The Experts below are selected from a list of 276 Experts worldwide ranked by ideXlab platform
Luigi Vaccaro - One of the best experts on this subject based on the ideXlab platform.
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Synthesis of Zirconium Phosphonate Supported L-Proline as an Effective Organocatalyst for Direct Asymmetric Aldol Addition.
ChemInform, 2014Co-Authors: Marco Angeloni, Oriana Piermatti, Ferdinando Pizzo, Luigi VaccaroAbstract:The catalyst is easily recoverable and can be used at least 6 times without any significant loss in activity.
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synthesis of zirconium phosphonate supported l proline as an effective organocatalyst for direct Asymmetric Aldol Addition
European Journal of Organic Chemistry, 2014Co-Authors: Marco Angeloni, Oriana Piermatti, Ferdinando Pizzo, Luigi VaccaroAbstract:Stable L-proline-functionalized zirconium methyl- and/or phenylphosphonates have been prepared as amorphous solids by the precipitation of (4R)-4-[(4′-phosphonobenzyl)oxy]-L-proline and methyl- and/or phenylphosphonic acid with ZrOCl2. The supported L-proline catalysts were tested in the direct Asymmetric Aldol Addition between several ketones and p-substituted benzaldehydes. High yields, diastereoselectivities (anti/syn up to 92:8) and enantiomeric excesses (up to 99 % ee) have been achieved. Moreover, an easy protocol for the efficient recovery of the catalytic system by simple centrifugation has been defined, and the effective reuse of the catalyst has been reported in the representative Aldol Addition of cyclohexanone with p-nitrobenzaldehyde. This study has shown that these L-proline immobilized catalytic systems can be used at least six times without loss of activity and with reproducible anti/syn and ee values.
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Synthesis of Zirconium Phosphonate Supported L‐Proline as an Effective Organocatalyst for Direct Asymmetric Aldol Addition
European Journal of Organic Chemistry, 2014Co-Authors: Marco Angeloni, Oriana Piermatti, Ferdinando Pizzo, Luigi VaccaroAbstract:Stable L-proline-functionalized zirconium methyl- and/or phenylphosphonates have been prepared as amorphous solids by the precipitation of (4R)-4-[(4′-phosphonobenzyl)oxy]-L-proline and methyl- and/or phenylphosphonic acid with ZrOCl2. The supported L-proline catalysts were tested in the direct Asymmetric Aldol Addition between several ketones and p-substituted benzaldehydes. High yields, diastereoselectivities (anti/syn up to 92:8) and enantiomeric excesses (up to 99 % ee) have been achieved. Moreover, an easy protocol for the efficient recovery of the catalytic system by simple centrifugation has been defined, and the effective reuse of the catalyst has been reported in the representative Aldol Addition of cyclohexanone with p-nitrobenzaldehyde. This study has shown that these L-proline immobilized catalytic systems can be used at least six times without loss of activity and with reproducible anti/syn and ee values.
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supported l proline on zirconium phosphates methyl and or phenyl phosphonates as heterogeneous organocatalysts for direct Asymmetric Aldol Addition
Journal of Catalysis, 2011Co-Authors: Salvatore Calogero, Daniela Lanari, Mara Orrù, Oriana Piermatti, Ferdinando Pizzo, Luigi VaccaroAbstract:Zirconium phosphates methyl and/or phenyl phosphonates-supported l-proline have been prepared as amorphous solids by precipitation of (4R)-4-(phosphonooxy)-l-proline, methyl and/or phenyl phosphonic acid with ZrOCl2. The supported l-proline catalysts were tested on the direct Asymmetric Aldol Addition of cyclohexanone to p-nitrobenzaldehyde in DMF/H2O (9:1) and in sole water. The hydrophobic groups on solid surface favor reagents’ diffusion toward proline chiral moiety increasing the catalytic activity of supported l-proline. High diastereoselectivity (anti/syn up to 94:6) and high enantiomeric excess up to 97% have been obtained.
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Supported l-proline on zirconium phosphates methyl and/or phenyl phosphonates as heterogeneous organocatalysts for direct Asymmetric Aldol Addition
Journal of Catalysis, 2011Co-Authors: Salvatore Calogero, Daniela Lanari, Mara Orrù, Oriana Piermatti, Ferdinando Pizzo, Luigi VaccaroAbstract:Zirconium phosphates methyl and/or phenyl phosphonates-supported l-proline have been prepared as amorphous solids by precipitation of (4R)-4-(phosphonooxy)-l-proline, methyl and/or phenyl phosphonic acid with ZrOCl2. The supported l-proline catalysts were tested on the direct Asymmetric Aldol Addition of cyclohexanone to p-nitrobenzaldehyde in DMF/H2O (9:1) and in sole water. The hydrophobic groups on solid surface favor reagents’ diffusion toward proline chiral moiety increasing the catalytic activity of supported l-proline. High diastereoselectivity (anti/syn up to 94:6) and high enantiomeric excess up to 97% have been obtained.
James W. Leahy - One of the best experts on this subject based on the ideXlab platform.
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rhizoxin synthetic studies 1 synthesis of the right hand c 1 to c 9 portion via a pinwheel approach
Tetrahedron Letters, 1995Co-Authors: Jennifer A. Lafontaine, James W. LeahyAbstract:Abstract A concise synthetic approach to the C(1) - C(9) fragment of the antitumor macrolide rhizoxin via a three-fold pseudosymmetric intermediate is described. The preparation (from readily available γ-butyrolactone) includes both an Asymmetric allylation and an Asymmetric Aldol Addition. The pseudosymmetry proved useful in the realization of the target ( 4 ).
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Rhizoxin synthetic studies. 1. Synthesis of the right hand [C(1) to C(9)]portion via a “pinwheel” approach
Tetrahedron Letters, 1995Co-Authors: Jennifer A. Lafontaine, James W. LeahyAbstract:Abstract A concise synthetic approach to the C(1) - C(9) fragment of the antitumor macrolide rhizoxin via a three-fold pseudosymmetric intermediate is described. The preparation (from readily available γ-butyrolactone) includes both an Asymmetric allylation and an Asymmetric Aldol Addition. The pseudosymmetry proved useful in the realization of the target ( 4 ).
Oriana Piermatti - One of the best experts on this subject based on the ideXlab platform.
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Synthesis of Zirconium Phosphonate Supported L-Proline as an Effective Organocatalyst for Direct Asymmetric Aldol Addition.
ChemInform, 2014Co-Authors: Marco Angeloni, Oriana Piermatti, Ferdinando Pizzo, Luigi VaccaroAbstract:The catalyst is easily recoverable and can be used at least 6 times without any significant loss in activity.
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synthesis of zirconium phosphonate supported l proline as an effective organocatalyst for direct Asymmetric Aldol Addition
European Journal of Organic Chemistry, 2014Co-Authors: Marco Angeloni, Oriana Piermatti, Ferdinando Pizzo, Luigi VaccaroAbstract:Stable L-proline-functionalized zirconium methyl- and/or phenylphosphonates have been prepared as amorphous solids by the precipitation of (4R)-4-[(4′-phosphonobenzyl)oxy]-L-proline and methyl- and/or phenylphosphonic acid with ZrOCl2. The supported L-proline catalysts were tested in the direct Asymmetric Aldol Addition between several ketones and p-substituted benzaldehydes. High yields, diastereoselectivities (anti/syn up to 92:8) and enantiomeric excesses (up to 99 % ee) have been achieved. Moreover, an easy protocol for the efficient recovery of the catalytic system by simple centrifugation has been defined, and the effective reuse of the catalyst has been reported in the representative Aldol Addition of cyclohexanone with p-nitrobenzaldehyde. This study has shown that these L-proline immobilized catalytic systems can be used at least six times without loss of activity and with reproducible anti/syn and ee values.
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Synthesis of Zirconium Phosphonate Supported L‐Proline as an Effective Organocatalyst for Direct Asymmetric Aldol Addition
European Journal of Organic Chemistry, 2014Co-Authors: Marco Angeloni, Oriana Piermatti, Ferdinando Pizzo, Luigi VaccaroAbstract:Stable L-proline-functionalized zirconium methyl- and/or phenylphosphonates have been prepared as amorphous solids by the precipitation of (4R)-4-[(4′-phosphonobenzyl)oxy]-L-proline and methyl- and/or phenylphosphonic acid with ZrOCl2. The supported L-proline catalysts were tested in the direct Asymmetric Aldol Addition between several ketones and p-substituted benzaldehydes. High yields, diastereoselectivities (anti/syn up to 92:8) and enantiomeric excesses (up to 99 % ee) have been achieved. Moreover, an easy protocol for the efficient recovery of the catalytic system by simple centrifugation has been defined, and the effective reuse of the catalyst has been reported in the representative Aldol Addition of cyclohexanone with p-nitrobenzaldehyde. This study has shown that these L-proline immobilized catalytic systems can be used at least six times without loss of activity and with reproducible anti/syn and ee values.
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supported l proline on zirconium phosphates methyl and or phenyl phosphonates as heterogeneous organocatalysts for direct Asymmetric Aldol Addition
Journal of Catalysis, 2011Co-Authors: Salvatore Calogero, Daniela Lanari, Mara Orrù, Oriana Piermatti, Ferdinando Pizzo, Luigi VaccaroAbstract:Zirconium phosphates methyl and/or phenyl phosphonates-supported l-proline have been prepared as amorphous solids by precipitation of (4R)-4-(phosphonooxy)-l-proline, methyl and/or phenyl phosphonic acid with ZrOCl2. The supported l-proline catalysts were tested on the direct Asymmetric Aldol Addition of cyclohexanone to p-nitrobenzaldehyde in DMF/H2O (9:1) and in sole water. The hydrophobic groups on solid surface favor reagents’ diffusion toward proline chiral moiety increasing the catalytic activity of supported l-proline. High diastereoselectivity (anti/syn up to 94:6) and high enantiomeric excess up to 97% have been obtained.
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Supported l-proline on zirconium phosphates methyl and/or phenyl phosphonates as heterogeneous organocatalysts for direct Asymmetric Aldol Addition
Journal of Catalysis, 2011Co-Authors: Salvatore Calogero, Daniela Lanari, Mara Orrù, Oriana Piermatti, Ferdinando Pizzo, Luigi VaccaroAbstract:Zirconium phosphates methyl and/or phenyl phosphonates-supported l-proline have been prepared as amorphous solids by precipitation of (4R)-4-(phosphonooxy)-l-proline, methyl and/or phenyl phosphonic acid with ZrOCl2. The supported l-proline catalysts were tested on the direct Asymmetric Aldol Addition of cyclohexanone to p-nitrobenzaldehyde in DMF/H2O (9:1) and in sole water. The hydrophobic groups on solid surface favor reagents’ diffusion toward proline chiral moiety increasing the catalytic activity of supported l-proline. High diastereoselectivity (anti/syn up to 94:6) and high enantiomeric excess up to 97% have been obtained.
Ferdinando Pizzo - One of the best experts on this subject based on the ideXlab platform.
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Synthesis of Zirconium Phosphonate Supported L-Proline as an Effective Organocatalyst for Direct Asymmetric Aldol Addition.
ChemInform, 2014Co-Authors: Marco Angeloni, Oriana Piermatti, Ferdinando Pizzo, Luigi VaccaroAbstract:The catalyst is easily recoverable and can be used at least 6 times without any significant loss in activity.
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synthesis of zirconium phosphonate supported l proline as an effective organocatalyst for direct Asymmetric Aldol Addition
European Journal of Organic Chemistry, 2014Co-Authors: Marco Angeloni, Oriana Piermatti, Ferdinando Pizzo, Luigi VaccaroAbstract:Stable L-proline-functionalized zirconium methyl- and/or phenylphosphonates have been prepared as amorphous solids by the precipitation of (4R)-4-[(4′-phosphonobenzyl)oxy]-L-proline and methyl- and/or phenylphosphonic acid with ZrOCl2. The supported L-proline catalysts were tested in the direct Asymmetric Aldol Addition between several ketones and p-substituted benzaldehydes. High yields, diastereoselectivities (anti/syn up to 92:8) and enantiomeric excesses (up to 99 % ee) have been achieved. Moreover, an easy protocol for the efficient recovery of the catalytic system by simple centrifugation has been defined, and the effective reuse of the catalyst has been reported in the representative Aldol Addition of cyclohexanone with p-nitrobenzaldehyde. This study has shown that these L-proline immobilized catalytic systems can be used at least six times without loss of activity and with reproducible anti/syn and ee values.
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Synthesis of Zirconium Phosphonate Supported L‐Proline as an Effective Organocatalyst for Direct Asymmetric Aldol Addition
European Journal of Organic Chemistry, 2014Co-Authors: Marco Angeloni, Oriana Piermatti, Ferdinando Pizzo, Luigi VaccaroAbstract:Stable L-proline-functionalized zirconium methyl- and/or phenylphosphonates have been prepared as amorphous solids by the precipitation of (4R)-4-[(4′-phosphonobenzyl)oxy]-L-proline and methyl- and/or phenylphosphonic acid with ZrOCl2. The supported L-proline catalysts were tested in the direct Asymmetric Aldol Addition between several ketones and p-substituted benzaldehydes. High yields, diastereoselectivities (anti/syn up to 92:8) and enantiomeric excesses (up to 99 % ee) have been achieved. Moreover, an easy protocol for the efficient recovery of the catalytic system by simple centrifugation has been defined, and the effective reuse of the catalyst has been reported in the representative Aldol Addition of cyclohexanone with p-nitrobenzaldehyde. This study has shown that these L-proline immobilized catalytic systems can be used at least six times without loss of activity and with reproducible anti/syn and ee values.
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supported l proline on zirconium phosphates methyl and or phenyl phosphonates as heterogeneous organocatalysts for direct Asymmetric Aldol Addition
Journal of Catalysis, 2011Co-Authors: Salvatore Calogero, Daniela Lanari, Mara Orrù, Oriana Piermatti, Ferdinando Pizzo, Luigi VaccaroAbstract:Zirconium phosphates methyl and/or phenyl phosphonates-supported l-proline have been prepared as amorphous solids by precipitation of (4R)-4-(phosphonooxy)-l-proline, methyl and/or phenyl phosphonic acid with ZrOCl2. The supported l-proline catalysts were tested on the direct Asymmetric Aldol Addition of cyclohexanone to p-nitrobenzaldehyde in DMF/H2O (9:1) and in sole water. The hydrophobic groups on solid surface favor reagents’ diffusion toward proline chiral moiety increasing the catalytic activity of supported l-proline. High diastereoselectivity (anti/syn up to 94:6) and high enantiomeric excess up to 97% have been obtained.
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Supported l-proline on zirconium phosphates methyl and/or phenyl phosphonates as heterogeneous organocatalysts for direct Asymmetric Aldol Addition
Journal of Catalysis, 2011Co-Authors: Salvatore Calogero, Daniela Lanari, Mara Orrù, Oriana Piermatti, Ferdinando Pizzo, Luigi VaccaroAbstract:Zirconium phosphates methyl and/or phenyl phosphonates-supported l-proline have been prepared as amorphous solids by precipitation of (4R)-4-(phosphonooxy)-l-proline, methyl and/or phenyl phosphonic acid with ZrOCl2. The supported l-proline catalysts were tested on the direct Asymmetric Aldol Addition of cyclohexanone to p-nitrobenzaldehyde in DMF/H2O (9:1) and in sole water. The hydrophobic groups on solid surface favor reagents’ diffusion toward proline chiral moiety increasing the catalytic activity of supported l-proline. High diastereoselectivity (anti/syn up to 94:6) and high enantiomeric excess up to 97% have been obtained.
Allison L. Choy - One of the best experts on this subject based on the ideXlab platform.
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An Asymmetric Aldol—Ring‐Closing Metathesis Strategy for the Enantioselective Construction of Oxygen Heterocycles: An Efficient Approach to the Enantioselective Synthesis of (+)‐Laurencin.
ChemInform, 2010Co-Authors: Michael T. Crimmins, Allison L. ChoyAbstract:A strategy is described for the enantioselective construction of medium-ring cyclic ethers by merging the Asymmetric Aldol Addition of glycolates with a ring-closing metathesis reaction. Cyclic ethers of seven-, eight-, and nine-membered rings are readily available through a ring-closing metathesis without cyclic conformational constraints, by exploiting the acyclic conformational bias of the gauche effect. A short formal synthesis of the eight-membered ether (+)-laurencin, a red algae metabolite, has been accomplished utilizing the Aldol−metathesis combination.
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An Efficient, General Asymmetric Synthesis of Carbocyclic Nucleosides: Application of an Asymmetric Aldol/Ring‐Closing Metathesis Strategy.
ChemInform, 2001Co-Authors: Michael T. Crimmins, Bryan W. King, William J. Zuercher, Allison L. ChoyAbstract:A general and efficient synthesis of carbocyclic and hexenopyranosyl nucleosides has been developed. The strategy combines three key transformations: an Asymmetric Aldol Addition to establish the relative and absolute configuration of the pseudosugar, a ring-closing metathesis to construct the pseudosugar ring, and a Trost-type palladium(0)-mediated substitution to assemble the pseudosugar and the aromatic base. Carbovir, abacavir, and their 2'-methyl derivatives as well as hexenopyranosyl nucleoside analogues have been prepared by this sequence.
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An efficient, general Asymmetric synthesis of carbocyclic nucleosides: Application of an Asymmetric Aldol/ring-closing metathesis strategy
The Journal of organic chemistry, 2000Co-Authors: Michael T. Crimmins, Bryan W. King, William J. Zuercher, Allison L. ChoyAbstract:A general and efficient synthesis of carbocyclic and hexenopyranosyl nucleosides has been developed. The strategy combines three key transformations: an Asymmetric Aldol Addition to establish the relative and absolute configuration of the pseudosugar, a ring-closing metathesis to construct the pseudosugar ring, and a Trost-type palladium(0)-mediated substitution to assemble the pseudosugar and the aromatic base. Carbovir, abacavir, and their 2'-methyl derivatives as well as hexenopyranosyl nucleoside analogues have been prepared by this sequence.
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an Asymmetric Aldol ring closing metathesis strategy for the enantioselective construction of oxygen heterocycles an efficient approach to the enantioselective synthesis of laurencin
Journal of the American Chemical Society, 1999Co-Authors: Michael T. Crimmins, Allison L. ChoyAbstract:A strategy is described for the enantioselective construction of medium-ring cyclic ethers by merging the Asymmetric Aldol Addition of glycolates with a ring-closing metathesis reaction. Cyclic ethers of seven-, eight-, and nine-membered rings are readily available through a ring-closing metathesis without cyclic conformational constraints, by exploiting the acyclic conformational bias of the gauche effect. A short formal synthesis of the eight-membered ether (+)-laurencin, a red algae metabolite, has been accomplished utilizing the Aldol−metathesis combination.
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An Asymmetric Aldol−Ring-Closing Metathesis Strategy for the Enantioselective Construction of Oxygen Heterocycles: An Efficient Approach to the Enantioselective Synthesis of (+)-Laurencin
Journal of the American Chemical Society, 1999Co-Authors: Michael T. Crimmins, Allison L. ChoyAbstract:A strategy is described for the enantioselective construction of medium-ring cyclic ethers by merging the Asymmetric Aldol Addition of glycolates with a ring-closing metathesis reaction. Cyclic ethers of seven-, eight-, and nine-membered rings are readily available through a ring-closing metathesis without cyclic conformational constraints, by exploiting the acyclic conformational bias of the gauche effect. A short formal synthesis of the eight-membered ether (+)-laurencin, a red algae metabolite, has been accomplished utilizing the Aldol−metathesis combination.
