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Showing 1 to 20 of 141 for “"alkynes"”.
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Ruthenium Hydride Catalyzed Silylvinylation of Alkynes
… ruthenium hydride catalyzed coupling of internal alkynes with subsequent insertion of olefin acceptors is described. This approach utilizes a vinyl silicon tether to provide complete regiocontrol, a stereoselective anti-exo-dig cyclization which affords a tetrasubstituted olefin with a new …
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Palladium catalysed oligomerization of 1-alkynes
The oligomerization of 1-pentyne using palladium acetyl acetonate catalyst with various solvents and ligands was investigated. An equimolar mixture of HOAc and Et N proved to be a superior solvent. The major product observed in most cases was the dimer, 6-methylene-nona-yne, although both cis and …
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Developing unstrained alkenes and alkynes for bioorthogonal chemistry
… extensively developed. Unstrained alkenes and alkynes, however, have not been well investigated as IEDDA handles. In general, unstrained dienophiles are more straightforward to synthesise compared with strained dienophiles, therefore they are more accessible to researchers. In addition, the …
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Selective, nickel-catalyzed carbon-carbon bond-forming reactions of alkynes
Catalytic addition reactions to alkynes are among the most useful and efficient methods for preparing diverse types of substituted olefins. Controlling both regioselectivity and (EIZ)- selectivity in such transformations presents a significant challenge. In reactions that also involve the creation …
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Regio- and Stereo- selective Methods for the Borylation of Substituted Alkynes
Organoboron derivatives represent an important class of compounds due to the versatility of the carbon-boron bond in a variety of chemical reactions. Boron-containing compounds have garnered increasing attention as synthetic intermediates and medicinal agents. Therefore, the introduction of …
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Early transition metal catalysts for the living polymerization of olefins and alkynes
Zirconium and Hafnium Ziegler-Natta catalysts containing the [(2,6- C12C6H3NCH2CH2)2NMe]2- ([ArciN2NMe]2') ligand were prepared and employed in the polymerization of 1-hexene. Hafnium Ziegler-Natta catalysts containing the [(2,6- X2C6H3NHCH2)2C(CH3)(2-C5H4N)] ([Arx2NPy]2-) (X = Cl or F) ligand were …
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Structure Sensitivity of Alkanes Hydrogenolysis and Alkynes Hydrogenation on Supported Ir Catalysts
In many catalytic systems, the activity and selectivity of supported metal catalysts or extended metal surface catalysts would be affected by the metal surface structure, and this phenomenon is called structure sensitivity. Generally, structure sensitivity is led by the change of geometric and …
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Synthesis of indoles via palladium-catalyzed annulation of aryl chlorides and internal alkynes
… reagents, o-chloroacetanilide and internal alkynes, is reported. The system is efficient in delivering 2,3-disubstituted indoles in good to excellent yield with a high level of regioselectivity in most cases. Alkynes with alkyl, aryl, alkenyl, and trialkylsilyl substituents are compatible …
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Exploring Enantioselective and Multicomponent One-Pot Reactions Utilizing Alkynes as Linchpins Toward Biologically Active Molecules
… and high energy starting materials like alkynes can afford reactive intermediates that can then undergo further transformations in one pot. The Diels-Alder (DA) reaction is a powerful synthetic tool that organic chemists have relied on for forming six-membered rings with good …
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The Application of the Titanium-Catalyzed Hydroamination of Alkynes toward the Synthesis of Benzylisoquinoline Derivatives
The enantioselective synthesis of (+)-(S)-laudanosine (101) and (–)-(S)-xylopinine (102) were achieved successfully in 7 steps from commercially available homoveratylamine (86) in 62% and 51% yield, respectively. The key intermediate aminoalkyne 123 was accessed easily by coupling aryl iodide 115 …
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Asymmetric nickel-catalyzed three-component assembly of allylic amines from alkynes, imines and organoboron reagents
… Allylic amines are assembled in one step from alkynes, imines, and organoboron reagents (boronic acids or boranes) using a catalyst derived from Ni(cod)2 and (c-CsH9)3P or (o-anisyl)3P. This catalytic, three-component process is tolerant of ketones, esters, and free hydroxyl groups; a degree of …
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Synthesis of polycyclic heteroaromatic compounds via the intramolecular [4+2] cycloaddition of conjugated hetarenynes and alkynes
… [4+2] cycloadditions of hetarenynes and alkynes as a method for the synthesis of polycyclic benzo[b]-fused five-membered heteroaromatic compounds. Only scattered reports of this transformation existed prior to our work and these were very limited in their scope. The research presented in …
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Diastereoselective nickel-catalyzed reductive coupling of alkynes and aldehydes and application towards the B-type amphidinolides
… nickel-catalyzed reductive coupling reactions of alkynes and aldehydes to the synthesis of complex natural product targets was explored. The "B-Type" amphidinolides were selected as ideal targets owing to their molecular complexity and the paucity of synthetically viable means for their total …
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Preparation of Substituted Enol Derivatives from Terminal Alkynes and Progress Toward the Total Synthesis of Nigricanoside A
… of alpha-branched aldehydes from terminal alkynes. Specifically, alkenyl alanes, derived from the methylalumination of alkynes, are shown to be efficiently oxygenated with peroxyzinc species. The resulting metallo-enolate may be trapped with benzoic anhydride, acetic anhydride, and TESOTf …
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Investigations into the Manipulation of 1,2,3-Triazoles and Towards an Asymmetric ‘Click’ Reaction of Meso Bis-Alkynes
… chapter centres on the development of meso bis-alkynes which were to be used in the evaluation of an asymmetric ‘click’ reaction. A number of synthetic approaches to these compounds are described, with most falling short of their final target compound, and either needing further work or a …
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Complexation, coupling, and cleavage of organonitriles, alkynes, dinitrogen, hydrostannanes or phosphines by three-coordinate molybdenum(III) complexes
Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Chemistry, February 2002.
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Enantioselective nickel-catalyzed reductive coupling reactions of alkynes and aldehydes. Synthesis of amphidinolides T1 and T4 via catalytic, stereoselective macrocyclizations
… Nickel-Catalyzed Reductive Couplings of Alkynes and Aldehydes Allylic alcohol synthesis via a nickel-catalyzed reductive coupling reaction of alkylsubstituted alkynes and aldehydes was studied for ligand effects with respect to the regioselectivity and enantioselectivity of the coupling …
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