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Papers by Sirinporn Thamapipol

Research paper thumbnail of Intramolecular Diels–Alder reactions using chiral ruthenium Lewis acids and application in the total synthesis of ent-ledol

Organic & Biomolecular Chemistry, 2011

One-point binding chiral ruthenium Lewis acids incorporating the C(2)-symmetric electron-poor bid... more One-point binding chiral ruthenium Lewis acids incorporating the C(2)-symmetric electron-poor bidentate phosphinite ligand BIPHOP-F and a Cp or an indenyl 'roof' can efficiently catalyze asymmetric intramolecular Diels-Alder reactions of trienes to form bicyclic adducts with good to excellent asymmetric induction. This reaction forms the key step in a total synthesis of ent-ledol in 96% ee. The synthesis also helps to clarify the stereochemical assignment of ledol and inconsistencies in the measured optical rotation.

Research paper thumbnail of Morita−Baylis−Hillman Reaction of Masked 5-Alkylidene-2-cyclopentenones:  General Entry to 5-Alkylidene-2-(hydroxyalkyl)- 2-cyclopentenones

The Journal of Organic Chemistry, 2007

Research paper thumbnail of Reactions of Trienals Catalyzed by Chiral Ruthenium Lewis Acids

CHIMIA International Journal for Chemistry, 2011

Chiral single-point binding ruthenium Lewis acid catalysts [Ru(acetone)((S,S)-BIPHOP-F)(Cp)][SbF6... more Chiral single-point binding ruthenium Lewis acid catalysts [Ru(acetone)((S,S)-BIPHOP-F)(Cp)][SbF6]((S,S)-1a) and [Ru(acetone)((S,S)-BIPHOP-F)(indenyl)][SbF6] ((S,S)-1b) efficiently catalyze intramolecular DielsAlder (IMDA) reactions of trienals under mild conditions to afford the endo cycloaddition products as the major products in good yields with high diastereo- and enantioselectivities.

Research paper thumbnail of CCDC 1473050: Experimental Crystal Structure Determination

An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Research paper thumbnail of One point binding chiral ruthenium Lewis acid catalysts: asymmetric intramolecular Diels-Alder reactions and conformational studies

Half-sandwich chiral electron poor one-point binding ruthenium catalyst that I focused on was one... more Half-sandwich chiral electron poor one-point binding ruthenium catalyst that I focused on was one of the research interests in the Kundig group. A more general aim was to apply these catalysts to new transformations, expanding the range of applications that these complexes can satisfactorily catalyze. Only one successful example of asymmetric type 2 IMDA cycloaddition was reported. The challenges arise from the facts that several inconsistencies remain in the reported structure assignment of ledol. We therefore employed the crucial intermediate for the first total synthesis of ent-ledol to provide in good yield with excellent ee. The conformational studies of Ru-dienophile complexes with NOESY and ROESY experiments revealed a conformationally coordinate structure with correlations between dienophile protons and Cp/Indenyl ‘roof' or chiral BIPHOP-F ligand protons of catalyst part. These NMR results helped to explain the ground state conformations in solution that probably corresp...

Research paper thumbnail of Heat-cured poly(methyl methacrylate) resin incorporated with different food preservatives as an anti-microbial denture base material

Journal of Dental Sciences, 2021

Background/purpose The colonization of microorganisms onto denture bases is one common problem th... more Background/purpose The colonization of microorganisms onto denture bases is one common problem that can contribute to oral diseases. Herein, three food preservatives, including zinc oxide, potassium sorbate, and sodium metabisulfite were introduced as anti-microbial additives into a heat-polymerized poly(methyl methacrylate) (PMMA). Materials and methods Relative microbial reductions of the modified PMMA resins against Staphylococcus aureus, Pseudomonas aeruginosa, and Candida albicans were evaluated. The in vitro cytotoxicity of the materials was measured against mouse fibroblast L929 cells. A three-point flexural test was performed to determine a flexural strength and modulus properties of the materials. Results The incorporation of all preservative agents into the material diminished the microbial growth of three microbial species. The PMMA resin combined with sodium metabisulfite exhibited the greatest anti-microbial activity that reduced almost all bacterial cells and about 40%...

Research paper thumbnail of Asymmetric intramolecular Diels-Alder reactions of trienals catalyzed by chiral ruthenium Lewis acids

Chimia, 2011

Chiral single-point binding ruthenium Lewis acid catalysts [Ru(acetone)((S,S)-BIPHOP-F)(Cp)][SbF6... more Chiral single-point binding ruthenium Lewis acid catalysts [Ru(acetone)((S,S)-BIPHOP-F)(Cp)][SbF6] ((S,S)-1a) and [Ru(acetone)((S,S)-BIPHOP-F)(indenyl)][SbF6] ((S,S)-1b) efficiently catalyze intramolecular Diels-Alder (IMDA) reactions of trienals under mild conditions to afford the endo cycloaddition products as the major products in good yields with high diastereo- and enantioselectivities.

Research paper thumbnail of RutheniumLewisAcid-Catalyzed AsymmetricDiels-AlderReactions: Reverse-Face Selectivity forα,β-Unsaturated Aldehydes and Ketones

Helvetica Chimica Acta, 2016

Research paper thumbnail of One point binding chiral ruthenium Lewis acid catalysts: asymmetric intramolecular Diels-Alder reactions and conformational studies

Research paper thumbnail of Intramolecular acylation of α-sulfinyl carbanions with masked α,β-unsaturated esters: a general strategy to 5-alkylidene-2-cyclopentenones

Tetrahedron, Feb 19, 2007

ABSTRACT A convenient synthesis of 4-hydroxy spiro[4.n]alk-2-ene-1-ones and spiro [4.n]alk-2-ene-... more ABSTRACT A convenient synthesis of 4-hydroxy spiro[4.n]alk-2-ene-1-ones and spiro [4.n]alk-2-ene-1,4-diones, which involves the intramolecular acylation of α-sulfinyl carbanions followed by pyrolysis and/or oxidation, is described.

Research paper thumbnail of Asymmetric intramolecular Diels-Alder reactions of trienals catalyzed by chiral ruthenium Lewis acids

CHIMIA International Journal for Chemistry

Chiral single-point binding ruthenium Lewis acid catalysts [Ru(acetone)((S,S)-BIPHOP-F)(Cp)][SbF6... more Chiral single-point binding ruthenium Lewis acid catalysts [Ru(acetone)((S,S)-BIPHOP-F)(Cp)][SbF6] ((S,S)-1a) and [Ru(acetone)((S,S)-BIPHOP-F)(indenyl)][SbF6] ((S,S)-1b) efficiently catalyze intramolecular Diels-Alder (IMDA) reactions of trienals under mild conditions to afford the endo cycloaddition products as the major products in good yields with high diastereo- and enantioselectivities.

Research paper thumbnail of Intramolecular acylation of α-sulfinyl carbanions with masked α,β-unsaturated esters: a general strategy to 5-alkylidene-2-cyclopentenones

Tetrahedron, 2007

ABSTRACT A general method for the preparation of 5-alkylidene-2-cyclopentenones and their 2-pheny... more ABSTRACT A general method for the preparation of 5-alkylidene-2-cyclopentenones and their 2-phenylsulfanyl substituted derivatives, involving the intramolecular acylation of α-sulfinyl carbanions with cyclopentadiene-α,β-unsaturated esters as the key reaction followed by flash vacuum pyrolysis, is described. The reactions start from readily available Diels–Alder adducts, synthons of α-carbanions of α,β-unsaturated esters.

Research paper thumbnail of Chiral Ruthenium Lewis Acid Catalyzed Intramolecular Diels−Alder Reactions

Organic Letters, 2010

Single point binding ruthenium Lewis acid catalysts [Ru(acetone)(S,S)-BIPHOP-F)Cp][SbF(6)] ((S,S)... more Single point binding ruthenium Lewis acid catalysts [Ru(acetone)(S,S)-BIPHOP-F)Cp][SbF(6)] ((S,S)-1b) and [Ru(acetone)(S,S)-BIPHOP-F)(indenyl)][SbF(6)] ((S,S)-1c) efficiently catalyze intramolecular Diels-Alder (IMDA) reactions under mild conditions to afford the endo cycloaddition products as the major product in excellent yields with high diastereo- and enantioselectivities.

Research paper thumbnail of Intramolecular Diels–Alder reactions using chiral ruthenium Lewis acids and application in the total synthesis of ent-ledol

Organic & Biomolecular Chemistry, 2011

One-point binding chiral ruthenium Lewis acids incorporating the C(2)-symmetric electron-poor bid... more One-point binding chiral ruthenium Lewis acids incorporating the C(2)-symmetric electron-poor bidentate phosphinite ligand BIPHOP-F and a Cp or an indenyl 'roof' can efficiently catalyze asymmetric intramolecular Diels-Alder reactions of trienes to form bicyclic adducts with good to excellent asymmetric induction. This reaction forms the key step in a total synthesis of ent-ledol in 96% ee. The synthesis also helps to clarify the stereochemical assignment of ledol and inconsistencies in the measured optical rotation.

Research paper thumbnail of Morita−Baylis−Hillman Reaction of Masked 5-Alkylidene-2-cyclopentenones:  General Entry to 5-Alkylidene-2-(hydroxyalkyl)- 2-cyclopentenones

The Journal of Organic Chemistry, 2007

Research paper thumbnail of Reactions of Trienals Catalyzed by Chiral Ruthenium Lewis Acids

CHIMIA International Journal for Chemistry, 2011

Chiral single-point binding ruthenium Lewis acid catalysts [Ru(acetone)((S,S)-BIPHOP-F)(Cp)][SbF6... more Chiral single-point binding ruthenium Lewis acid catalysts [Ru(acetone)((S,S)-BIPHOP-F)(Cp)][SbF6]((S,S)-1a) and [Ru(acetone)((S,S)-BIPHOP-F)(indenyl)][SbF6] ((S,S)-1b) efficiently catalyze intramolecular DielsAlder (IMDA) reactions of trienals under mild conditions to afford the endo cycloaddition products as the major products in good yields with high diastereo- and enantioselectivities.

Research paper thumbnail of CCDC 1473050: Experimental Crystal Structure Determination

An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Research paper thumbnail of One point binding chiral ruthenium Lewis acid catalysts: asymmetric intramolecular Diels-Alder reactions and conformational studies

Half-sandwich chiral electron poor one-point binding ruthenium catalyst that I focused on was one... more Half-sandwich chiral electron poor one-point binding ruthenium catalyst that I focused on was one of the research interests in the Kundig group. A more general aim was to apply these catalysts to new transformations, expanding the range of applications that these complexes can satisfactorily catalyze. Only one successful example of asymmetric type 2 IMDA cycloaddition was reported. The challenges arise from the facts that several inconsistencies remain in the reported structure assignment of ledol. We therefore employed the crucial intermediate for the first total synthesis of ent-ledol to provide in good yield with excellent ee. The conformational studies of Ru-dienophile complexes with NOESY and ROESY experiments revealed a conformationally coordinate structure with correlations between dienophile protons and Cp/Indenyl ‘roof' or chiral BIPHOP-F ligand protons of catalyst part. These NMR results helped to explain the ground state conformations in solution that probably corresp...

Research paper thumbnail of Heat-cured poly(methyl methacrylate) resin incorporated with different food preservatives as an anti-microbial denture base material

Journal of Dental Sciences, 2021

Background/purpose The colonization of microorganisms onto denture bases is one common problem th... more Background/purpose The colonization of microorganisms onto denture bases is one common problem that can contribute to oral diseases. Herein, three food preservatives, including zinc oxide, potassium sorbate, and sodium metabisulfite were introduced as anti-microbial additives into a heat-polymerized poly(methyl methacrylate) (PMMA). Materials and methods Relative microbial reductions of the modified PMMA resins against Staphylococcus aureus, Pseudomonas aeruginosa, and Candida albicans were evaluated. The in vitro cytotoxicity of the materials was measured against mouse fibroblast L929 cells. A three-point flexural test was performed to determine a flexural strength and modulus properties of the materials. Results The incorporation of all preservative agents into the material diminished the microbial growth of three microbial species. The PMMA resin combined with sodium metabisulfite exhibited the greatest anti-microbial activity that reduced almost all bacterial cells and about 40%...

Research paper thumbnail of Asymmetric intramolecular Diels-Alder reactions of trienals catalyzed by chiral ruthenium Lewis acids

Chimia, 2011

Chiral single-point binding ruthenium Lewis acid catalysts [Ru(acetone)((S,S)-BIPHOP-F)(Cp)][SbF6... more Chiral single-point binding ruthenium Lewis acid catalysts [Ru(acetone)((S,S)-BIPHOP-F)(Cp)][SbF6] ((S,S)-1a) and [Ru(acetone)((S,S)-BIPHOP-F)(indenyl)][SbF6] ((S,S)-1b) efficiently catalyze intramolecular Diels-Alder (IMDA) reactions of trienals under mild conditions to afford the endo cycloaddition products as the major products in good yields with high diastereo- and enantioselectivities.

Research paper thumbnail of RutheniumLewisAcid-Catalyzed AsymmetricDiels-AlderReactions: Reverse-Face Selectivity forα,β-Unsaturated Aldehydes and Ketones

Helvetica Chimica Acta, 2016

Research paper thumbnail of One point binding chiral ruthenium Lewis acid catalysts: asymmetric intramolecular Diels-Alder reactions and conformational studies

Research paper thumbnail of Intramolecular acylation of α-sulfinyl carbanions with masked α,β-unsaturated esters: a general strategy to 5-alkylidene-2-cyclopentenones

Tetrahedron, Feb 19, 2007

ABSTRACT A convenient synthesis of 4-hydroxy spiro[4.n]alk-2-ene-1-ones and spiro [4.n]alk-2-ene-... more ABSTRACT A convenient synthesis of 4-hydroxy spiro[4.n]alk-2-ene-1-ones and spiro [4.n]alk-2-ene-1,4-diones, which involves the intramolecular acylation of α-sulfinyl carbanions followed by pyrolysis and/or oxidation, is described.

Research paper thumbnail of Asymmetric intramolecular Diels-Alder reactions of trienals catalyzed by chiral ruthenium Lewis acids

CHIMIA International Journal for Chemistry

Chiral single-point binding ruthenium Lewis acid catalysts [Ru(acetone)((S,S)-BIPHOP-F)(Cp)][SbF6... more Chiral single-point binding ruthenium Lewis acid catalysts [Ru(acetone)((S,S)-BIPHOP-F)(Cp)][SbF6] ((S,S)-1a) and [Ru(acetone)((S,S)-BIPHOP-F)(indenyl)][SbF6] ((S,S)-1b) efficiently catalyze intramolecular Diels-Alder (IMDA) reactions of trienals under mild conditions to afford the endo cycloaddition products as the major products in good yields with high diastereo- and enantioselectivities.

Research paper thumbnail of Intramolecular acylation of α-sulfinyl carbanions with masked α,β-unsaturated esters: a general strategy to 5-alkylidene-2-cyclopentenones

Tetrahedron, 2007

ABSTRACT A general method for the preparation of 5-alkylidene-2-cyclopentenones and their 2-pheny... more ABSTRACT A general method for the preparation of 5-alkylidene-2-cyclopentenones and their 2-phenylsulfanyl substituted derivatives, involving the intramolecular acylation of α-sulfinyl carbanions with cyclopentadiene-α,β-unsaturated esters as the key reaction followed by flash vacuum pyrolysis, is described. The reactions start from readily available Diels–Alder adducts, synthons of α-carbanions of α,β-unsaturated esters.

Research paper thumbnail of Chiral Ruthenium Lewis Acid Catalyzed Intramolecular Diels−Alder Reactions

Organic Letters, 2010

Single point binding ruthenium Lewis acid catalysts [Ru(acetone)(S,S)-BIPHOP-F)Cp][SbF(6)] ((S,S)... more Single point binding ruthenium Lewis acid catalysts [Ru(acetone)(S,S)-BIPHOP-F)Cp][SbF(6)] ((S,S)-1b) and [Ru(acetone)(S,S)-BIPHOP-F)(indenyl)][SbF(6)] ((S,S)-1c) efficiently catalyze intramolecular Diels-Alder (IMDA) reactions under mild conditions to afford the endo cycloaddition products as the major product in excellent yields with high diastereo- and enantioselectivities.