The Experts below are selected from a list of 456 Experts worldwide ranked by ideXlab platform
Daniel Seidel - One of the best experts on this subject based on the ideXlab platform.
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direct formation of oxocarbenium ions under weakly acidic conditions catalytic enantioselective oxa pictet spengler reactions
Journal of the American Chemical Society, 2016Co-Authors: Chenfei Zhao, Shawn B Chen, Daniel SeidelAbstract:Two catalysts, an amine HCl salt and a bisthiourea, work in concert to enable the generation of oxocarbenium ions under mild conditions. The amine catalyst generates an iminium ion of sufficient electrophilicity to enable 1,2-attack by an alcohol. Catalyst turnover is achieved by amine elimination with concomitant formation of an oxocarbenium intermediate. The bisthiourea catalyst accelerates all of the steps of the reaction and controls the stereoselectivity via anion binding/ion pair formation. This new concept was applied to direct catalytic enantioselective oxa-Pictet–Spengler reactions of Tryptophol with aldehydes.
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Direct Formation of Oxocarbenium Ions under Weakly Acidic Conditions: Catalytic Enantioselective Oxa-Pictet–Spengler Reactions
2016Co-Authors: Chenfei Zhao, Shawn B Chen, Daniel SeidelAbstract:Two catalysts, an amine HCl salt and a bisthiourea, work in concert to enable the generation of oxocarbenium ions under mild conditions. The amine catalyst generates an iminium ion of sufficient electrophilicity to enable 1,2-attack by an alcohol. Catalyst turnover is achieved by amine elimination with concomitant formation of an oxocarbenium intermediate. The bisthiourea catalyst accelerates all of the steps of the reaction and controls the stereoselectivity via anion binding/ion pair formation. This new concept was applied to direct catalytic enantioselective oxa-Pictet–Spengler reactions of Tryptophol with aldehydes
Shuli You - One of the best experts on this subject based on the ideXlab platform.
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dearomatization of Tryptophols via a vanadium catalyzed asymmetric epoxidation and ring opening cascade
ChemInform, 2014Co-Authors: Long Han, Chuan Liu, Wei Zhang, Xiaoxin Shi, Shuli YouAbstract:Substrates bearing a methyl group at C5, C6, and C7-positions require much longer reaction times.
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dearomatization of Tryptophols via a vanadium catalyzed asymmetric epoxidation and ring opening cascade
Chemical Communications, 2014Co-Authors: Long Han, Chuan Liu, Wei Zhang, Xiaoxin Shi, Shuli YouAbstract:An enantioselective epoxidation of Tryptophols followed by an intramolecular epoxide opening reaction was realized by chiral vanadium catalysts derived from C2 symmetric bis-hydroxamic acid (BHA) ligands. 3a-Hydroxyfuroindoline derivatives with up to 89% yield and 90% ee were obtained under mild reaction conditions.
Weiqing Xie - One of the best experts on this subject based on the ideXlab platform.
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highly asymmetric bromocyclization of Tryptophol unexpected accelerating effect of dabco derived bromine complex
ChemInform, 2014Co-Authors: Huan Liu, Guangde Jiang, Xixian Pan, Xiaolong Wan, Yisheng Lai, Weiqing XieAbstract:Bromocyclization of Tryptophol derivatives is achieved in the presence of chiral BINOL-derived phosphoric acid catalyst and DABCO derived brominating agents to produce 3-bromofluoroindolines in high yields and excellent enantioselectivities.
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highly asymmetric bromocyclization of Tryptophol unexpected accelerating effect of dabco derived bromine complex
Organic Letters, 2014Co-Authors: Huan Liu, Guangde Jiang, Xixian Pan, Xiaolong Wan, Yisheng Lai, Weiqing XieAbstract:Highly asymmetric bromocyclization of Tryptophol by using chiral anionic phase-transfer catalyst and DABCO-derived brominating reagent is described. Optimization of the reaction conditions revealed that the reaction rate was accelerated together with improvement of enantioselectivity by addition of catalytic DABCO-derived brominating reagent. From Tryptophol, 3-bromofuroindoline could be directly obtained in excellent enantioselectivities by employing this novel methodology.
Chenfei Zhao - One of the best experts on this subject based on the ideXlab platform.
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direct formation of oxocarbenium ions under weakly acidic conditions catalytic enantioselective oxa pictet spengler reactions
Journal of the American Chemical Society, 2016Co-Authors: Chenfei Zhao, Shawn B Chen, Daniel SeidelAbstract:Two catalysts, an amine HCl salt and a bisthiourea, work in concert to enable the generation of oxocarbenium ions under mild conditions. The amine catalyst generates an iminium ion of sufficient electrophilicity to enable 1,2-attack by an alcohol. Catalyst turnover is achieved by amine elimination with concomitant formation of an oxocarbenium intermediate. The bisthiourea catalyst accelerates all of the steps of the reaction and controls the stereoselectivity via anion binding/ion pair formation. This new concept was applied to direct catalytic enantioselective oxa-Pictet–Spengler reactions of Tryptophol with aldehydes.
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Direct Formation of Oxocarbenium Ions under Weakly Acidic Conditions: Catalytic Enantioselective Oxa-Pictet–Spengler Reactions
2016Co-Authors: Chenfei Zhao, Shawn B Chen, Daniel SeidelAbstract:Two catalysts, an amine HCl salt and a bisthiourea, work in concert to enable the generation of oxocarbenium ions under mild conditions. The amine catalyst generates an iminium ion of sufficient electrophilicity to enable 1,2-attack by an alcohol. Catalyst turnover is achieved by amine elimination with concomitant formation of an oxocarbenium intermediate. The bisthiourea catalyst accelerates all of the steps of the reaction and controls the stereoselectivity via anion binding/ion pair formation. This new concept was applied to direct catalytic enantioselective oxa-Pictet–Spengler reactions of Tryptophol with aldehydes
Long Han - One of the best experts on this subject based on the ideXlab platform.
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dearomatization of Tryptophols via a vanadium catalyzed asymmetric epoxidation and ring opening cascade
ChemInform, 2014Co-Authors: Long Han, Chuan Liu, Wei Zhang, Xiaoxin Shi, Shuli YouAbstract:Substrates bearing a methyl group at C5, C6, and C7-positions require much longer reaction times.
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dearomatization of Tryptophols via a vanadium catalyzed asymmetric epoxidation and ring opening cascade
Chemical Communications, 2014Co-Authors: Long Han, Chuan Liu, Wei Zhang, Xiaoxin Shi, Shuli YouAbstract:An enantioselective epoxidation of Tryptophols followed by an intramolecular epoxide opening reaction was realized by chiral vanadium catalysts derived from C2 symmetric bis-hydroxamic acid (BHA) ligands. 3a-Hydroxyfuroindoline derivatives with up to 89% yield and 90% ee were obtained under mild reaction conditions.
