Sonogashira-type Reaction Research Articles

Photoinduced copper catalyzed nitrogen-to-alkyl radical relay Sonogashira-type coupling of o-alkylbenzamides with alkynes.

This report describes a copper-catalyzed, photoinduced N-to-alkyl radical relay Sonogashira-type reactions at benzylic sites in o-alkylbenzamides with alkynes. The process employs an N-to-alkyl radical mechanism, initiated through the copper-catalyzed reductive generation of nitrogen radicals. Radical translocation is facilitated by a 1,5-hydrogen atom transfer (1,5-HAT), leading to the formation of translocated carbon radicals. These radicals are then subjected to copper-catalyzed alkynylation. The methodology exhibits broad sub-strate scope and applicability to the synthesis of complex natural products.

Convenient syntheses of phthalocyanine and tetrabenzotriazaporphyrin (TBTAP) mono-alkynes; unhindered building blocks for click chemistry and beyond

Unsymmetrical phthalocyanines and related macrocycles are often desirable for covalent construction or the self-assembly of more complex architectures. Terminal alkynes are versatile in this regard because they are amenable to cross-coupling via Sonogashira-type reactions, alkyne-alkyne coupling via Glaser-type couplings, and triazole formation via Click reaction with azides. Here we describe two complementary syntheses to conveniently add a single alkyne onto the phthalocyanine peripheral position and onto the meso-phenyl group of an (aryl)tetrabenzotriazaporphyrin, here providing a remote link point that is insulated from the macrocycle.

Discrimination of the mechanistic hypotheses for two- and three-component cross-coupling reactions by using mathematical modeling of the differential selectivity patterns

Distinguishing between several probable mechanistic hypotheses for complex catalytic reactions is a very complicated task. The main cause of such complication is the simultaneous realization of several consecutive-parallel processes under the reactions proceeding including side reactions with the participation of a catalyst. Under these circumstances, using kinetic studies of the reactions can provide unique possibilities to discriminate alternative mechanistic proposals. To achieve the goal, we offer to use the studies of the differential selectivity of such complex reactions by analysing possible correspondence of its patterns to different mathematical models describing alternative mechanistic hypotheses. Using this approach the fine mechanistic details of the catalytic cycles of two-component cross-coupling Suzuki-Miyaura and Mizoroki-Heck reactions as well as of three-component Sonogashira-type reaction coupling have been established.

Copper-catalyzed Csp-chalcogen bond formation: Versatile approach to N-(3-(organochalcogenyl)prop-2-yn-1-yl)amides

This work describes the copper-catalyzed Csp-chalcogen bond formation through cross-coupling reactions of propynylbenzamides and diorganyl dichalcogenides at room temperature, under open atmosphere. Generally, the reactions have proceeded very smoothly, affording the new class of organochalcogen-containing propynylbenzamides in good yields. Notably, this protocol showed to be tolerant to neutral, electron-donating and electron-withdrawing substituents present in both reaction substrates. In addition, the applicability of the carbon-chalcogen bond as a reactive site has been proved by successfully employment of the N-methyl-N-(3-(butylselanyl)prop-2-yn-1-yl)benzamide as a precursor in palladium-catalyzed Suzuki and Sonogashira type reactions.

Synthesis of [2]Catenanes by Intramolecular Sonogashira-Type Reaction.

The catalytic activity of macrocyclic phenanthroline-CuI complexes was utilized to synthesize [2]catenanes by intramolecular Sonogashira-type reaction. The high reactivity of the acyclic starting material was critical to synthesize the [2]catenane in acceptable yields. The relationship between the yield of the [2]catenane and the structure of the starting materials was disclosed.

Silica Microparticles Supported Gold and Copper Ferrite Nanoparticles: A Magnetically Recyclable Bimetallic Catalyst for Sonogashira Reaction

AbstractNovel silica supported gold and copper ferrite nanoparticles (NPs) have been synthesized, characterized and used as a separable dual catalyst in Sonogashira type reaction. These Au.CuFe2O4@Silica NPs show a high efficiency as catalyst in the alkynylation not only of aryl iodides but also aryl bromides. By using only 0.5 mol% loading and t‐BuOK as base in N,N‐dimethylacetamide as solvent, aryl iodides react at 115 ºC in 1 d, whereas for aryl bromides the cross‐coupling takes place at 130 ºC in 2 d. The catalyst can be successfully recycled using an external magnet for four consecutive runs.

A new synthesis of resveratrol

Resveratrol was synthesized in a 4-step synthesis using a simple Sonogashira type reaction with 93% yield using commercially available 3,5-dimethoxy-1-ethynyl-benzene and 4-iodoanisole, followed by reduction, isomerization, and deprotection and with an overall yield of 63%.

Gas-Phase Investigations on the Transmetalation Step in Sonogashira Reactions

The microscopic reverse of the transmetalation step in the Pd/M (M = Cu, Ag, Au) catalyzed Sonogashira-type reactions has been observed in the gas phase upon collision-induced dissociation (CID) of the heterobimetallic complexes. Measuring the activation energies by quantitative energy-resolved CID experiments provides an upper bound for the internal rearrangement energies. The potential-energy surface is investigated by density functional theory calculations and compared to the experimental values.

Cross-Couplings Using Aryl Ethers via C-O Bond Activation Enabled by Nickel Catalysts.

Arene synthesis has been revolutionized by the invention of catalytic cross-coupling reactions, wherein aryl halides can be coupled with organometallic and organic nucleophiles. Although the replacement of aryl halides with phenol derivatives would lead to more economical and ecological methods, success has been primarily limited to activated phenol derivatives such as triflates. Aryl ethers arguably represent one of the most ideal substrates in terms of availability, cost, safety, and atom efficiency. However, the robust nature of the C(aryl)-O bonds of aryl ethers renders it extremely difficult to use them in catalytic reactions among the phenol derivatives. In 1979, Wenkert reported a seminal work on the nickel-catalyzed cross-coupling of aryl ethers with Grignard reagents. However, it was not until 2004 that the unique ability of a low-valent nickel species to activate otherwise unreactive C(aryl)-O bonds was appreciated with Dankwardt's identification of the Ni(0)/PCy3 system, which significantly expanded the efficiency of the Wenkert reaction. Application of the nickel catalyst to cross-couplings with other nucleophiles was first accomplished in 2008 by our group using organoboron reagents. Later on, several other nucleophiles, including organozinc reagents, amines, hydrosilane, and hydrogen were shown to be coupled with aryl ethers under nickel catalysis. Despite these advances, progress in this field is relatively slow because of the low reactivity of benzene derivatives (e.g., anisole) compared with polyaromatic substrates (e.g., methoxynaphthalene), particularly when less reactive and synthetically useful nucleophiles are used. The "naphthalene problem" has been overcome by the use of N-heterocyclic carbene (NHC) ligands bearing bulky N-alkyl substituents, which enables a wide range of aryl ethers to be coupled with organoboron nucleophiles. Moreover, the use of N-alkyl-substituted NHC ligands allows the use of alkynylmagnesium reagents, thereby realizing the first Sonogashira-type reaction of anisoles. From a mechanistic perspective, nickel-catalyzed cross-couplings of aryl ethers are at a nascent stage, in particular regarding the mode of activation of C(aryl)-O bonds. Oxidative addition is one plausible pathway, although such a process has not been fully verified experimentally. Nickel-catalyzed reductive cleavage of aryl ethers in the absence of an external reducing agent provides strong support for this oxidative addition process. Several other mechanisms have also been proposed. For example, Martin demonstrated a new possibility of the involvement of a Ni(I) species, which could mediate the cleavage of the C(aryl)-O bond via a redox-neutral pathway. The tolerance of aryl ethers under commonly used synthetic conditions enables alkoxy groups to serve as a platform for late-stage elaboration of complex molecules without any tedious protecting group manipulations. Aryl ethers are therefore not mere economical alternatives to aryl halides but also enable nonclassical synthetic strategies.

Cu(I) complexes with diethoxyphosphoryl-1,10-phenanthrolines in catalysis of C–C and C–heteroatom bonds formation

Diethoxyphosphoryl substituted 1,10-phenanthroline copper(I) complexes were tested as catalysts in the Sonogashira-type reaction, α-arylation of phosphoryl-stabilized C–H acids, C–N, C–P bond forming reactions (substitution reactions) and in the reaction of phenylacetylene and bis(pinacolato)diboron (addition reaction). The complexes demonstrate fairly high catalytic activity and in some cases their efficiency is superior to that of the parent Cu(phen)(PPh3)Br (phen=phenanthroline).

1-Ethyl-2-phenyl-3-[2-(trimethylsilyl)ethynyl]-1H-indole

The title compound, C21H23NSi, was synthesized by Sonogashira-type reaction of 1-ethyl-3-iodo-2-phenyl-1H-indole with tri­methyl­silyl­acetyl­ene. The indole ring system is nearly planar [maximum atomic deviation = 0.0244 (15) Å] and is oriented at a dihedral angle of 51.48 (4)° with respect to the phenyl ring. The supramolecular aggregation is completed by weak C—H⋯π inter­actions of the methylene and phenyl groups with the benzene and pyrrole rings of the indole ring system. The methyl groups of the tri­methyl­silyl unit are equally disordered over two sets of sites.

Synthesis of [2]Rotaxanes by the Copper-Mediated Threading Reactions of Aryl Iodides with Alkynes

The catalytic activity of the macrocyclic phenanthroline-copper(I) complex is utilized for the Sonogashira-type reaction to synthesize [2]rotaxanes. Thus, [2]rotaxanes were prepared by reactions between terminal alkynes and aryl iodides in the presence of the macrocyclic copper complex. Bulky substituents were introduced to the substrates to stabilize the rotaxane. The bond-forming reaction proceeded selectively inside the macrocyclic complex so that the rotaxanes could be synthesized.

Photocatalytic Arylation of Alkenes, Alkynes and Enones with Diazonium Salts

Teaching old dogs new tricks: Visible light photoredox catalysis improves the classic Meerwein arylation protocol significantly and allows the light-controlled arylation of alkenes, alkynes and enones by diazonium salts.

Tuning Chemoselectivity in Iron-Catalyzed Sonogashira-Type Reactions Using a Bisphosphine Ligand with Peripheral Steric Bulk: Selective Alkynylation of Nonactivated Alkyl Halides

Tuning Chemoselectivity in Iron-Catalyzed Sonogashira-Type Reactions Using a Bisphosphine Ligand with Peripheral Steric Bulk: Selective Alkynylation of Nonactivated Alkyl Halides

Au(I)/Au(III)-catalyzed Sonogashira-type reactions of functionalized terminal alkynes with arylboronic acids under mild conditions

A straightforward, efficient, and reliable redox catalyst system for the Au(I)/Au(III)-catalyzed Sonogashira cross-coupling reaction of functionalized terminal alkynes with arylboronic acids under mild conditions has been developed.

Inexpensive Copper/Iron-Cocatalyzed Reactions

Compared with other transition metals, copper and iron saltsare inexpensive and stable to air and moisture. Moreover, iron isconsidered as an environmentally friendly catalyst. Due to these benigncharacteristics, both copper and iron catalysis have been extensively- investigated.More recently, inexpensive copper/iron-cocatalyzed reactionshave presented an attractive prospect for organic synthesis. Thisreview presents recent progress in copper/iron-cocatalyzedarylation, alkynylation, C-H functionalization, and conjugateaddition reactions. 1 Introduction 2 Arylation Reactions 2.1 C-N Bond Formation 2.2 C-O Bond Formation 2.3 C-S Bond Formation 2.4 Summary 3 Alkynylation Coupling Reactions 3.1 Sonogashira-Type Reactions 3.2 Glaser-Type Coupling 4 C-H Functionalization 5 Conjugate Addition Reactions 6 Conclusion

Bis(μ-iodo)bis((−)-sparteine)dicopper(I) catalyzed Sonogashira-type reaction under palladium and phosphine-free conditions

An efficient and inexpensive protocol for the Sonogashira-type cross coupling reactions of phenylacetylenes with a variety of haloarenes including activated aryl chlorides employing the structurally well-characterized bis(μ-iodo)bis((−)-sparteine)dicopper(I) catalyst is described.

Electrochemical generation of silver acetylides from terminal alkynes with a Ag anode and integration into sequential Pd-catalysed coupling with arylboronic acids

An electro-oxidative method for generating silver acetylides from acetylenes with a Ag anode was developed. The reaction could be integrated into a Pd-catalysed electrochemical Sonogashira-type reaction. In the presence of the catalytic amount of Pd(OAc)(2) and 4-BzO-TEMPO, electro-generated silver acetylides reacted immediately with arylboronic acids to afford the corresponding coupling adducts in high yields.

Hollow palladium–cobalt bimetallic nanospheres as an efficient and reusable catalyst for Sonogashira-type reactions

The synthesis and characterization of hollow Pd–Co bimetallic nanospheres are reported. During Sonogashira-type coupling reactions between aryl halides and terminal alkynes in aqueous medium, these hollow materials exhibited much higher activity than the solid counterpart nanoparticles. Moreover, the catalytic activity could be adjusted via changing the catalyst composition. The enhanced activity was attributed to both the hollow chamber structure and the promotional effect of Co-dopants, which provided more Pd active sites for the reactants.

ChemInform Abstract: Pd‐EnCat TPP30 as a Catalyst for the Generation of Highly Functionalized Aryl‐ and Alkenyl‐Substituted Acetylenes via Microwave‐Assisted Sonogashira Type Reactions.

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