Transformation Of Alkynes Research Articles

Isolation and characterization of gem-diaurated species having two C-Au σ bonds in gold(i)-activated amidiniumation of alkynes.

We have investigated the ligand effect on the gold-activated intramolecular amidiniumation of formamidine having a terminal alkyne, and observed the transformation of vinyl gold species into a gem-digold intermediate comprising two C-Au σ bonds, which represents a new binding mode for gem-digold species in the gold-promoted transformation of alkynes.

Cu-Catalyzed Transformation of Alkynes and Alkenes with Azide and Dimethyl Sulfoxide Reagents.

A novel and efficient Cu-catalyzed nitrogenation of alkynes and alkenes for the direct synthesis of sulfur-containing triazoles is described. Simple and readily available sulfoxides and azides are employed as the S- and N-source to prepare highly value N-,S-containing compounds from simple alkynes and alkenes.

ChemInform Abstract: Copper Nitrate Mediated Regioselective [2 + 2 + 1] Cyclization of Alkynes with Alkenes: A Cascade Approach to Δ2‐Isoxazolines.

AbstractThe regioselective synthesis of pharmacologically relevant polysubstituted Δ2—isoxazolines is based on the copper‐mediated direct transformation of terminal alkynes and alkenes.

Carboxylic Group-Assisted Proton Transfer in Gold-Mediated Thiolation of Alkynes

Combined experimental and theoretical studies revealed a complex mechanistic picture in which the carboxylic group-assisted proton transfer from acetic acid to an alkyne molecule is the key step in the unique gold-mediated alkyne transformation that leads to the formation of gem-disubstituted vinyl gold complexes. The structures of the complexes were unambiguously established using NMR spectroscopy (in solution) and X-ray diffraction (in the solid state). ESI-MS study of the reaction mixture revealed multiple gold-containing complexes and clusters. Investigation of the MS2 fragmentation patterns of the selected ions suggested the involvement of gold acetylides in the transformation. Further treatment of the complexes with protic acid led to the discovery of a novel route for the gold-mediated alkyne hydrothiolation.

Difluoromethylation of Terminal Alkynes by Fluoroform.

The difluoromethylation of terminal alkynes through the use of fluoroform as a source of difluorocarbene is described. The choice of solvents and bases was found to be crucial for the transformation. A series of terminal alkynes 1 were nicely converted into the corresponding difluoromethyl alkynes 2 using potassium tert-butoxide in n-decane in moderate to good yields. Functional groups such as methoxy, dimethylamino, and bromo as well as phenyl, heteroaryl, and sterically demanding naphthyl were well tolerated under the reaction conditions. One-step transformations of difluoromethyl alkynes 2 to difluoromethylated isoxazoles 3 and 1,2,3-triazoles 4 were also achieved.

Carbon nanofibers as supports for metal nanoparticles

The easy synthesis of transition metal nanoparticles supported on three types of carbon nanofibers (platelet: CNF-P, tubular: CNF-T, herringbone: CNF-H) and nitrogen-doped CNF-H (N-CNF-H) is accomplished by pyrolysis of metal carbonyl clusters such as Ru3(CO)12, Rh4(CO)12, and Ir4(CO)12, and alkene complexes such as Pd2(dba)3·CHCl3 and Pt(dba)2 [dba: dibenzylideneacetone]. Transmission electron microscopy of these CNFs with immobilized metal nanoparticles (M/CNFs and M/N-CNF-H) showed that metal nanoparticles whose size could be controlled, existed on the CNFs, and that their location was dependent on the surface nanostructure of the CNFs: on the edge of the graphite layers (CNF-P), in the tubes and on the surface (CNF-T), and between the layers and on the edge (CNF-H). Among these M/CNFs, Ru/CNF-P and Rh/CNF-T showed excellent catalytic activity towards arene hydrogenation with high reusability and functional group tolerance, while the Pt/CNF-P behaves as an efficient catalyst for the hydrogenation of substituted nitroarenes to the corresponding aniline derivatives with the other functional groups remaining intact. Pt and Pd nanoparticles supported on N-CNF-H act as poisoning catalysts for the transformation of internal alkynes to (Z)-alkenes over Pd/N-CNF-H, and for the transformation of nitroarenes to the corresponding anilines and N-hydroxylamines over Pt/N-CNF-H. [TANSO 2015 (No. 266) 35–40.]

Alkyne hydroacylation: switching regioselectivity by tandem ruthenium catalysis.

By using tandem Ru-catalysis, internal alkynes can be coupled with aldehydes for the synthesis of β,γ-unsaturated ketones. The catalyst promotes alkyne transformations with high regioselectivity, with examples that include the differentiation of a methyl vs ethyl substituent on the alkyne. Mechanistic studies suggest that the regioselectivity results from a selective allene formation that is governed by allylic strain.

Copper-catalyzed direct transformation of simple alkynes to alkenyl nitriles via aerobic oxidative N-incorporation.

A novel direct transformation of aliphatic terminal alkynes to alkenyl nitriles through the incorporation of a nitrogen atom into the simple hydrocarbons has been reported. The usage of inexpensive copper catalyst, O2 as the sole oxidant, broad substrate scope as well as feasibility for "late-stage modification" make this protocol very promising. Mechanistic studies including DFT calculation demonstrate a novel 1,2-hydride shift process for this novel nitrogenation reaction.

Rhodium-catalyzed denitrogenative thioacetalization of N-sulfonyl-1,2,3-triazoles with disulfides: an entry to diverse transformation of terminal alkynes.

An efficient and useful rhodium-catalyzed denitrogenative thioacetalization of N-sulfonyl-1,2,3-triazoles has been developed for the first time. The protocol uses readily available N-sulfonyl-1,2,3-triazoles and diaryl disulfides as the starting materials. The corresponding hydrolytic and reductive products with thioacetals were obtained in good to excellent yields, and the reactions were carried out easily under mild conditions with tolerance of some functional groups. Furthermore, the generated thioacetals could be transformed into some useful compounds. Therefore, the present method provides a novel and valuable strategy for the diverse transformation of alkynes.

ChemInform Abstract: A Salen—Co3+ Catalyst for the Hydration of Terminal Alkynes and in Tandem Catalysis with Ru—TsDPEN for the One‐Pot Transformation of Alkynes into Chiral Alcohols.

The cobalt–salen complex (C1:[(salen)Co3+(OAc)]; salen= N,N′-bis(salicylidene)ethylenediamine, OAc=acetate) was found to efficiently promote the hydration of terminal alkynes to give methyl ketones in the presence of the H2SO4 cocatalyst. In addition, the one-pot transformation of alkynes into chiral alcohols through tandem catalysis by catalyst C1 coupled with a ruthenium–TsDPEN complex (C3: [(R,R-TsDPEN)Ru2+(cymene)]; TsDPEN=(1R,2R)-N-(p-toluenesulfonyl)-1,2-diphenylethylenediamine, cymene=1-methyl-4-(1-methylethyl)benzene) catalyst was realized with excellent yields and enantioselectivities.

Direct transformation of terminal alkynes to branched allylic sulfones.

A new strategy for the transformation of terminal alkynes to branched allylic sulfones was developed. Using a Rh(I)/DPEphos/benzoic acid catalyst system, terminal alkynes react with sulfonyl hydrazides to produce branched allylic sulfones with good to excellent yields and selectivities in general.

ChemInform Abstract: Regioselective Transformation of Alkynes Catalyzed by a Copper Hydride or Boryl Copper Species

AbstractReview: 76 refs.

Ruthenium-catalyzed oxidative transformations of terminal alkynes to ketenes by using tethered sulfoxides: access to β-lactams and cyclobutanones.

The oxidation of in situ generated Ru vinylidenes to ketenes is realized with tethered sulfoxides. The result is a Ru-catalyzed oxidative transformation of terminal alkynes to highly valuable ketenes. Moreover, the ketenes generated here were shown to undergo characteristic ketene [2+2] cycloaddition reactions with tethered alkenes and external imines, yielding synthetically versatile bicyclic cyclobutanones and β-lactams, respectively.

A Salen–Co3+ Catalyst for the Hydration of Terminal Alkynes and in Tandem Catalysis with Ru–TsDPEN for the One‐Pot Transformation of Alkynes into Chiral Alcohols

AbstractThe cobalt–salen complex (C1:[(salen)Co3+(OAc)]; salen= N,N′‐bis(salicylidene)ethylenediamine, OAc=acetate) was found to efficiently promote the hydration of terminal alkynes to give methyl ketones in the presence of the H2SO4 cocatalyst. In addition, the one‐pot transformation of alkynes into chiral alcohols through tandem catalysis by catalyst C1 coupled with a ruthenium–TsDPEN complex (C3: [(R,R‐TsDPEN)Ru2+(cymene)]; TsDPEN=(1R,2R)‐N‐(p‐toluenesulfonyl)‐1,2‐diphenylethylenediamine, cymene=1‐methyl‐4‐(1‐methylethyl)benzene) catalyst was realized with excellent yields and enantioselectivities.

ChemInform Abstract: One‐Pot Transformation of Alkynes into Alcohols and Amines with Formic Acid.

AbstractThe reaction is conducted by means of pH‐regulated aqueous transfer hydrogenation.

ChemInform Abstract: Rhodium‐Catalyzed Oxygenative Addition to Terminal Alkynes for the Synthesis of Esters, Amides, and Carboxylic Acids.

AbstractThis is a versatile method for the direct transformation of terminal alkynes into various carboxylic acid derivatives.

Regioselective transformation of alkynes catalyzed by a copper hydride or boryl copper species

This review summarizes the transformation of alkynes using a copper hydride (Cu–H) or boryl copper (Cu–B) species as the active species. The semihydrogenation, hydrocarboxylation, and hydroboration of alkynes have been developed using Cu–H as the active species. The hydroboration, diboration, carboboration and boracarboxylation of alkynes involve the Cu–B species. These transformations afforded multi-substituted alkenes that are potentially good intermediates in organic synthesis. The key to the regioselective transformation is the addition of the Cu–H or Cu–B species to an alkyne, to afford the corresponding alkenylcopper intermediate regioselectively.

炭化水素からの直接ニトリル合成反応

The development of synthetic method of nitrile without metal cyanide is attracting much attention in synthetic organic chemistry because classical cyanation normally requires toxic metal cyanides and careful handling to prevent the generation of HCN gas. Recently, direct nitrogenation of hydrocarbons has been accomplished as a new approach to synthesize nitriles without metal cyanide. These approaches enable the straightforward utilization of hydrocarbons in organic synthesis. This short review focuses on the direct transformation of methyl arenes, alkynes, and alkenes by using appropriate oxidant and nitrogen sources.

ChemInform Abstract: The Indium‐Catalyzed Hydration of Alkynes Using Substoichiometric Amounts of PTSA as Additive.

AbstractA general, efficient, and highly regioselective protocol for the transformation of alkynes to the corresponding ketones is presented.

Cleavage of Carbon–Carbon Triple Bond: Direct Transformation of Alkynes to Nitriles

A new cleavage reaction of carbon-carbon triple bonds proceeds efficiently with NIS and TMSN3, giving the corresponding nitriles in moderate to good yields.