The Experts below are selected from a list of 144 Experts worldwide ranked by ideXlab platform
Stephen F. Martin - One of the best experts on this subject based on the ideXlab platform.
-
Enantioselective Halolactonization Reactions using BINOL-derived Bifunctional Catalysts: Methodology, Diversification, and Applications
Journal of Organic Chemistry, 2018Co-Authors: Daniel W. Klosowski, J. Caleb Hethcox, Daniel H. Paull, Christopher R. Shugrue, Andrew D. Pansick, James R. Donald, Chao Fang, Stephen F. MartinAbstract:A general protocol is described for inducing enantioselective Halolactonizations of unsaturated carboxylic acids using novel bifunctional organic catalysts derived from a chiral binaphthalene scaffold. Bromo- and iodolactonization reactions of diversely substituted, unsaturated carboxylic acids proceed with high degrees of enantioselectivity, regioselectivity, and diastereoselectivity. Notably, these BINOL-derived catalysts are the first to induce the bromo- and iodolactonizations of 5-alkyl-4(Z)-olefinic acids via 5-exo mode cyclizations to give lactones in which new carbon–halogen bonds are created at a stereogenic center with high diastereo- and enantioselectivities. Iodolactonizations of 6-substituted-5(Z)-olefinic acids also occur via 6-exo cyclizations to provide δ-lactones with excellent enantioselectivities. Several notable applications of this Halolactonization methodology were developed for desymmetrization, kinetic resolution, and epoxidation of Z-alkenes. The utility of these reactions is demo...
-
synthesis of disparlure via enantioselective iodolactonization
Organic Letters, 2018Co-Authors: Daniel W. Klosowski, Stephen F. MartinAbstract:The BINOL-amidine organic catalyst 1 was previously shown to promote highly efficient enantioselective Halolactonization reactions of olefinic acids. As part of these studies, it was discovered that the enantioenriched iodolactones could be easily converted into enantioenriched cis-1,2-disubstituted epoxides. This Halolactonization-epoxidation sequence was applied to the synthesis of (+)-disparlure, which resulted in the shortest catalytic enantioselective synthesis to date, requiring only five steps and proceeding in 33% yield.
-
Synthesis of (+)-Disparlure via Enantioselective Iodolactonization.
Organic Letters, 2018Co-Authors: Daniel W. Klosowski, Stephen F. MartinAbstract:The BINOL-amidine organic catalyst 1 was previously shown to promote highly efficient enantioselective Halolactonization reactions of olefinic acids. As part of these studies, it was discovered that the enantioenriched iodolactones could be easily converted into enantioenriched cis-1,2-disubstituted epoxides. This Halolactonization-epoxidation sequence was applied to the synthesis of (+)-disparlure, which resulted in the shortest catalytic enantioselective synthesis to date, requiring only five steps and proceeding in 33% yield.
-
Enantioselective Halolactonization Reactions using BINOL-Derived Bifunctional Catalysts: Methodology, Diversification, and Applications
2018Co-Authors: Daniel W. Klosowski, Daniel H. Paull, Christopher R. Shugrue, Andrew D. Pansick, James R. Donald, Chao Fang, Caleb J. Hethcox, Stephen F. MartinAbstract:A general protocol is described for inducing enantioselective Halolactonizations of unsaturated carboxylic acids using novel bifunctional organic catalysts derived from a chiral binaphthalene scaffold. Bromo- and iodolactonization reactions of diversely substituted, unsaturated carboxylic acids proceed with high degrees of enantioselectivity, regioselectivity, and diastereoselectivity. Notably, these BINOL-derived catalysts are the first to induce the bromo- and iodolactonizations of 5-alkyl-4(Z)-olefinic acids via 5-exo mode cyclizations to give lactones in which new carbon–halogen bonds are created at a stereogenic center with high diastereo- and enantioselectivities. Iodolactonizations of 6-substituted-5(Z)-olefinic acids also occur via 6-exo cyclizations to provide δ-lactones with excellent enantioselectivities. Several notable applications of this Halolactonization methodology were developed for desymmetrization, kinetic resolution, and epoxidation of Z-alkenes. The utility of these reactions is demonstrated by their application to a synthesis of precursors of the F-ring subunit of kibdelone C and to the shortest catalytic, enantioselective synthesis of (+)-disparlure reported to date
Daniel W. Klosowski - One of the best experts on this subject based on the ideXlab platform.
-
Enantioselective Halolactonization Reactions using BINOL-derived Bifunctional Catalysts: Methodology, Diversification, and Applications
Journal of Organic Chemistry, 2018Co-Authors: Daniel W. Klosowski, J. Caleb Hethcox, Daniel H. Paull, Christopher R. Shugrue, Andrew D. Pansick, James R. Donald, Chao Fang, Stephen F. MartinAbstract:A general protocol is described for inducing enantioselective Halolactonizations of unsaturated carboxylic acids using novel bifunctional organic catalysts derived from a chiral binaphthalene scaffold. Bromo- and iodolactonization reactions of diversely substituted, unsaturated carboxylic acids proceed with high degrees of enantioselectivity, regioselectivity, and diastereoselectivity. Notably, these BINOL-derived catalysts are the first to induce the bromo- and iodolactonizations of 5-alkyl-4(Z)-olefinic acids via 5-exo mode cyclizations to give lactones in which new carbon–halogen bonds are created at a stereogenic center with high diastereo- and enantioselectivities. Iodolactonizations of 6-substituted-5(Z)-olefinic acids also occur via 6-exo cyclizations to provide δ-lactones with excellent enantioselectivities. Several notable applications of this Halolactonization methodology were developed for desymmetrization, kinetic resolution, and epoxidation of Z-alkenes. The utility of these reactions is demo...
-
synthesis of disparlure via enantioselective iodolactonization
Organic Letters, 2018Co-Authors: Daniel W. Klosowski, Stephen F. MartinAbstract:The BINOL-amidine organic catalyst 1 was previously shown to promote highly efficient enantioselective Halolactonization reactions of olefinic acids. As part of these studies, it was discovered that the enantioenriched iodolactones could be easily converted into enantioenriched cis-1,2-disubstituted epoxides. This Halolactonization-epoxidation sequence was applied to the synthesis of (+)-disparlure, which resulted in the shortest catalytic enantioselective synthesis to date, requiring only five steps and proceeding in 33% yield.
-
Synthesis of (+)-Disparlure via Enantioselective Iodolactonization.
Organic Letters, 2018Co-Authors: Daniel W. Klosowski, Stephen F. MartinAbstract:The BINOL-amidine organic catalyst 1 was previously shown to promote highly efficient enantioselective Halolactonization reactions of olefinic acids. As part of these studies, it was discovered that the enantioenriched iodolactones could be easily converted into enantioenriched cis-1,2-disubstituted epoxides. This Halolactonization-epoxidation sequence was applied to the synthesis of (+)-disparlure, which resulted in the shortest catalytic enantioselective synthesis to date, requiring only five steps and proceeding in 33% yield.
-
Enantioselective Halolactonization Reactions using BINOL-Derived Bifunctional Catalysts: Methodology, Diversification, and Applications
2018Co-Authors: Daniel W. Klosowski, Daniel H. Paull, Christopher R. Shugrue, Andrew D. Pansick, James R. Donald, Chao Fang, Caleb J. Hethcox, Stephen F. MartinAbstract:A general protocol is described for inducing enantioselective Halolactonizations of unsaturated carboxylic acids using novel bifunctional organic catalysts derived from a chiral binaphthalene scaffold. Bromo- and iodolactonization reactions of diversely substituted, unsaturated carboxylic acids proceed with high degrees of enantioselectivity, regioselectivity, and diastereoselectivity. Notably, these BINOL-derived catalysts are the first to induce the bromo- and iodolactonizations of 5-alkyl-4(Z)-olefinic acids via 5-exo mode cyclizations to give lactones in which new carbon–halogen bonds are created at a stereogenic center with high diastereo- and enantioselectivities. Iodolactonizations of 6-substituted-5(Z)-olefinic acids also occur via 6-exo cyclizations to provide δ-lactones with excellent enantioselectivities. Several notable applications of this Halolactonization methodology were developed for desymmetrization, kinetic resolution, and epoxidation of Z-alkenes. The utility of these reactions is demonstrated by their application to a synthesis of precursors of the F-ring subunit of kibdelone C and to the shortest catalytic, enantioselective synthesis of (+)-disparlure reported to date
Trond Vidar Hansen - One of the best experts on this subject based on the ideXlab platform.
-
catalytic enantioselective iodolactonization reactions
Organic and Biomolecular Chemistry, 2019Co-Authors: Renate Kristianslund, Jorn Eivind Tungen, Trond Vidar HansenAbstract:The Halolactonization reaction is a useful chemical transformation for the construction of lactones from γ- or δ-substituted alkenoic carboxylic acids or carboxylic esters. Traditionally, the stereoselectivity of these reactions has been controlled by the substrates or the reagents. The substrate-controlled method has been extensively studied and applied in the synthesis of many natural products. However, catalytic, enantioselective iodolactonizations of γ- or δ-substituted alkenoic carboxylic acids have only recently been developed. This review article highlights the advances that have emerged over the last decade.
-
asymmetric iodolactonization an evolutionary account
European Journal of Organic Chemistry, 2014Co-Authors: Jens M J Nolsoe, Trond Vidar HansenAbstract:The diversity entailed by Halolactonization makes it a fundamental transformation, enabling the synthetic organic chemist to build up molecular complexity in a way that relates structural elements in a predictable manner. Due to practical aspects and the subsequent flexible manipulation of the installed halogen handle, iodolactonization takes precedence over the other variants. The asymmetry that can be conferred on the products by iodine-induced cyclization has been the subject of various approaches. For a long time stereoselectivity has been achieved by substrate-controlled reactions. However, lately, the reagent-controlled counterpart has surfaced as an alternative based on the action of a catalyst. Despite the fact that the current progress in catalytic asymmetric iodolactonization has happened only in the space of the last three years, a number of conceptually different approaches have already been applied to advance beyond the substrate-controlled reaction. Herein we describe the various strategies, which have propelled the development of asymmetric iodolactonization to its current state, putting an emphasis on catalysis.
Eric Deniau - One of the best experts on this subject based on the ideXlab platform.
-
total synthesis of herbaric acid through organocatalyzed asymmetric Halolactonization of acrylate type benzoic acids
Synlett, 2016Co-Authors: Fabien Gelat, Stephane Lebrun, Natacha Henry, Francine Agbossouniedercorn, Christophe Michon, Eric DeniauAbstract:The total synthesis of (–)-herbaric acid has been achieved through the stereoselective synthesis of 3-substituted isobenzofuranones with a new organocatalytic route. When combined with a catalytic amount of benzoic acid, quinidine thiocarbamate based bifunctional catalysts have demonstrated their efficiency for the diastereoselective Halolactonization reaction of acrylate-type benzoic acids bearing a chiral alkoxycarbonyl group on the carbon–carbon double bond. High diastereomeric excesses were obtained thanks to a positive match effect between the (+)-menthyl ester group and the chiral organocatalyst.
John O Trent - One of the best experts on this subject based on the ideXlab platform.
-
halogenation of keto acid phosphoranes synthesis of halo enol lactones and haloallenes
Journal of Organic Chemistry, 1993Co-Authors: Andrew D Abell, Deborah A Hoult, Kathy M Morris, Jane M Taylor, John O TrentAbstract:Halolactonization of the keto acid phosphoranes 6a-f, 40, and 41 takes place with either Br 2 or SO 2 Cl 2 and Et 3 N to give the E- and Z-halo enol lactones 10-15, 42, and 43 in good yields. The cyclization proceeds via a halo phosphonium salt, e.g. 19. Halo phosphonium salts yield a halo allene when cyclization is not favoured as in the formation of the bromoallenes 24 and 37. The configuration of the halo enol lactones was determined by 1 H and 13 C NMR spectroscopy and via single-crystal X-ray determinations on 11a, 14c, and 42b. The barrier to interconversion of the biphenyl conformations of the bromo enol lactaones 42b and 43b was determined by 1 H NMR spectroscopy at elevated temperatures
