The Experts below are selected from a list of 1329 Experts worldwide ranked by ideXlab platform
Venkateswara B Rao - One of the best experts on this subject based on the ideXlab platform.
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a common and stereoselective strategy for the synthesis of n o o o tetra acetyl d ribo 2s 3s 4r phytosphingosine and 2 epi jaspine b
Tetrahedron Letters, 2011Co-Authors: Srinivas G Rao, Venkateswara B RaoAbstract:Abstract A common and stereoselective strategy for the synthesis of N , O , O , O -tetra-acetyl d - ribo -(2 S ,3 S ,4 R )-phytosphingosine and 2- epi -jaspine B was achieved by using Grignard addition on N -benzyl sugar lactamine and Wittig Olefination as key steps.
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a chiron approach to 1r 2r 5s 7s 2 hydroxy exo brevicomin a component of the volatiles produced by the male mountain pine beetle dendroctonus ponderosae
Tetrahedron-asymmetry, 2005Co-Authors: Naveen D Kumar, Venkateswara B Rao, G S RamanjaneyuluAbstract:Abstract A chiron approach for the synthesis of (1 R ,2 R ,5 S ,7 S )-2-hydroxy- exo -brevicomin 1 , a component of the volatiles obtained from male mountain pine beetles, Dendroctonus ponderosae has been achieved. Our synthesis started with commercially available d -ribose and involves a Wittig Olefination, an acid catalyzed one pot hydrogenation and the internal acetalization as key steps.
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a chiron approach to 1r 2r 5s 7r 2 hydroxy exo brevicomin a component of the volatiles produced by the male mountain pine beetle dendroctonus ponderosae
Tetrahedron Letters, 2004Co-Authors: Naveen D Kumar, Venkateswara B RaoAbstract:Abstract A chiron approach to a synthesis of (1 R ,2 R ,5 S ,7 R )-2-hydroxy- exo -brevicomin 1 , a component of the volatiles obtained from male mountain pine beetles, Dendroctonus ponderosae has been achieved. Our synthesis started with commercially available d -mannitol and involved Wittig Olefination, acid catalysed one-pot hydrogenation and internal acetalization as key steps.
Naveen D Kumar - One of the best experts on this subject based on the ideXlab platform.
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a chiron approach to 1r 2r 5s 7s 2 hydroxy exo brevicomin a component of the volatiles produced by the male mountain pine beetle dendroctonus ponderosae
Tetrahedron-asymmetry, 2005Co-Authors: Naveen D Kumar, Venkateswara B Rao, G S RamanjaneyuluAbstract:Abstract A chiron approach for the synthesis of (1 R ,2 R ,5 S ,7 S )-2-hydroxy- exo -brevicomin 1 , a component of the volatiles obtained from male mountain pine beetles, Dendroctonus ponderosae has been achieved. Our synthesis started with commercially available d -ribose and involves a Wittig Olefination, an acid catalyzed one pot hydrogenation and the internal acetalization as key steps.
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a chiron approach to 1r 2r 5s 7r 2 hydroxy exo brevicomin a component of the volatiles produced by the male mountain pine beetle dendroctonus ponderosae
Tetrahedron Letters, 2004Co-Authors: Naveen D Kumar, Venkateswara B RaoAbstract:Abstract A chiron approach to a synthesis of (1 R ,2 R ,5 S ,7 R )-2-hydroxy- exo -brevicomin 1 , a component of the volatiles obtained from male mountain pine beetles, Dendroctonus ponderosae has been achieved. Our synthesis started with commercially available d -mannitol and involved Wittig Olefination, acid catalysed one-pot hydrogenation and internal acetalization as key steps.
G S Ramanjaneyulu - One of the best experts on this subject based on the ideXlab platform.
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a chiron approach to 1r 2r 5s 7s 2 hydroxy exo brevicomin a component of the volatiles produced by the male mountain pine beetle dendroctonus ponderosae
Tetrahedron-asymmetry, 2005Co-Authors: Naveen D Kumar, Venkateswara B Rao, G S RamanjaneyuluAbstract:Abstract A chiron approach for the synthesis of (1 R ,2 R ,5 S ,7 S )-2-hydroxy- exo -brevicomin 1 , a component of the volatiles obtained from male mountain pine beetles, Dendroctonus ponderosae has been achieved. Our synthesis started with commercially available d -ribose and involves a Wittig Olefination, an acid catalyzed one pot hydrogenation and the internal acetalization as key steps.
Bernd Schmidt - One of the best experts on this subject based on the ideXlab platform.
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prenylcoumarins in one or two steps by a microwave promoted tandem claisen rearrangement Wittig Olefination cyclization sequence
Journal of Organic Chemistry, 2018Co-Authors: Christiane Schultze, Bernd SchmidtAbstract:The one-pot synthesis of 8-prenylcoumarins from 1,1-dimethylallylated salicylaldehydes and the stabilized ylide [(ethoxycarbonyl)methylene]triphenylphosphorane under microwave conditions was found to have a limited scope. The sequence suffers from a difficult and sometimes low-yielding synthesis of the precursors and from a competing deprenylation upon microwave irradiation. This side reaction occurs in particular with electron rich arenes with two or more alkoxy groups at adjacent positions, a prominent substitution pattern in naturally occurring 8-prenylcoumarins. Both limitations of this one-step sequence were overcome by a two-step synthesis consisting of a microwave-promoted tandem allyl ether Claisen rearrangement/Wittig Olefination and a subsequent olefin cross metathesis with 2-methyl-2-butene. The cross metathesis step proceeds with a high selectivity and yields exclusively the desired prenyl, rather than the alternative crotyl substituent. Several naturally occurring 8-prenylcoumarins that were previously inaccessible have been synthesized in good overall yields along this route.
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Prenylcoumarins in One or Two Steps by a Microwave-Promoted Tandem Claisen Rearrangement/Wittig Olefination/Cyclization Sequence
2018Co-Authors: Christiane Schultze, Bernd SchmidtAbstract:The one-pot synthesis of 8-prenylcoumarins from 1,1-dimethylallylated salicylaldehydes and the stabilized ylide [(ethoxycarbonyl)methylene]triphenylphosphorane under microwave conditions was found to have a limited scope. The sequence suffers from a difficult and sometimes low-yielding synthesis of the precursors and from a competing deprenylation upon microwave irradiation. This side reaction occurs in particular with electron rich arenes with two or more alkoxy groups at adjacent positions, a prominent substitution pattern in naturally occurring 8-prenylcoumarins. Both limitations of this one-step sequence were overcome by a two-step synthesis consisting of a microwave-promoted tandem allyl ether Claisen rearrangement/Wittig Olefination and a subsequent olefin cross metathesis with 2-methyl-2-butene. The cross metathesis step proceeds with a high selectivity and yields exclusively the desired prenyl, rather than the alternative crotyl substituent. Several naturally occurring 8-prenylcoumarins that were previously inaccessible have been synthesized in good overall yields along this route
Wenhua Huang - One of the best experts on this subject based on the ideXlab platform.
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cyclic α alkoxyphosphonium salts from 2 diphenylphosphino phenyl methanol and aldehydes and their application in synthesis of vinyl ethers and ketones via Wittig Olefination
Journal of Organic Chemistry, 2015Co-Authors: Wenhua Huang, Hongying RongAbstract:Cyclic α-alkoxyphosphonium salts have been synthesized from (2-(diphenylphosphino)phenyl)methanol and aldehydes in 36-89% yields. These phosphonium salts are bench-stable solids and undergo Wittig Olefination with aldehydes under basic conditions (K2CO3 or t-BuOK) to form benzylic vinyl ethers, which are readily hydrolyzed to 1,2-disubstituted ethanones under acidic conditions. The formation mechanism of these phosphonium salts via hemiacetal is also proposed.
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One-Pot Synthesis of Cyclopropane Derivatives with a cis:trans Stereo-Selectivity by Wittig Olefination-Sulfur Ylide Cyclopropanation Sequence.
ChemInform, 2013Co-Authors: Wenhua Huang, Lai‐ling WangAbstract:An efficient synthesis of cyclopropane derivatives is developed using a tandem Wittig Olefination/sulfur ylide cyclopropanation reaction sequence.
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One-pot Synthesis of Cyclopropane Derivatives with a Cis:Trans Stereoselectivity by Wittig Olefination-Sulfur Ylide Cyclopropanation Sequence:
Journal of Chemical Research, 2013Co-Authors: Wenhua Huang, Lai-ling WangAbstract:Cyclopropane derivatives were synthesised in one pot from aromatic aldehydes, phenacyltriphenylphosphonium bromide, and S-phenacylthiolanium bromide by a Wittig Olefination-sulfur ylide cyclopropan...
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one pot synthesis of 2 4 5 trisubstituted oxazoles from n acyl amino acids by a combination of cyclodehydration with n n diisopropylcarbodiimide and Wittig Olefination
Tetrahedron, 2012Co-Authors: Wenhua Huang, Guangping Dong, Zumureti MijitiAbstract:Abstract By a combination of cyclodehydration of N-acyl amino acids with N,N′-diisopropylcarbodiimide (DIC) and non-classical Wittig Olefination of the resultant 5(4H)-oxazolones with Ph3P CHCN and Ph3P CHCOOEt, 5-oxazoleacetonitriles and 5-oxazoleacetates were synthesized in one-pot in 41–85% and 57–70% yields, respectively.
