The Experts below are selected from a list of 402 Experts worldwide ranked by ideXlab platform
Jiong Hu - One of the best experts on this subject based on the ideXlab platform.
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reaction of carbonyl compounds with trimethylsilyl propargyl dii sobutylTelluronium bromide mediated by different strong bases highly regioselective synthesis of trimethylsilyl propargyl alcohol and highly stereoselective synthesis of cis trimethylsi
Journal of Organic Chemistry, 1992Co-Authors: Zhang-lin Zhou, Yao-zeng Huang, Jiong HuAbstract:[(Trimethylsilyl)propargyl)]diisobutylTelluronium bromide (1), after being treated with allyl- or aryllithium reagent, undergoes a lithium-tellurium exchange reaction via an unstable transient tetraorganyltellurium intermediate, and the in situ generated lithium species reacts with carbonyl compounds to give (trimethylsilyl)-propargyl alcohols 2 in high yields with high regioselectivity. However, when the Telluronium salt I was treated with nonnucleophilic bases such as LDA or lithium 2,2,6,6-tetramethylpiperidide, the moderately stabilized silylated Telluronium ylide formed. The silylated Telluronium ylide reacted with carbonyl compounds to afford (trimethylsilyl)alkynyl epoxides 11 in good to excellent yields with high cis stereoselectivity
Yong Tang - One of the best experts on this subject based on the ideXlab platform.
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Telluronium salts mediated aziridination of chiral N-tert-butylsulfinylimines: highly stereoselective synthesis of optically active vinylaziridines.
Organic Letters, 2005Co-Authors: Jun-cheng Zheng, Yong Tang, Li-xin Dai, Wei-wei Liao, Xiao-xia Sun, Xiu-li Sun, Jin-geng DengAbstract:Optically active cis-2-substituted vinylaziridines are synthesized by the reaction of N-tert-butylsulfinylimines with Telluronium ylides with excellent diastereoselectivity in good to excellent yields.
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Telluronium and Sulfonium Ylides for Organic Transformation
Synlett, 2005Co-Authors: Yong Tang, Xiu-li SunAbstract:This account briefly describes the development of ylide olefination. cyclopropanation. epoxidation and aziridination. achieved in our laboratory over the last several years.
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A facile reaction of imines with Telluronium allylide. Highly stereoselective synthesis of vinylaziridines.
Chemical Communications, 2004Co-Authors: Wei-wei Liao, Xianming Deng, Yong TangAbstract:The reaction of Telluronium allylides with alkylimines, generated in situ from α-amidoalkyl sulfones, affords cis-alkylvinylarizidines with good stereoselectivity in good yields. However, the same ylides react with N-aryl imines to provide trans-vinylaziridines.
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Controllable Diastereoselective Cyclopropanation. Enantioselective Synthesis of Vinylcyclopropanes via Chiral Telluronium Ylides
Journal of the American Chemical Society, 2003Co-Authors: Wei-wei Liao, Yong TangAbstract:Novel chiral Telluronium salts 1 are designed for asymmetric synthesis of 1,3-disubstituted 2-vinylcyclopropanes. The allylides, generated in situ from the corresponding Telluronium salt in the presence of different base, reacted with α,β-unsaturated esters, ketones, and amides to afford cis-2-silylvinyl-trans-3-substituted or trans-2-silylvinyl-trans-3-substituted cyclopropane derivatives with high diastereoselectivity and excellent enantioselectivity in good to high yields. Thus, either one of the two diastereomers could be enantioselectively synthesized at will just by the choice of LiTMP/HMPA or LDA/LiBr. The first examples of catalytic ylide reaction for enantioselective synthesis of 1,3-disubstituted 2-vinylcyclopropanes with high distereoselectivity is also achieved.
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An efficient catalytic ylide route to vinyl epoxides
Tetrahedron Letters, 2003Co-Authors: Zheng-zheng Huang, Yong TangAbstract:Abstract The ylide epoxidation catalyzed by Telluronium salts provides a simple and extremely efficient route to vinyl epoxides in excellent yields. Both aromatic and aliphatic aldehydes work well. The best results were obtained by using 2 mol% of Telluronium salts with Cs2CO3 in t-BuOH.
Nobumasa Kamigata - One of the best experts on this subject based on the ideXlab platform.
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Isolation and Racemization Mechanism of Optically Active BenzylmethylphenylTelluronium Salts
European Journal of Organic Chemistry, 2010Co-Authors: Toshio Shimizu, Ryuuya Sakurai, Yoko Azami, Kazunori Hirabayashi, Nobumasa KamigataAbstract:Diastereomeric benzylmethylphenylTelluronium (1S)-(+)- and (1R)-(–)-camphor-10-sulfonates were synthesized and resolved by fractional recrystallization. The absolute configurations of the isomers were determined by X-ray crystallographic analysis. Enantiomerically pure Telluronium salts with achiral counteranions, such as tetrafluoroborate, 4-chlorobenzenesulfonate, bromide, iodide, and tetraphenylborate, were also obtained by anion-exchange reactions of the separated diastereomers. The optically active Telluronium salts possessing counteranions with a high nucleophilicity, such as bromide and iodide, were found to racemize in solution. The racemization of the Telluronium salts was found to proceed either through the formation of a tellurane by the nucleophilic addition of a counteranion to the tellurium atom followed by decomposition into methyl phenyl telluride and benzyl halide or by several pseudorotations of the tellurane.
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Synthesis and Stereochemistry of Optically Active Organic Selenium and Tellurium Compounds
Journal of Synthetic Organic Chemistry Japan, 2009Co-Authors: Toshio Shimizu, Nobumasa KamigataAbstract:Some optically active tricoordinate selenium and tellurium compounds, such as selenonium ylide, Telluronium ylide, selenonium imide, selenonium salt, Telluronium salt, and telluroxide, were isolated by means of optical resolution of corresponding diastereomeric mixtures or asymmetric syntheses. Absolute configurations of the optically active isomers obtained were determined by their X-ray crystallographic analyses, specific rotations, and circular dichroism spectra. Racemization of the isomers by pyramidal inversion or via achiral hydrate were also examined, and activation energies for the pyramidal inversion were estimated based on ab initio MO calculations.
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Palladium-catalyzed Mizoroki–Heck-type reactions of chalcogenonium trifluoromethanesulfonates
Journal of Sulfur Chemistry, 2009Co-Authors: Kazunori Hirabayashi, Nobumasa Kamigata, Yoshiko Nara, Yukiko Yamashita, Ken-ichi Kiyota, Toshio ShimizuAbstract:The reaction of dimethyl(4-methylphenyl)selenonium trifluoromethanesulfonate with butyl acrylate proceeded in the presence of palladium(II) catalyst and silver acetate to give a Mizoroki–Heck-type product. The corresponding sulfonium salt also reacted with butyl acrylate to afford the same product under similar conditions, although the yields were low. In the case of the corresponding Telluronium salt, the reaction proceeded smoothly to give a good yield.
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Homocoupling reactions using Telluronium salts
Synlett, 2005Co-Authors: Kazunori Hirabayashi, Toshio Shimizu, Yuji Takeda, Nobumasa KamigataAbstract:The homocoupling reaction of aryldimethylTelluronium iodides in the presence of a catalytic amount of palladium(II) species and two equivalents of silver(I) acetate proceeded to afford the corresponding biaryls.
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Synthesis and Stereochemistry of Optically Active Selenium and Tellurium Compounds
Phosphorus Sulfur and Silicon and The Related Elements, 2005Co-Authors: Nobumasa KamigataAbstract:The synthesis and stereochemistry of tricoordinated optically active selenium and tellurium compounds are described. Telluronium salts, Telluronium imides, and seleninic acids were prepared and optically resolved by fractional recrystallization of diastereomeric mixtures or by chromatography using a chiral column of racemic mixtures. Diphenyl dichalcogenides also were optically resolved by chiral crystallization. Their absolute configurations were determined or estimated based on X-ray crystallographic analysis, specific rotations, and circular dichroism spectra. The kinetic studies and the mechanism for the racemization were also studied.
Zhang-lin Zhou - One of the best experts on this subject based on the ideXlab platform.
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Fast atom bombardment mass spectra of Telluronium salts
Journal of Mass Spectrometry, 1992Co-Authors: Zhang-lin Zhou, Yao-zeng HuangAbstract:The fast atom bombardment (FAB) mass spectra of Telluronium salts were studied. The spectra exhibit the intact cation (C+) and cluster ions ([M + C]+). The principal fragment ions in the FAB mass spectra of Telluronium salts are [RTe]+, [R2Te]+˙, [R2Te − H]+, [RTeR′]+˙, and [RTeR′ + H]+. When the anion was [BPh4]−, interesting cluster ions such as [M + C − BPh3]+ appeared.
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reaction of carbonyl compounds with trimethylsilyl propargyl dii sobutylTelluronium bromide mediated by different strong bases highly regioselective synthesis of trimethylsilyl propargyl alcohol and highly stereoselective synthesis of cis trimethylsi
Journal of Organic Chemistry, 1992Co-Authors: Zhang-lin Zhou, Yao-zeng Huang, Jiong HuAbstract:[(Trimethylsilyl)propargyl)]diisobutylTelluronium bromide (1), after being treated with allyl- or aryllithium reagent, undergoes a lithium-tellurium exchange reaction via an unstable transient tetraorganyltellurium intermediate, and the in situ generated lithium species reacts with carbonyl compounds to give (trimethylsilyl)-propargyl alcohols 2 in high yields with high regioselectivity. However, when the Telluronium salt I was treated with nonnucleophilic bases such as LDA or lithium 2,2,6,6-tetramethylpiperidide, the moderately stabilized silylated Telluronium ylide formed. The silylated Telluronium ylide reacted with carbonyl compounds to afford (trimethylsilyl)alkynyl epoxides 11 in good to excellent yields with high cis stereoselectivity
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Novel reaction of dibutyl(cyanomethyl)Telluronium chloride with carbonyl compounds mediated by organolithium reagents: highly efficient synthesis of β-hydroxy nitriles
Journal of The Chemical Society-perkin Transactions 1, 1991Co-Authors: Zhang-lin Zhou, Lin-lan Shi, Yao-zeng HuangAbstract:Dibutyl(cyanomethyl)Telluronium chloride, a precursor of stabilized Telluronium glides, after being treated with organolithium reagents reacted with carbonyl compounds to afford β-hydroxy nitriles instead of α,β-unsaturated nitrites in excellent yields.
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Perkin communication. Formation of secondary alcohols from the reaction of trimethyl- and methyldiphenyl-Telluronium salts with aldehydes by use of organolithium reagents
Journal of The Chemical Society-perkin Transactions 1, 1990Co-Authors: Li-lan Shi, Zhang-lin Zhou, Yao-zeng HuangAbstract:The Telluronium salts (1) and (2), precursors of the non-stabilized Telluronium ylide, on treatment with organolithium reagents, reacted with aldehydes to afford secondary alcohols via tetraorganyl tellurium intermediates.
Kin-ya Akiba - One of the best experts on this subject based on the ideXlab platform.
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Synthesis and structure of pentaphenyl‐Telluronium salts of perchlorate and tetrakis{3,5‐bis(trifluoromethyl)phenyl}borate: hypervalent onium compounds
Heteroatom Chemistry, 2001Co-Authors: Mao Minoura, Takahiro Mukuda, Takao Sagami, Kin-ya AkibaAbstract:The reaction of pentaphenyltellurium chloride 2 with silver perchlorate afforded the pentaphenylTelluronium salt, Ph5Te+ClO, (1b), and treatment of 2 with silver triflate and sodium tetrakis{3,5-bis(trifluoromethyl)phenyl}borate provided Ph5Te+[3,5-(CF3)2C6H3]4B− (1c), which were isolated as stable yellow solids. X-ray crystallographic analyses of the hypervalent Telluronium salts revealed square-pyramidal geometry around the tellurium, which are rare examples for penta-substituted main group element compounds. © 2001 John Wiley & Sons, Inc. Heteroatom Chem 12:380–384, 2001
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synthesis and structure of pentaphenyl Telluronium salts of perchlorate and tetrakis 3 5 bis trifluoromethyl phenyl borate hypervalent onium compounds
Heteroatom Chemistry, 2001Co-Authors: Mao Minoura, Takahiro Mukuda, Takao Sagami, Kin-ya AkibaAbstract:The reaction of pentaphenyltellurium chloride 2 with silver perchlorate afforded the pentaphenylTelluronium salt, Ph5Te+ClO, (1b), and treatment of 2 with silver triflate and sodium tetrakis{3,5-bis(trifluoromethyl)phenyl}borate provided Ph5Te+[3,5-(CF3)2C6H3]4B− (1c), which were isolated as stable yellow solids. X-ray crystallographic analyses of the hypervalent Telluronium salts revealed square-pyramidal geometry around the tellurium, which are rare examples for penta-substituted main group element compounds. © 2001 John Wiley & Sons, Inc. Heteroatom Chem 12:380–384, 2001
