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Hyeon-kyu Lee - One of the best experts on this subject based on the ideXlab platform.
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dbu promoted dynamic kinetic resolution in rh catalyzed asymmetric transfer hydrogenation of 5 alkyl cyclic Sulfamidate imines stereoselective synthesis of functionalized 1 2 amino alcohols
Journal of Organic Chemistry, 2018Co-Authors: Hyeong Rae Kim, Raghavendra Achary, Hyeon-kyu LeeAbstract:Dynamic kinetic resolution (DKR)-driven asymmetric transfer hydrogenation of 5-alkyl cyclic Sulfamidate imine produces the corresponding Sulfamidate with excellent levels of diastereo- and enantioselectivity by employing a HCO2H/DBU mixture as the hydrogen source in the presence of the Noyori-type chiral Rh-catalyst at room temperature for 1 h. In this process, DKR was induced by DBU-promoted rapid racemization of the substrate. Stereoselective transformations of the resulting cyclic Sulfamidates to functionalized enantiomerically enriched 1,2-amino alcohol and chiral amine substances are also described.
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DBU-Promoted Dynamic Kinetic Resolution in Rh-Catalyzed Asymmetric Transfer Hydrogenation of 5‑Alkyl Cyclic Sulfamidate Imines: Stereoselective Synthesis of Functionalized 1,2-Amino Alcohols
2018Co-Authors: Hyeong Rae Kim, Raghavendra Achary, Hyeon-kyu LeeAbstract:Dynamic kinetic resolution (DKR)-driven asymmetric transfer hydrogenation of 5-alkyl cyclic Sulfamidate imine produces the corresponding Sulfamidate with excellent levels of diastereo- and enantioselectivity by employing a HCO2H/DBU mixture as the hydrogen source in the presence of the Noyori-type chiral Rh-catalyst at room temperature for 1 h. In this process, DKR was induced by DBU-promoted rapid racemization of the substrate. Stereoselective transformations of the resulting cyclic Sulfamidates to functionalized enantiomerically enriched 1,2-amino alcohol and chiral amine substances are also described
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stereoselective synthesis of functionalized 1 3 disubstituted isoindolines via rh iii catalyzed tandem oxidative olefination cyclization of 4 aryl cyclic Sulfamidate 5 carboxylates
Journal of Organic Chemistry, 2017Co-Authors: Raghavendra Achary, Ina Jung, Semi Son, Hyeon-kyu LeeAbstract:A new method for the direct, stereoselective synthesis of highly functionalized 1,3-disubstituted isoindolines 6 from enantiomerically enriched cyclic 4-aryl-Sulfamidate-5-carboxylates (5) is described. The process involves Sulfamidate directed, Rh(III)-catalyzed tandem ortho C–H olefination of the 4-aryl-Sulfamidate-5-carboxylates and subsequent cyclization by aza-Michael addition. In the reaction, which generates trans-1,3-disubstituted isoindolines exclusively, the configurational integrity of the stereogenic center in the starting cyclic Sulfamidate is completely retained in the product. Examples are provided which show that the cyclic Sulfamidate moiety not only serves as a chiral directing group but also as a versatile handle for further functionalization of the generated isoindoline ring system.
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Stereoselective Synthesis of Functionalized 1,3-Disubstituted Isoindolines via Rh(III)-Catalyzed Tandem Oxidative Olefination-Cyclization of 4‑Aryl-cyclic Sulfamidate-5-Carboxylates
2017Co-Authors: Raghavendra Achary, Ina Jung, Semi Son, Hyeon-kyu LeeAbstract:A new method for the direct, stereoselective synthesis of highly functionalized 1,3-disubstituted isoindolines 6 from enantiomerically enriched cyclic 4-aryl-Sulfamidate-5-carboxylates (5) is described. The process involves Sulfamidate directed, Rh(III)-catalyzed tandem ortho C–H olefination of the 4-aryl-Sulfamidate-5-carboxylates and subsequent cyclization by aza-Michael addition. In the reaction, which generates trans-1,3-disubstituted isoindolines exclusively, the configurational integrity of the stereogenic center in the starting cyclic Sulfamidate is completely retained in the product. Examples are provided which show that the cyclic Sulfamidate moiety not only serves as a chiral directing group but also as a versatile handle for further functionalization of the generated isoindoline ring system
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stereoselective synthesis of 4 substituted cyclic Sulfamidate 5 phosphonates by using rh catalyzed asymmetric transfer hydrogenation with accompanying dynamic kinetic resolution
ChemInform, 2016Co-Authors: Yeon Ji Seo, Jin-ah Kim, Hyeon-kyu LeeAbstract:Dynamic kinetic resolution driven, asymmetric transfer hydrogenation of 4-substituted cyclic Sulfamidate imine-5-phosphonates produces the corresponding cyclic Sulfamidate-5-phosphonates. The process employs a HCO2H/Et3N mixture as the hydrogen source and the chiral Rh catalysts, (R,R)- or (S,S)-Cp*RhCl(TsDPEN), and it takes place at room temperature within 1 h with high yields and high levels of stereoselectivity.
Sampak Samanta - One of the best experts on this subject based on the ideXlab platform.
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1 6 addition of vinyl p quinone methides with cyclic Sulfamidate imines access to 4 hydroxyaryl 2 6 diarylpyridines
Organic and Biomolecular Chemistry, 2020Co-Authors: Soumitra Guin, Santosh K Gudimella, Sampak SamantaAbstract:A simple and powerful one-pot regioselective 1,6-addition elimination-6π-aza-electrocyclization-aromatization reaction of vinyl/dienyl-substituted para-quinone methides with a bunch of cyclic Sulfamidate imines as 2C1N synthons promoted by DABCO as a solid organobase in an open atmosphere is reported for the first time. The above-mentioned C-C and C-N bond formation process provides good to high yields of a wide range of symmetrically and unsymmetrically 2,4,6-trisubstituted pyridines possessing a sterically hindered phenolic moiety at the C4-position with a broad substrate scope. This domino [3 + 3] cyclization reaction gives rise to several compatible functionalities under metal-free conditions. Finally, the large-scale synthesis of pyridine derivatives has been demonstrated.
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stereoselective synthesis of 3 3 disubstituted oxindoles and spirooxindoles via allylic alkylation of morita baylis hillman carbonates of isatins with cyclic Sulfamidate imines catalyzed by dabco
Journal of Organic Chemistry, 2018Co-Authors: Sanjeeva K. Arupula, Soumitra Guin, Anubha Yadav, Shaikh M. Mobin, Sampak SamantaAbstract:An efficient, organocatalytic, and ecofriendly method has been developed for the quick construction of a wide array of 3,3-disubstituted oxindoles in good to excellent yields and diastereomeric ratio (up to ≤96:4) with excellent functional group tolerance via an allylic alkylation reaction of cyclic Sulfamidate imines with a number of MBH carbonates of isatins in 2-MeTHF as an environmentally benign solvent at room temperature using 5 mol % of DABCO. Furthermore, a metal-free-based one-shot synthesis of a medicinally promising polycyclic spirooxindole with an all-carbon spirocenter has been achieved with outstanding dr value (up to ≤99:1).
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Stereoselective Synthesis of 3,3-Disubstituted Oxindoles and Spirooxindoles via Allylic Alkylation of Morita–Baylis–Hillman Carbonates of Isatins with Cyclic Sulfamidate Imines Catalyzed by DABCO
2018Co-Authors: Sanjeeva K. Arupula, Soumitra Guin, Anubha Yadav, Shaikh M. Mobin, Sampak SamantaAbstract:An efficient, organocatalytic, and ecofriendly method has been developed for the quick construction of a wide array of 3,3-disubstituted oxindoles in good to excellent yields and diastereomeric ratio (up to ≤96:4) with excellent functional group tolerance via an allylic alkylation reaction of cyclic Sulfamidate imines with a number of MBH carbonates of isatins in 2-MeTHF as an environmentally benign solvent at room temperature using 5 mol % of DABCO. Furthermore, a metal-free-based one-shot synthesis of a medicinally promising polycyclic spirooxindole with an all-carbon spirocenter has been achieved with outstanding dr value (up to ≤99:1)
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metal and solvent free approach to diversely substituted picolinates via domino reaction of cyclic Sulfamidate imines with β γ unsaturated α ketocarbonyls
Journal of Organic Chemistry, 2017Co-Authors: Soumen Biswas, Soumitra Guin, Debashis Majee, Sampak SamantaAbstract:An efficient, solvent-free, and eco-friendly domino reaction of 5/6-membered cyclic Sulfamidate imines with a variety of β,γ-unsaturated α-ketocarbonyls in neat conditions under MW irradiation promoted by DABCO as a solid organobase has been developed for the rapid construction of a novel class of densely functionalized picolinates. This interesting metal–solvent-free tactic allows a wide range of useful functionalities on the aryl rings and delivers good to excellent yields of the aforesaid aza-heterocycles within short time spans (20–40 min). A biologically promising imidazo[1,2-a]pyridine was successfully synthesized through our unique procedure.
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a metal free based new approach to 2 4 disubstituted pyridines via one pot sequential reaction of cyclic Sulfamidate imines with β substituted acroleins
ChemistrySelect, 2017Co-Authors: Debashis Majee, Soumitra Guin, Soumen Biswas, Sampak SamantaAbstract:A novel and efficient L-proline catalyzed Michael reaction of several 4-aryl/heteroaryl-substituted cyclic Sulfamidate imines with a variety of β-styryl/aryl/alkyl-substituted acroleins, followed by in situ elimination-iminocyclization-dehydration sequence process in the presence of DABCO as a base is reported for the first time. By this unconventional one-pot sequential protocol, a number of 2-aryl/heteroaryl-4-styrylpyridines and 2,4-diarylpyridines have been prepared in good to high yields under metal-free conditions. Besides, the synthesized 4-styrylpyridine derivatives were also further utilized for the synthesis of commercially as well as pharmaceutically important 2-arylisonicotinic acids.
Raghavendra Achary - One of the best experts on this subject based on the ideXlab platform.
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dbu promoted dynamic kinetic resolution in rh catalyzed asymmetric transfer hydrogenation of 5 alkyl cyclic Sulfamidate imines stereoselective synthesis of functionalized 1 2 amino alcohols
Journal of Organic Chemistry, 2018Co-Authors: Hyeong Rae Kim, Raghavendra Achary, Hyeon-kyu LeeAbstract:Dynamic kinetic resolution (DKR)-driven asymmetric transfer hydrogenation of 5-alkyl cyclic Sulfamidate imine produces the corresponding Sulfamidate with excellent levels of diastereo- and enantioselectivity by employing a HCO2H/DBU mixture as the hydrogen source in the presence of the Noyori-type chiral Rh-catalyst at room temperature for 1 h. In this process, DKR was induced by DBU-promoted rapid racemization of the substrate. Stereoselective transformations of the resulting cyclic Sulfamidates to functionalized enantiomerically enriched 1,2-amino alcohol and chiral amine substances are also described.
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DBU-Promoted Dynamic Kinetic Resolution in Rh-Catalyzed Asymmetric Transfer Hydrogenation of 5‑Alkyl Cyclic Sulfamidate Imines: Stereoselective Synthesis of Functionalized 1,2-Amino Alcohols
2018Co-Authors: Hyeong Rae Kim, Raghavendra Achary, Hyeon-kyu LeeAbstract:Dynamic kinetic resolution (DKR)-driven asymmetric transfer hydrogenation of 5-alkyl cyclic Sulfamidate imine produces the corresponding Sulfamidate with excellent levels of diastereo- and enantioselectivity by employing a HCO2H/DBU mixture as the hydrogen source in the presence of the Noyori-type chiral Rh-catalyst at room temperature for 1 h. In this process, DKR was induced by DBU-promoted rapid racemization of the substrate. Stereoselective transformations of the resulting cyclic Sulfamidates to functionalized enantiomerically enriched 1,2-amino alcohol and chiral amine substances are also described
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stereoselective synthesis of functionalized 1 3 disubstituted isoindolines via rh iii catalyzed tandem oxidative olefination cyclization of 4 aryl cyclic Sulfamidate 5 carboxylates
Journal of Organic Chemistry, 2017Co-Authors: Raghavendra Achary, Ina Jung, Semi Son, Hyeon-kyu LeeAbstract:A new method for the direct, stereoselective synthesis of highly functionalized 1,3-disubstituted isoindolines 6 from enantiomerically enriched cyclic 4-aryl-Sulfamidate-5-carboxylates (5) is described. The process involves Sulfamidate directed, Rh(III)-catalyzed tandem ortho C–H olefination of the 4-aryl-Sulfamidate-5-carboxylates and subsequent cyclization by aza-Michael addition. In the reaction, which generates trans-1,3-disubstituted isoindolines exclusively, the configurational integrity of the stereogenic center in the starting cyclic Sulfamidate is completely retained in the product. Examples are provided which show that the cyclic Sulfamidate moiety not only serves as a chiral directing group but also as a versatile handle for further functionalization of the generated isoindoline ring system.
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Stereoselective Synthesis of Functionalized 1,3-Disubstituted Isoindolines via Rh(III)-Catalyzed Tandem Oxidative Olefination-Cyclization of 4‑Aryl-cyclic Sulfamidate-5-Carboxylates
2017Co-Authors: Raghavendra Achary, Ina Jung, Semi Son, Hyeon-kyu LeeAbstract:A new method for the direct, stereoselective synthesis of highly functionalized 1,3-disubstituted isoindolines 6 from enantiomerically enriched cyclic 4-aryl-Sulfamidate-5-carboxylates (5) is described. The process involves Sulfamidate directed, Rh(III)-catalyzed tandem ortho C–H olefination of the 4-aryl-Sulfamidate-5-carboxylates and subsequent cyclization by aza-Michael addition. In the reaction, which generates trans-1,3-disubstituted isoindolines exclusively, the configurational integrity of the stereogenic center in the starting cyclic Sulfamidate is completely retained in the product. Examples are provided which show that the cyclic Sulfamidate moiety not only serves as a chiral directing group but also as a versatile handle for further functionalization of the generated isoindoline ring system
Shaikh M. Mobin - One of the best experts on this subject based on the ideXlab platform.
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stereoselective synthesis of 3 3 disubstituted oxindoles and spirooxindoles via allylic alkylation of morita baylis hillman carbonates of isatins with cyclic Sulfamidate imines catalyzed by dabco
Journal of Organic Chemistry, 2018Co-Authors: Sanjeeva K. Arupula, Soumitra Guin, Anubha Yadav, Shaikh M. Mobin, Sampak SamantaAbstract:An efficient, organocatalytic, and ecofriendly method has been developed for the quick construction of a wide array of 3,3-disubstituted oxindoles in good to excellent yields and diastereomeric ratio (up to ≤96:4) with excellent functional group tolerance via an allylic alkylation reaction of cyclic Sulfamidate imines with a number of MBH carbonates of isatins in 2-MeTHF as an environmentally benign solvent at room temperature using 5 mol % of DABCO. Furthermore, a metal-free-based one-shot synthesis of a medicinally promising polycyclic spirooxindole with an all-carbon spirocenter has been achieved with outstanding dr value (up to ≤99:1).
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Stereoselective Synthesis of 3,3-Disubstituted Oxindoles and Spirooxindoles via Allylic Alkylation of Morita–Baylis–Hillman Carbonates of Isatins with Cyclic Sulfamidate Imines Catalyzed by DABCO
2018Co-Authors: Sanjeeva K. Arupula, Soumitra Guin, Anubha Yadav, Shaikh M. Mobin, Sampak SamantaAbstract:An efficient, organocatalytic, and ecofriendly method has been developed for the quick construction of a wide array of 3,3-disubstituted oxindoles in good to excellent yields and diastereomeric ratio (up to ≤96:4) with excellent functional group tolerance via an allylic alkylation reaction of cyclic Sulfamidate imines with a number of MBH carbonates of isatins in 2-MeTHF as an environmentally benign solvent at room temperature using 5 mol % of DABCO. Furthermore, a metal-free-based one-shot synthesis of a medicinally promising polycyclic spirooxindole with an all-carbon spirocenter has been achieved with outstanding dr value (up to ≤99:1)
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domino reaction of cyclic Sulfamidate imines with morita baylis hillman acetates promoted by dabco a metal free approach to functionalized nicotinic acid derivatives
Organic and Biomolecular Chemistry, 2017Co-Authors: Debashis Majee, Shaikh M. Mobin, Soumen Biswas, Sampak SamantaAbstract:A facile, green, metal-free new one-pot synthetic strategy has been developed for easy access to a wide array of medicinally promising functionalized pyridines having an ester, a nitrile or an acetyl group at the C-3 position in good to excellent yields via a domino SN2/elimination/6π-aza-electrocyclization/aromatization reaction of several 4-aryl/hetero-aryl-substituted 5-membered cyclic Sulfamidate imines with a broad range of MBH acetates of acrylate/acrylonitrile/MVK in 2-MeTHF promoted by DABCO as an organobase under an O2 atmosphere. Moreover, a biologically interesting triazolopyridine derivative was achieved through a unique procedure.
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access to 4 6 diarylpicolinates via a domino reaction of cyclic Sulfamidate imines with morita baylis hillman acetates of nitroolefins nitrodienes
Journal of Organic Chemistry, 2016Co-Authors: Debashis Majee, Shaikh M. Mobin, Soumen Biswas, Sampak SamantaAbstract:An interesting domino reaction of 5-membered cyclic Sulfamidate imines with a variety of Morita–Baylis–Hillman acetates of nitroolefins/nitrodienes in the presence of DABCO as an organic base at 55 °C is reported for the first time. This new synthetic strategy provides a series of pharmacologically interesting 4,6-diarylpicolinates in high to excellent yields and allows several compatible functionalities on aryl rings. Moreover, the biologically interesting imidazo[1,2-a]pyridine (alpidem derivative) has been prepared in high chemical yield through a unique procedure.
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Access to 4,6-Diarylpicolinates via a Domino Reaction of Cyclic Sulfamidate Imines with Morita–Baylis–Hillman Acetates of Nitroolefins/Nitrodienes
2016Co-Authors: Debashis Majee, Shaikh M. Mobin, Soumen Biswas, Sampak SamantaAbstract:An interesting domino reaction of 5-membered cyclic Sulfamidate imines with a variety of Morita–Baylis–Hillman acetates of nitroolefins/nitrodienes in the presence of DABCO as an organic base at 55 °C is reported for the first time. This new synthetic strategy provides a series of pharmacologically interesting 4,6-diarylpicolinates in high to excellent yields and allows several compatible functionalities on aryl rings. Moreover, the biologically interesting imidazo[1,2-a]pyridine (alpidem derivative) has been prepared in high chemical yield through a unique procedure
Timothy Gallagher - One of the best experts on this subject based on the ideXlab platform.
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copper catalyzed borylation of cyclic Sulfamidates access to enantiomerically pure β and γ amino alkyl boronic esters
European Journal of Organic Chemistry, 2016Co-Authors: Nina Ursinyova, Robin B Bedford, Timothy GallagherAbstract:Cyclic Sulfamidates undergo borylation under copper-catalyzed conditions using B2pin2 to give enantiomerically (and diasteromerically) defined (aminoalkyl)boronic esters. External iodide is essential, but the intermediacy of simple alkyl iodides has been excluded; N-sulfated intermediates are key in the borylation sequence. Based on stereochemical studies and trapping experiments, the involvement of carbon-centered radicals under these copper-catalyzed conditions appears likely.
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enantiopure 1 4 benzoxazines via 1 2 cyclic Sulfamidates synthesis of levofloxacin
Organic Letters, 2007Co-Authors: John F Bower, Peter Szeto, Timothy GallagherAbstract:1,2-Cyclic Sulfamidates undergo efficient and regiospecific nucleophilic cleavage with 2-bromophenols (and related anilines and thiophenols), followed by Pd(0)-mediated amination to provide an entry to substituted and enantiomerically pure 1,4-benzoxazines (and quinoxalines and 1,4-benzothiazines). This chemistry provides a short and efficient entry to (3S)-3-methyl-1,4-benzoxazine 19, a late stage intermediate in the synthesis of levofloxacin.
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1 2 cyclic Sulfamidates as versatile precursors to thiomorpholines and piperazines
Organic Letters, 2003Co-Authors: Andrew Williams, Suda Chakthong, Diane Gray, Ron M Lawrence, Timothy GallagherAbstract:1,2-Cyclic Sulfamidates undergo regiospecific nucleophilic displacement with either methyl thioglycolate or α-amino esters, followed by lactamization (thermal, base-mediated, or cyanide-catalyzed), to give thiomorpholin-3-ones and piperazin-2-ones.
