (3R,4R)-6 and (3S,4S)-10 with high optical purities. Hydrolysis and dehydrochlorination of (3R,4R)-6 gave (γA)-alkylbutenolides with >85% ee. Total syntheses of (3aS,6aS)-ethisolide, whisky lactone, and (-)-avenaciolide from these butenolides are described.
- Tsuboi, Sadao,Sakamoto, Jun-Ichi,Yamashita, Hiroshi,Sakai, Takashi,Utaka, Masanori
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p. 1102 - 1108
(2007/10/03)
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- Synthesis of Optically Active Butenolides and γ-Lactones by the Sharpless Asymmetric Dihydroxylation of β,γ-Unsaturated Carboxylic Esters
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Keywords: asymmetric synthesis; butenolides; dihydroxylations; furanones; lactones
- Harcken, Christian,Brueckner, Reinhard
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p. 2750 - 2752
(2007/10/03)
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- Concise syntheses of natural γ-butyrolactones, (+)-trans-whisky lactone, (+)-trans-cognac lactone, (-)-methylenolactocin, (+)-nephrosteranic acid, and (+)-roccellaric acid using novel chiral butenolide synthons
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cis-4-Hydroxy-5-(iodomethyl)-4,5-dihydro-2(3H)-furanones (1 and ent-1) were converted by cross-coupling with several Grignard-derived cuprates followed by benzoylation and base-induced elimination into new chiral butenolides 12, 14, ent-14, 20, and 27. The sequential conjugate addition - quenching of these butenolides under complete stereocontrol provided several polysubstituted γ-butyrolactones including flavor components [(±)-trans-whisky lactone (3) and (+)-trans-cognac lactone (4)], the antitumor antibiotic lactone (-)-methylenolactocin (5), and lichen components [(+)-nephrosteranic acid (7) and (+)-roccellaric acid (8)].
- Takahata,Uchida,Momose
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p. 5628 - 5633
(2007/10/03)
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- New Entry to Chiral Butenolide Synthons. Application to Expeditious Syntheses of (+)-Nephrosteranic Acid, (+)-trans-Whisky Lactone, and (+)-trans-Cognac Lactone
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A new entry to chiral butenolide synthons starting with iodolactonization of the readily available, homochiral N-benzyl-N-methyl-3-hydroxy-4-pentenamide (1) and its application to the syntheses of (+)-nephrosteranic acid (5), (+)-trans-whisky lactone (6), and (+)-trans-cognac lactone (7) are described.
- Takahata, Hiroki,Ushida, Yasuhiro,Momose, Takefumi
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p. 4123 - 4124
(2007/10/02)
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- Novel Asymetric Synthesis of γ-Alkylated Lactones via Successive Alkylation and Reduction of Chiral Cyclic Imides with C2-Symmetry
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Consecutive treatment of chiral cyclic imides containing a C2-axis of symmetry with Grignard reagents and sodium borohydride followed by cyclization furnished γ-alkylated lactones with high diastereoselectivity.Products were converted to synthetically useful R-butenolides after removal of the chirality inducing groups.
- Yoda, Hidemi,Shirakawa, Koji,Takabe, Kunihiko
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p. 489 - 490
(2007/10/02)
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- Pure Enantiomers from Retro-Diels-Alder Processes
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Diastereoselective and regioselective transformations of cycloadducts to enantiomerically pure cyclopentadienes are reported.Retro-Diels-Alder processes finally give rise to pure enantiomers in high yield.
- Beckmann, Marion,Hildebrandt, Hinrich,Winterfeldt, Ekkehard
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p. 335 - 345
(2007/10/02)
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- Lewis Acid-Mediated Carbon-Carbon Bond Forming Reaction Using the Pummerer Rearrangement Products from Chiral β-Hydroxy Sulfoxides
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The Pummerer rearrangement products, obtained from (RC,RS)-β-hydroxy sulfoxide derivatives, react with silyl enol ethers or a ketene silyl acetal in the presence of ZnBr2 to give the γ-hydroxy-β-tolylthio carbonyl derivatives, which, in turn, are converted to optically pure (E)-γ-hydroxy-α,β-unsaturated carbonyl compounds and 5-substituted 2(5H)-furanones, respectively.
- Kosugi, Hiroshi,Watanabe, Yasuyuki,Uda, Hisashi
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p. 1865 - 1868
(2007/10/02)
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