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1.
Emelyne Voss Axelle Arrault Jacques Bodiguel Brigitte Jamart-Grgoire 《Tetrahedron: Asymmetry》2009,20(15):1809-1812
The synthesis of enantiomerically pure orthogonally protected δ-azaproline has been performed in five steps including two successive Mitsunobu reactions starting from benzyloxycarbonylaminophthalimide and the (R)-α-hydroxy-γ-butyrolactone. 相似文献
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E. R. Latypova A. V. Bannova R. R. Muslukhov M. A. Shutova R. F. Talipov G. Yu. Ishmuratov 《Chemistry of Natural Compounds》2010,46(3):370-372
New capabilities for the synthetic use of (R)-4-menthen-3-one were demonstrated using as examples (3S)-methylundec- and (2S)-methyldec-1-ylbromides, key synthons for (S,S,S)-diprionylacetate (sex pheromone of pine sawflies of genera Diprion and Neodiprion). 相似文献
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Synthesis of (2R,3S,4S)-4-aryl-3-hydroxyprolinols has been established starting from 2-benzyloxymethylpyrrolidin-2-one framework, which is derived from commercially available trans-(2S,4R)-4-hydroxyproline. The single diastereomer having a trans–cis relative configuration with C2 and C3 and C3 and C4 is constructed in two one-pot functional group transformations of Grignard addition/dehydration and epoxidation/isomerization as the key steps in moderate yield. 相似文献
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Vinyl substituted (1R,2S)-amino alcohols 5 were obtained by addition of vinyl magnesium bromide to the corresponding cyanohydrin O-trimethylsilyl ethers (R)-2. The O- and N-protected vinyl amino alcohols 6 were ozonized at −78°C in methanol yielding (1R,2S)-2-amino-1,3-diols7 in high enantiomeric and diastereomeric excesses. For purification, compounds 7 in some cases were acetylated to give the derivatives (1R,2S)-8. Racemic 6a was converted by oxidative ozonolysis at −78°C in methanolic NaOH solution to the corresponding methyl N-acetyl-β-hydroxy propanoate 9a. The configuration of (1R,2S)-8a was confirmed by x-ray crystallographic analysis. 相似文献
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Organocatalytic enantioselective synthesis of β-blockers: (S)-propranolol and (S)-naftopidil 总被引:1,自引:0,他引:1
Sharad P. Panchgalle Rohitkumar G. Gore Subhash P. Chavan Uttam R. Kalkote 《Tetrahedron: Asymmetry》2009,20(15):1767-1770
An efficient enantioselective synthesis of β-adrenergic blockers (S)-propranolol and (S)-naftopidil with >98% ee using an l-proline-catalyzed α-aminoxylation of an aldehyde as a key step is described. 相似文献
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An easy and efficient one-pot reaction from readily available 2-(N-Cbz) aminocyclobutanone selectively gave, by means of an asymmetric Strecker synthesis in the presence of a chiral benzylic amine, the thermodynamic 1,2-diamino nitriles. Basic hydrolysis, cleavage of the benzylic group and acidic hydrolysis of the resulting trans-1,2-diaminocyclobutanecarbonitrile gave, in a four-step sequence from the ketone, (1S,2S)- or (1R,2R)-1,2-diaminocyclobutanecarboxylic acid, ornithine derivatives. The absolute configuration has been established by X-ray analysis of the corresponding trans-diamino amide. 相似文献
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Dichlorocobalt(III) complexes of (2S,5S,9S)-trimethyltriethylenetetraamine (L1) and (2S,5R,9S)-trimethyltriethylenetetraamine (L2) have been prepared. Both L1 and L2 coordinate to the cobalt(III) ion to give three isomers: Λ-cis-α, Δ-cis-β, trans isomers for L1 and Δ-cis-α, Δ-cis-β, trans isomers for L2. Each of the trans-dichloro complexes of the two ligands have been isomerized stereospecifically to the cis-α-dichloro complex in methanol, and each of the cis-α-dichloro complexes stereospecifically to the trans-diaqua complex in water. Both the geometrical and optical inversions took place at the same time in the observed stereospecific isomerizations. 相似文献
11.
《Tetrahedron: Asymmetry》2005,16(22):3623-3627
(2S,4R)-δ-Hydroxyleucine methyl ester, the N-demethyl analogue of an amino acid contained within the macrocycle of cyclomarin A, was successfully synthesized using Davis’ asymmetric Strecker reaction. 相似文献
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Peddikotla Prabhakar Singanaboina Rajaram Yenamandra Venkateswarlu 《Tetrahedron: Asymmetry》2009,20(15):1806-1808
An Oppolzer anti-aldol approach for the synthesis of the sex pheromone (3S,5R,6S)-3,5-dimethyl-6-isopropyl-3,4,5,6-tetrahydropyran-2-one is reported. 相似文献
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The total synthesis of (+)-(6R,2′S)-cryptocaryalactone and (−)-(6S,2′S)-epi cryptocaryalactone is reported based on stereoselective reduction of δ-hydroxy β-keto ester to install 1,3-polyol system, cis Wittig olefination, and lactonization as the key steps. The synthesis of (−)-(6S,2′S)-epi cryptocaryalactone is also reported using syn-benzylidene acetal formation and a preferential Z-Wittig olefination reaction and lactonization as the key steps. 相似文献
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The synthesis of (3S,4R,5R)-3-(2-hydroxyethyl)piperidine-3,4,5-triol 10 has been described from d-glucose. The base promoted cyclization for the construction of the piperdine framework is the key step of the synthesis. 相似文献
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Subhash P. Chavan Kishor R. Harale Nilesh B. Dumare Uttam R. Kalkote 《Tetrahedron: Asymmetry》2011,22(5):1367-590
A convenient synthesis of (2S,3S)-3-hydroxy pipecolic acid starting from inexpensive and easily available l-(+)-tartaric acid has been described. 相似文献
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Katarzyna Kiegiel Tomasz Baakier Piotr Kwiatkowski Janusz Jurczak 《Tetrahedron: Asymmetry》2004,15(24):3869-3878
The diastereoselective addition of allylsilanes and allylstannanes to N-glyoxyloyl-(2R)-bornane-10,2-sultam 1 and (1R)-8-phenylmenthyl glyoxylate 7 in the presence of Lewis acids has been studied. We obtained diastereoselectivities up to 84% and 94% for the allylation of 2 and 7, respectively. The application of the allylation products of 1 or 2 in the synthesis of 4-butanolides, for example (2S,4S)-2-hydroxy-4-hydroxymethyl-4-butanolide 13 is presented. 相似文献
17.
N. W. Fadnavis S. Kumara Vadivel Mohd Sharfuddin U. T. Bhalerao 《Tetrahedron: Asymmetry》1997,8(24):2797
Baker's yeast mediated reduction of α-azido-β-keto ester lead to reduction of the carbonyl group with high enantiospecificity and diastereoselectivity at low pH (4.0, e.e. >99%, d.e. 79%). At pH 7, although the enantioselectivity is maintained, the diastereoselectivity is lost. 相似文献
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Monica Ioana Toa Paula Veronica Podea Csaba Paizs Florin Dan Irimie 《Tetrahedron: Asymmetry》2008,19(17):2068-2071
A chemoenzymatic methodology for the synthesis of highly enantiomerically enriched (S)- and (R)-1-heteroarylethanols by enantioselective bioreduction with baker’s yeast of the corresponding 1-heteroarylethanones followed by three racemization free chemical steps including a Mitsunobu reaction was developed. 相似文献
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The Henry reaction between
-glyceraldehyde and ethyl nitroacetate allowed the practical development of a diastereoselective synthesis of 3,4,5-trihydroxy-2-nitropentanoic acid esters, which were reduced to polyoxamic acids, which were used in a new diastereoselective synthesis of 3,4-dihydroxyprolines and new enantioselective syntheses of
-threo-
-norvaline and (2S,3R,4R)-2-amino-3,4-dihydroxytetrahydrofuran-2-carboxylic acid methyl ester. 相似文献
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The (E)-α-selenylvinylstannanes react with acyl halides in presence of a catalytic amount of Pd(PPh3)4 to give the corresponding (Z)-α-selenyl-α,β-unsaturated ketones in good yield. 相似文献