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Yuefei Hu - One of the best experts on this subject based on the ideXlab platform.
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enantiopure 2 6 disubstituted piperidines bearing one alkene or Alkyne containing substituent preparation and application to total syntheses of indolizidine alkaloids
ChemInform, 2010Co-Authors: Deyong Su, Guolin Cheng, Jimin Xu, Xinyan Wang, Yuefei HuAbstract:Starting with the known precursor (I), a library of 18 optically active 2,6-disubstituted piperidines such as (VI) carrying one alkene or Alkyne moiety is prepared.
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enantiopure 2 6 disubstituted piperidines bearing one alkene or Alkyne containing substituent preparation and application to total syntheses of indolizidine alkaloids
Organic and Biomolecular Chemistry, 2010Co-Authors: Deyong Su, Guolin Cheng, Jimin Xu, Xinyan Wang, Yuefei HuAbstract:A general and efficient procedure for the preparation of 2,6-disubstituted piperidines bearing one alkene- or Alkyne-containing substituent was developed by using non-racemic Betti base as a chiral auxiliary. Many chiral benzylamines are excellent auxiliaries, but they were rarely used for this purpose because of the inefficient removal of the N-benzyl auxiliary residue under non-hydrogenative conditions. We found that N,N-disubstituted Betti base derivative has a typical Mannich structure of o-naphthol. When it carried out a base-catalyzed formation of o-quinone methide, an efficient non-hydrogenative N-debenzylation was achieved, and the alkene and Alkyne groups survived. To demonstrate the efficiency of the method and the versatility of the products, asymmetric total syntheses of indolizidine-alkaloids (−)-167B, (−)-195H, (−)-209D and (−)-223AB were accomplished.
Antonio M Echavarren - One of the best experts on this subject based on the ideXlab platform.
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gold i catalyzed activation of Alkynes for the construction of molecular complexity
Chemical Reviews, 2015Co-Authors: Ruth Dorel, Antonio M EchavarrenAbstract:1.1. General Reactivity of Alkyne-Gold(I) Complexes For centuries, gold had been considered a precious, purely decorative inert metal. It was not until 1986 that Ito and Hayashi described the first application of gold(I) in homogeneous catalysis.1 More than one decade later, the first examples of gold(I) activation of Alkynes were reported by Teles2 and Tanaka,3 revealing the potential of gold(I) in organic synthesis. Now, gold(I) complexes are the most effective catalysts for the electrophilic activation of Alkynes under homogeneous conditions, and a broad range of versatile synthetic tools have been developed for the construction of carbon–carbon or carbon–heteroatom bonds. Gold(I) complexes selectively activate π-bonds of Alkynes in complex molecular settings,4−10 which has been attributed to relativistic effects.11−13 In general, no other electrophilic late transition metal shows the breadth of synthetic applications of homogeneous gold(I) catalysts, although in occasions less Lewis acidic Pt(II) or Ag(I) complexes can be used as an alternative,9,10,14,15 particularly in the context of the activation of alkenes.16,17 Highly electrophilic Ga(III)18−22 and In(III)23,24 salts can also be used as catalysts, although often higher catalyst loadings are required. In general, the nucleophilic Markovnikov attack to η2-[AuL]+-activated Alkynes 1 forms trans-alkenyl-gold complexes 2 as intermediates (Scheme 1).4,5a,9,10,12,25−29 This activation mode also occurs in gold-catalyzed cycloisomerizations of 1,n-enynes and in hydroarylation reactions, in which the alkene or the arene act as the nucleophile. Scheme 1 Anti-Nucleophilic Attack to η2-[AuL]+-Activated Alkynes
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gold catalyzed synthesis of tetrazoles from Alkynes by c c bond cleavage
Angewandte Chemie, 2013Co-Authors: Morgane Gaydou, Antonio M EchavarrenAbstract:Cycloadditions of azides with Alkynes to form triazoles under thermal conditions (Huisgen cycloaddition)[1] or in the presence of copper [click reaction, copper-catalyzed azide–Alkyne cycloaddition (CuAAC)][2,3] are reactions of fundamental importance in organic chemistry. Triazoles can also be obtained by means of ruthenium,[4] silver,[5] and iridium[6] catalysis, as well as by a zinc-mediated process.[7] In sharp contrast, very different reactivity has been observed in the reaction of terminal Alkynes with TMSN3 in the presence of group 11 metal salts and complexes.[8] Thus, the group of Jiao recently made the remarkable observation that Alkynes (1; R=alkyl, aryl, alkenyl) react with TMSN3 in the presence of Ag2CO3 as catalyst to form nitriles (2; Scheme 1).[9] The same group has reported the cleavage of the aryl–Alkyne C(sp2)=C(sp) bond of Alkynes (1) using [Au(PPh3)Cl] and AgCO3 in the presence of H2O and trifluoroacetic acid (TFA) to form carboxamides.[10]
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PtII catalyzed intramolecular reaction of furans with Alkynes
Angewandte Chemie - International Edition, 2001Co-Authors: Belén Martín-matute, Diego J Cardenas, Antonio M EchavarrenAbstract:The intramol. reactions of furans with Alkynes catalyzed by PtCl2 was studied . Using DFT, several pathways can be predicted in principle, starting with the coordination of the Alkyne to the metal center. The mechanism involved first, the Diels-Alder reaction between the furan and the coordinated Alkyne could give intermediate, second the formation of a cyclopropyl Pt carbene by the reaction of the Alkyne with the C2-C3 double bond of furan could occur. The third mechanism involved Friedel-Crafts-type reaction of the electron-deficient Alkyne at C2 of the furan. Results showed that the intramol. reaction of furans with Alkynes catalyzed by PtCl2 was mechanistically related to the enzymes in the polar solvents and was initiated by the nucleophilic attack of the furan on an η 2-Alkyne platinum complex to form a cyclopropyl platinum carbene. [on SciFinder(R)]
Deyong Su - One of the best experts on this subject based on the ideXlab platform.
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enantiopure 2 6 disubstituted piperidines bearing one alkene or Alkyne containing substituent preparation and application to total syntheses of indolizidine alkaloids
ChemInform, 2010Co-Authors: Deyong Su, Guolin Cheng, Jimin Xu, Xinyan Wang, Yuefei HuAbstract:Starting with the known precursor (I), a library of 18 optically active 2,6-disubstituted piperidines such as (VI) carrying one alkene or Alkyne moiety is prepared.
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enantiopure 2 6 disubstituted piperidines bearing one alkene or Alkyne containing substituent preparation and application to total syntheses of indolizidine alkaloids
Organic and Biomolecular Chemistry, 2010Co-Authors: Deyong Su, Guolin Cheng, Jimin Xu, Xinyan Wang, Yuefei HuAbstract:A general and efficient procedure for the preparation of 2,6-disubstituted piperidines bearing one alkene- or Alkyne-containing substituent was developed by using non-racemic Betti base as a chiral auxiliary. Many chiral benzylamines are excellent auxiliaries, but they were rarely used for this purpose because of the inefficient removal of the N-benzyl auxiliary residue under non-hydrogenative conditions. We found that N,N-disubstituted Betti base derivative has a typical Mannich structure of o-naphthol. When it carried out a base-catalyzed formation of o-quinone methide, an efficient non-hydrogenative N-debenzylation was achieved, and the alkene and Alkyne groups survived. To demonstrate the efficiency of the method and the versatility of the products, asymmetric total syntheses of indolizidine-alkaloids (−)-167B, (−)-195H, (−)-209D and (−)-223AB were accomplished.
Barry M. Trost - One of the best experts on this subject based on the ideXlab platform.
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Ruthenium-catalysed multicomponent synthesis of the 1,3-dienyl-6-oxy polyketide motif
Nature Chemistry, 2020Co-Authors: Barry M. Trost, James J. Cregg, Christoph Hohn, Guoting Zhang, Jacob S. TracyAbstract:Polyketide natural products are an important class of biologically active compounds. Although substantial progress has been made on the synthesis of repetitive polyketide motifs through the iterative application of a single reaction type, synthetic access to more diverse motifs that require more than one type of carbon–carbon bond connection remains a challenge. Here we describe a catalytic, multicomponent method for the synthesis of the privileged polyketide 1,3-dienyl-6-oxy motif. The method allows for the formation of two new carbon–carbon bonds and two stereodefined olefins. It generates products that contain up to three contiguous sp ^3 stereocentres with a high stereoselectivity in a single operation and can be used to generate chiral products. The successful development of this methodology relies on the remarkable efficiency of the ruthenium-catalysed alkene–Alkyne coupling reaction between readily available vinyl boronic acids and Alkynes to provide unsymmetrical 3-boryl-1,4-diene reagents. In the presence of carbonyl compounds, these reagents undergo highly diastereoselective allylations to afford the desired 1,3-dienyl-6-oxy motif and enable complex polyketide synthesis in a rapid and asymmetric fashion. A ruthenium-catalysed multicomponent reaction provides rapid and tunable access to 1,3-dienyl-6-oxy polyketide motifs. An initial alkene–Alkyne coupling produces unsymmetrical 3-boryl-1,4-dienes. Allylation of aldehydes and ketones with these products is highly diastereoselective and results in the formation of two carbon–carbon bonds, two stereodefined olefins and up to three contiguous sp ^3 stereocentres.
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stereocontrolled synthesis of vinyl boronates and vinyl silanes via atom economical ruthenium catalyzed alkene Alkyne coupling
Angewandte Chemie, 2015Co-Authors: Barry M. Trost, Dennis C Koester, Alastair N HerronAbstract:The synthesis of vinyl boronates and vinyl silanes was achieved by employing a Ru-catalyzed alkene–Alkyne coupling reaction of allyl boronates or allyl silanes with various Alkynes. The double bond geometry in the generated vinyl boronates can be remotely controlled by the juxtaposing boron- and silicon groups on the Alkyne substrate. The synthetic utility of the coupling products has been demonstrated in a variety of synthetic transformations, including iterative cross-coupling reactions, and a Chan-Lam-type allyloxylation followed by a Claisen rearrangement. A sequential one-pot alkene-Alkyne-coupling/allylation-sequence with an aldehyde to deliver a highly complex α-silyl-β-hydroxy olefin with a handle for further functionalization was also realized.
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ruthenium catalyzed alkene Alkyne coupling of disubstituted olefins application to the stereoselective synthesis of trisubstituted enecarbamates
Journal of the American Chemical Society, 2015Co-Authors: Barry M. Trost, James J. CreggAbstract:The Ru-catalyzed alkene–Alkyne coupling reaction has been demonstrated to be an enabling methodology for the synthesis of complex molecules. However, to date, it has been limited to monosubstituted olefins. Herein we report the first general utilization of disubstituted olefins in the Ru-catalyzed alkene–Alkyne coupling reaction by employing carbamate directing groups. The products are stereodefined trisusbstituted enecarbamates. The elaboration of these structures toward the asymmetric synthesis of complex aminocyclopentitols and 1,2-amino alcohols is discussed.
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Modern Alkyne Chemistry: Catalytic and Atom-Economic Transformations - Modern Alkyne chemistry : catalytic and atom-economic transformations
2014Co-Authors: Barry M. Trost, Chao-jun LiAbstract:Introduction PART I: CATALYTIC ISOMERIZATION OF AlkyneS 1) Redox Isomerization of Propargyl Alcohols to Enones 2) Carbophilic Cycloisomerization Reactions of Enynes and Domino Processes 3) Alkyne-Alkyne Metathesis Reactions PART II: CATALYTIC CYCLOADDITION REACTIONS 4) Alkyne-Azide Reactions 5) Catalytic Cycloaddition Reactions PART III: CATALYTIC NUCLEOPHILIC ADDITIONS AND SUBSTITUTIONS 6) Catalytic Conjugate Additions of Alkynes 7) Catalytic Alkyne-Carbonyl Additions 8) Catalytic Nucleophilic Addition of Alkynes to Imines: The A3 (Aldehyde-Alkyne-Amine) Coupling 9) Sonogashira Reactions PART IV: OTHER REACTIONS 10) Catalytic Dimerization of Alkynes 11) The Oxidative Dimerization of Acetylenes and Related Reactions: Synthesis and Applications of Conjugated 1,3-Diynes 12) The Alkyne Zipper Reaction in Asymmetric Synthesis
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Alkyne hydrosilylation catalyzed by a cationic ruthenium complex efficient and general trans addition
Journal of the American Chemical Society, 2005Co-Authors: Barry M. Trost, Zachary T BallAbstract:The complex [Cp*Ru(MeCN)3]PF6 is shown to catalyze the hydrosilylation of a wide range of Alkynes. Terminal Alkynes afford access to α-vinylsilane products with good regioselectivity. Deuterium labeling studies indicate a clean trans addition process is at work. The same complex is active in internal Alkyne hydrosilylation, where absolute selectivity for the trans addition process is maintained. Several internal Alkyne substrate classes, including propargylic alcohols and α,β-alkynyl carbonyl compounds, allow regioselective vinylsilane formation. The tolerance of a wide range of silanes is noteworthy, including alkyl-, aryl-, alkoxy-, and halosilanes. This advantage is demonstrated in the direct synthesis of triene substrates for silicon-tethered intramolecular Diels−Alder cycloadditions.
Xinyan Wang - One of the best experts on this subject based on the ideXlab platform.
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enantiopure 2 6 disubstituted piperidines bearing one alkene or Alkyne containing substituent preparation and application to total syntheses of indolizidine alkaloids
ChemInform, 2010Co-Authors: Deyong Su, Guolin Cheng, Jimin Xu, Xinyan Wang, Yuefei HuAbstract:Starting with the known precursor (I), a library of 18 optically active 2,6-disubstituted piperidines such as (VI) carrying one alkene or Alkyne moiety is prepared.
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enantiopure 2 6 disubstituted piperidines bearing one alkene or Alkyne containing substituent preparation and application to total syntheses of indolizidine alkaloids
Organic and Biomolecular Chemistry, 2010Co-Authors: Deyong Su, Guolin Cheng, Jimin Xu, Xinyan Wang, Yuefei HuAbstract:A general and efficient procedure for the preparation of 2,6-disubstituted piperidines bearing one alkene- or Alkyne-containing substituent was developed by using non-racemic Betti base as a chiral auxiliary. Many chiral benzylamines are excellent auxiliaries, but they were rarely used for this purpose because of the inefficient removal of the N-benzyl auxiliary residue under non-hydrogenative conditions. We found that N,N-disubstituted Betti base derivative has a typical Mannich structure of o-naphthol. When it carried out a base-catalyzed formation of o-quinone methide, an efficient non-hydrogenative N-debenzylation was achieved, and the alkene and Alkyne groups survived. To demonstrate the efficiency of the method and the versatility of the products, asymmetric total syntheses of indolizidine-alkaloids (−)-167B, (−)-195H, (−)-209D and (−)-223AB were accomplished.
