Non-activated Terminal Alkynes Research Articles

Enantio- and Regioselective Copper-Catalyzed 1,2-Dearomatization of Pyridines.

A copper-catalyzed dearomative alkynylation of pyridines is reported with excellent regio- and enantioselectivities. The synthetically valuable enantioenriched 2-alkynyl-1,2-dihydropyridine products afforded are generated from the readily available feedstock, pyridine, and commercially available terminal alkynes. The three-component reaction between a pyridine, a terminal alkyne, and methyl chloroformate employs copper chloride and StackPhos, a chiral biaryl P,N- ligand, as the catalytic system. Under mild reaction conditions, the desired 1,2-addition products are delivered in up to 99 % yield with regioselectivity ratios up to 25 : 1 and enantioselectivities values of up to 99 % ee. Activated and non-activated terminal alkynes containing a wide range of functional groups are well tolerated. Even acetylene gas delivered mono-alkynylated products in high yield and ee. Application of the methodology in an efficient enantioselective synthesis of the chiral piperidine indolizidine, coniceine, is reported.

Regio- and Chemoselective Copper-Catalyzed Formal [2+2+2] Cycloaddition of Primary Amines with Arylacetylenes to 2,4,5-Trisubstituted Pyridines.

Disclosed herein is an efficient strategy for the synthesis of 2,4,5-trisubstituted pyridines via CuI/NBS-catalyzed formal intermolecular [2+2+2] cycloaddition of easily available primary amines and nonactivated terminal alkynes. Moreover, this given reaction features a new mode of cycloaddition with high regio- and chemoselectivity, good atom- and step-economy, broad substrate scope, and wide functional group compatibility. Further mechanism studies indicate that this transformation starts with oxidative alkynylation of the amine to form a propargylamine intermediate, followed by radical addition to the alkyne and intramolecular cycloaddition, delivering the pharmacologically interesting multisubstituted pyridines.

Rhodium-Catalyzed Chemo- and Regioselective Intermolecular Cross-Cyclotrimerization of Nonactivated Terminal and Internal Alkynes.

It has been established that a cationic rhodium(I)/BIPHEP complex is able to catalyze the unprecedented intermolecular cross-cyclotrimerization of nonactivated terminal and internal alkynes at room temperature. In this transformation, the use of arylacetylenes as terminal alkynes and 1,4-butynediol derivatives as internal alkynes afforded the cross-cyclotrimerization products with good chemo- and regioselectivity. The present study clearly demonstrated that an electronically biased combination of nonactivated and electron-deficient alkynes is not necessary to realize good chemo- and regioselectivity in the cationic rhodium(I) complex-catalyzed intermolecular cross-cyclotrimerization.

Trifluoroethanol as an efficient reaction media for the synthesis of pyran skeleton through domino Knoevenagel–hetero-Diels–Alder reaction with non-activated alkynes

Trifluoroethanol as an efficient media for the domino Knoevenagel–hetero-Diels–Alder reaction of O-propargyloxy benzaldehydes as non-activated terminal alkynes with some active methylene compounds has been described. Short reaction time, easy work-up, good to high yields, and mild reaction conditions are advantages of this new media.

An efficient catalytic system based on 7,8-dihydroxy-4-methylcoumarin and copper(II) for the click synthesis of diverse 1,4-disubstituted-1,2,3-triazoles under green conditions.

In this work, the combination of 7,8-dihydroxy-4-methyl coumarin (DHMC) as a novel bidentate O,O-chelating agent and copper(II) acetate monohydrate (2:1 molar ratio) has been found to form an efficient catalytic system. This catalyst provided good to excellent yields in the multi-component click synthesis of 1,4-disubstituted-1,2,3-triazoles by using various structurally diverse organic halides, different non-activated terminal alkynes, and sodium azide. This catalytic system eliminates the need for the isolation of the hazardous azide intermediates which are generated in situ. The reaction is carried out in aqueous phase at room temperature and it can be accelerated by sonication or by increasing the reaction temperature. Moreover, the reaction can be performed in large scale. It is noteworthy that DHMC is commercially available and that it can be easily synthesized with low cost materials.

Mild chemo-selective hydration of terminal alkynes catalysed by AgSbF6

The chemo-selective hydration of a wide range of non-activated terminal alkynes catalysed by AgSbF(6) under mild conditions is reported.

Iridium complex-catalyzed addition of water and alcohols to non-activated terminal alkynes

The addition of water and alcohols to non-activated terminal alkynes was found to be promoted by an iridium complex combined with Lewis acid and phosphite. Thus, terminal alkynes reacted with water or alcohols to give ketones or ketals, respectively, in good to excellent yields. α,ω-Diyne like 1,7-octadiyne was converted into 1-(2-methyl-cyclopent-1-enyl)ethanone through the intramoleculer aldol condensation of the resulting 2,7-octanedione induced by Lewis acid.

Copper‐Catalyzed Synthesis of N‐Unsubstituted 1,2,3‐Triazoles from Nonactivated Terminal Alkynes.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Copper‐Catalyzed Synthesis of N‐Unsubstituted 1,2,3‐Triazoles from Nonactivated Terminal Alkynes

AbstractThe [3+2] cycloaddition of nonactivated terminal alkynes and trimethylsilyl azide proceeded smoothly in the presence of CuI catalyst and DMF/MeOH, to give the corresponding N‐unsubstituted triazoles in good to high yields. The reaction most probably proceeds through the in situ formation of a copper acetylide species and hydrazoic acid, followed by a successive [3+2] cycloaddition reaction. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)

A One-Pot Procedure for the Regiocontrolled Synthesis of Allyltriazoles via the Pd—Cu Bimetallic Catalyzed Three-Component Coupling Reaction of Nonactivated Terminal Alkynes, Allyl Carbonate, and Trimethylsilyl Azide.

A one-pot procedure for the regiocontrolled synthesis of both 2-allyl- and 1-allyl-1,2,3-triazoles via the three-component coupling (TCC) reaction between nonactivated terminal alkynes, allyl carbonate, and trimethylsilyl azide (TMSN3) under a palladium and copper bimetallic catalyst has been developed. To accomplish the regioselective synthesis of the allyltriazoles, proper choice of two different catalyst systems is needed. The combination of Pd2(dba)3·CHCl3−CuCl(PPh3)3−P(OPh)3 catalyzes the formation of 2-allyl-1,2,3-triazoles, while the combination of Pd(OAc)2−CuBr2−PPh3 promotes the formation of 1-allyl-1,2,3-triazoles. The cooperative activity of palladium and copper catalysts plays an important role in the present transformations. Most probably, the palladium catalyst works as a catalyst for generating reactive azide species, π-allylpalladium azide complex and allyl azide. The copper catalyst probably behaves as an activator of the C−C triple bond of the starting terminal alkynes by forming a coppe...

A One-Pot Procedure for the Regiocontrolled Synthesis of Allyltriazoles via the Pd−Cu Bimetallic Catalyzed Three-Component Coupling Reaction of Nonactivated Terminal Alkynes, Allyl Carbonate, and Trimethylsilyl Azide

A one-pot procedure for the regiocontrolled synthesis of both 2-allyl- and 1-allyl-1,2,3-triazoles via the three-component coupling (TCC) reaction between nonactivated terminal alkynes, allyl carbonate, and trimethylsilyl azide (TMSN(3)) under a palladium and copper bimetallic catalyst has been developed. To accomplish the regioselective synthesis of the allyltriazoles, proper choice of two different catalyst systems is needed. The combination of Pd(2)(dba)(3).CHCl(3)-CuCl(PPh(3))(3)-P(OPh)(3) catalyzes the formation of 2-allyl-1,2,3-triazoles, while the combination of Pd(OAc)(2)-CuBr(2)-PPh(3) promotes the formation of 1-allyl-1,2,3-triazoles. The cooperative activity of palladium and copper catalysts plays an important role in the present transformations. Most probably, the palladium catalyst works as a catalyst for generating reactive azide species, pi-allylpalladium azide complex and allyl azide. The copper catalyst probably behaves as an activator of the C-C triple bond of the starting terminal alkynes by forming a copper-acetylide intermediate and thereby promotes the [3 + 2]-cycloaddition reaction between the reactive azide species and the copper-acetylide to form the triazole framework.

Synthesis of Triazoles from Nonactivated Terminal Alkynes via the Three‐Component Coupling Reaction Using a Pd(0)—Cu(I) Bimetallic Catalyst.

ChemInformVolume 34, Issue 43 Heterocyclic Compounds Synthesis of Triazoles from Nonactivated Terminal Alkynes via the Three-Component Coupling Reaction Using a Pd(0)—Cu(I) Bimetallic Catalyst. Shin Kamijo, Dep. Chem., Grad. Sch. Sci., Tohoku Univ., Aoba, Sendai 980, JapanSearch for more papers by this authorTienan Jin, Dep. Chem., Grad. Sch. Sci., Tohoku Univ., Aoba, Sendai 980, JapanSearch for more papers by this authorZhibao Huo, Dep. Chem., Grad. Sch. Sci., Tohoku Univ., Aoba, Sendai 980, JapanSearch for more papers by this authorYoshinori Yamamoto, Dep. Chem., Grad. Sch. Sci., Tohoku Univ., Aoba, Sendai 980, JapanSearch for more papers by this author Shin Kamijo, Dep. Chem., Grad. Sch. Sci., Tohoku Univ., Aoba, Sendai 980, JapanSearch for more papers by this authorTienan Jin, Dep. Chem., Grad. Sch. Sci., Tohoku Univ., Aoba, Sendai 980, JapanSearch for more papers by this authorZhibao Huo, Dep. Chem., Grad. Sch. Sci., Tohoku Univ., Aoba, Sendai 980, JapanSearch for more papers by this authorYoshinori Yamamoto, Dep. Chem., Grad. Sch. Sci., Tohoku Univ., Aoba, Sendai 980, JapanSearch for more papers by this author First published: 30 September 2003 https://doi.org/10.1002/chin.200343114Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onEmailFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume34, Issue43October 28, 2003 RelatedInformation

Synthesis of triazoles from nonactivated terminal alkynes via the three-component coupling reaction using a Pd(0)-Cu(I) bimetallic catalyst.

The synthesis of triazoles via the three-component coupling reaction of unactivated terminal alkynes, allyl carbonate, and trimethylsiyl azide under the Pd(0)-Cu(I) bimetallic catalyst is developed. The reaction most probably proceeds through the formation of a pi-allylpalladium azide complex and a copper-acetylide followed by a successive [3 + 2] cycloaddition. The deallylation of the resulting allyltriazoles proceeds very easily by the Ru-catalyzed isomerization followed by the ozonolysis of the resulting propenyltriazoles to give the triazoles in high yields.

Palladium-catalysed mild transformation of non-activated terminal alkynes into acetals

Pd(pp2) (O3SCF3)2 (pp2 = bis(2-diphenylphosphinoethyl)phenylphosphine) catalyses the transformation of non-activated terminal alkynes into acetals. The reaction proceeds fast, without the addition of heat and in quantitative yield. σ-Alkynyl-palladium complexes have been identified as intermediates.

Ruthenium complex-catalysed addition of N-aryl substituted amides to alkynes: novel synthesis of enamides

The addition of N-aryl substituted amides to non-activated terminal alkynes is efficiently promoted by the Ru3(CO)12–PCy3 catalyst system, affording the corresponding linear (E)-enamides in good yields with high regio- and stereo-selectivity.