Copper-catalyzed coupling reaction of terminal alkynes with aryl- and alkenyliodonium salts

[reaction: see text]. The copper iodide-catalyzed cross-coupling of terminal alkynes with hypervalent iodonium salts was accomplished with CuI (10 mol %) and NaHCO3 (2 equiv) in DME/H2O (4:1) at room temperature for 30 min to afford arylalkynes or enynes under mild conditions.     

Nickel‐catalyzed three‐component coupling reaction of terminal alkynes,dihalomethane and amines to propargylamines

Direct C―H and C―halogen activation is an important and practical task in C―C, C―N bond formation reactions using alkynes. Propargylic amines are synthetically versatile intermediates for the preparation of many nitrogen‐containing biologically active motifs. Herein, a 15 mol% Ni(py)₄Cl₂/bipyridine‐catalyzed three‐component coupling reaction of alkynes, halomethane and amines through C―H and C―halogen activation was developed for the facile synthesis of propargylic amines. Tetramethylguanidine shows excellent basicity in acetonitrile and works under mild conditions. The reaction has very good functional group tolerance to aliphatic and aromatic alkynes. Copyright © 2013 John Wiley & Sons, Ltd.     

An efficient and facile one-pot synthesis of propargylamines by three-component coupling of aldehydes, amines, and alkynes via C-H activation catalyzed by NiCl2

NiCl₂ was found to be a highly efficient and effective catalyst for the one-pot three-component (A³) coupling of aldehydes, amines, and alkynes to produce propargylamines in nearly quantitative yields. Structurally divergent aldehydes, amines, and alkynes were converted into the corresponding propargylamines. No co-catalyst or activator is needed and water is the only byproduct of this novel protocol.     

Propargylic amines constructed via copper-catalyzed three-component coupling of terminal alkynes, benzal halides and amines

A method for the synthesis of propargylic amines has been developed via an efficient copper(I)-catalyzed three-component coupling reaction of alkynes, benzal halides and amines through C-H and C-halogen activation. This reaction is conducted under mild conditions and provides an alternative method for the synthesis of propargylic amines.     

Syntheses of N-sulfonyl-N,N-disubstituted amidines via a three-component free-radical coupling reaction of tertiary amines and arenesulfonyl azides with terminal alkynes

A facile and efficient synthesis of N-sulfonyl-N,N-disubstituted amidines has been achieved via a CuI-catalyzed three-component free-radical coupling reaction of tertiary amines and arenesulfonyl azides with terminal alkynes in the presence of azodiisobutyronitrile(AIBN).The reaction mechanism of this reaction has also been studied.     

Palladium catalyzed alkylation of indole via aliphatic C-H bond activation of tertiary amine

Alkylation of indoles has been achieved via Pd-catalyzed aliphatic C-H bond activation of tertiary amine coupling with indole followed by C-N bond cleavage and subsequent addition of indole. This method involves the migration of alkane chain from tertiary amine to indole.     

Copper-catalyzed trifluoromethylation of terminal alkenes through allylic C-H bond activation

An unprecedented type of reaction for Cu-catalyzed trifluoromethylation of terminal alkenes is reported. This reaction represents a rare instance of catalytic trifluoromethylation through C(sp(3))-H activation. It also provides a mechanistically unique example of Cu-catalyzed allylic C-H activation/functionalization. Both experimental and theoretical analyses indicate that the trifluoromethylation may occur via a Heck-like four-membered-ring transition state.     

Copper-catalyzed three-component coupling of arynes, terminal alkynes and activated alkenes

The three-component coupling of benzynes with terminal alkynes and activated alkenes in the presence of CuI, PCy(3) and CsF in a 1:1 mixture of CH(3)CN and THF at 50 degrees C for 5 h gave 1-alkyl-2-alkynylbenzenes in good to moderate yields.     

Copper-catalyzed cross dehydrogenative coupling reactions of tertiary amines with ketones or indoles

A novel cross dehydrogenative coupling (CDC) reaction of N,N-dimethylanilines with methyl ketones by cooperative copper and aminocatalysis has been developed, which leads to the formation of β-arylamino ketones in 42-73% yields. Moreover, the copper-catalyzed alkylation of free (NH) indoles with N,N-dimethylanilines via CDC reaction is also presented, affording alkylated indoles in 52-78% yields.     

基于C-H键活化的铜催化二苄胺氧化酰胺化反应

基于铜催化的C-H键活化构建了一类高效的二苄胺氧化酰基化生成N-苄基苯甲酰胺的反应. 该反应使用CuBr作为催化剂, 二乙酸碘苯作为氧化剂, 在温和条件下生成两种酰胺, 总产率最高可达92.0%. CuBr催化剂价廉易得, 催化活性高. 同时这也是首次使用二乙酸碘苯作为氧化剂, 通过二苄胺的直接氧化酰基化反应合成N-苄基苯甲酰胺.     

Copper-catalyzed oxidative amination of benzoxazoles via C-H and C-N bond activation: a new strategy for using tertiary amines as nitrogen group sources

An efficient and conceptually new method for oxidative amination of azoles with tertiary amines via copper-catalyzed C-H and C-N bond activation has been developed. This protocol can be performed in the absence of external base and only requires atmospheric oxygen as oxidant. The catalyst system is very simple and efficient, which opens a new way for using tertiary amines as nitrogen group sources for C-N bond formation reactions.     

Synthesis of indoles via palladium-catalyzed C-H activation of N-aryl amides followed by coupling with alkynes

A convenient and efficient method for the construction of indole skeleton was developed via Pd-catalyzed C-H activation of N-aryl amides and subsequent coupling with alkynes. Both stoichiometric and catalytic versions have been successfully achieved.     

Copper-catalyzed direct cyanation of terminal alkynes with benzoyl cyanide

Copper-catalyzed direct cyanation of terminal alkynes is achieved using less toxic, stable and easy to handle benzoyl cyanide as a cyanide source and air as an oxidant. This protocol provides a good alternative to the preparation of 3-arylpropiolonitriles under mild condition.     

Copper-catalyzed coupling of aryl iodides with aliphatic alcohols

[reaction: see text] A simple and mild method for the coupling of aryl iodides and aliphatic alcohols that does not require the use of alkoxide bases is described. The reactions can be performed in neat alcohol. For more precious alcohols, the etherification was carried out in toluene as solvent using 2 equiv of alcohol. Additionally, the cross-coupling of an optically active benzylic alcohol with an unactivated aryl halide was demonstrated to proceed with complete retention of configuration.     

From terminal alkynes directly to branched amines

The one-pot synthesis of several branched secondary aliphatic amines is described. Hydroamination of terminal alkynes with aliphatic primary amines in the presence of Cp₂Ti(η²-Me₃SiCCSiMe₃) gives the corresponding aldimines as intermediates. Reaction of these in situ produced aldimines with organolithium reagents (n-BuLi, PhLi) provides the α-branched amines in an easy way in upto 78% overall yield.     

Synthesis of fused polycycles from propargylic compounds with terminal alkynes via a palladium-catalyzed tandem C-H activation/biscyclization process

Various benzo[b]fluorene and fluorene derivatives have been prepared from propargylic compounds with terminal alkynes through a novel palladium-catalyzed tandem biscyclization reaction. This reaction involved a sequence of carboannulation, coupling, C-H activation and C-C bond formation process. A plausible mechanism has been proposed that was consistent with the deuterium-labeling experiment.     

Intermolecular coupling of alkenes to heterocycles via C-H bond activation

The intermolecular coupling of unactivated alkenes to a range of heterocycles using a Rh(I) catalyst was investigated. A variety of functional groups were incorporated into the alkene, including esters, nitriles, acetals, and phthalimide. Furthermore, the heterocycle tolerated substitution with both electron-rich and electron-deficient groups. The intermolecular coupling became possible after it was discovered that weak acids dramatically increase the rate of both the inter- and intramolecular reactions. An extensive optimization of additives was performed, and HCl.PCy(3) (Cy = cyclohexyl) and HCl.P-t-Bu(2)Et were in general found to be the best additives for the reaction.     

Synthesis of pyridines from ketoximes and terminal alkynes via C-H bond functionalization

An expedient one-pot rhodium catalyzed C-H bond functionalization/electrocyclization/dehydration procedure has been developed for the synthesis of highly substituted pyridine derivatives from terminal alkynes and α,β-unsaturated ketoximes. The use of electron-deficient phosphite ligands is important to suppress dimerization of the terminal alkynes to enynes.     

Copper-catalyzed aerobic oxidative coupling of terminal alkynes with α-carbonyl aldehydes: An expedient approach toward ynediones

An efficient and mild one-pot approach for copper-catalyzed aerobic oxidative coupling of α-carbonyl aldehydes with terminal alkynes toward ynediones has been developed. Moreover, a variety of ynediones were constructed under the optimized reaction conditions, and a plausible mechanism was presented based on a series of control experiments.     

Gold(III) (C^N) complex-catalyzed synthesis of propargylamines via a three-component coupling reaction of aldehydes, amines and alkynes

Propargylamines are synthesized in high yields via a gold(III) (C^N) complex-catalyzed three-component coupling reaction of aldehydes, amines and alkynes in water at 40 °C. Excellent diastereoselectivities (up to 99:1) have been achieved when chiral prolinol derivatives are employed as the amine component. Notably, the [Au(C^N)Cl₂] complex (N^CH = 2-phenylpyridine) could be repeatedly used for 10 reaction cycles, leading to an overall turnover number of 812.