A Convenient Procedure for Sonogashira Reactions Using Propyne

A modified Sonogashira coupling of aryl iodides and propyne was achieved using only two equivalents of propyne in THF from -78°C to room temperature.

Nickel-catalyzed deaminative Sonogashira coupling of alkylpyridinium salts enabled by NN2 pincer ligand

Alkynes are amongst the most valuable functional groups in organic chemistry and widely used in chemical biology, pharmacy, and materials science. However, the preparation of alkyl-substituted alkynes still remains elusive. Here, we show a nickel-catalyzed deaminative Sonogashira coupling of alkylpyridinium salts. Key to the success of this coupling is the development of an easily accessible and bench-stable amide-type pincer ligand. This ligand allows naturally abundant alkyl amines as alkylating agents in Sonogashira reactions, and produces diverse alkynes in excellent yields under mild conditions. Salient merits of this chemistry include broad substrate scope and functional group tolerance, gram-scale synthesis, one-pot transformation, versatile late-stage derivatizations as well as the use of inexpensive pre-catalyst and readily available substrates. The high efficiency and strong practicability bode well for the widespread applications of this strategy in constructing functional molecules, materials, and fine chemicals.

Palladium Nanoparticles Supported on Smopex-234® as Valuable Catalysts for the Synthesis of Heterocycles

Supported catalysts are important tools for developing green-economy-based processes. Palladium nanoparticles (NPs) that are immobilized on two fibers developed as metal scavengers (i.e., Smopex®-234 and Smopex®-111, 1% w/w) have been prepared and tested in copper-free cyclocarbonylative Sonogashira reactions. Their catalytic activity has been compared with that of a homogeneous catalyst (i.e., PdCl2(PPh3)2). Pd/Smopex®-234 showed high activity and selectivity in the synthesis of functionalized heterocycles, such as phthalans and isochromans, even when working with a very low amount of palladium (0.2–0.5 mol%). The extension of Pd/Smopex®-234 promoted cyclocarbonylative reactions to propargyl and homopropargyl amides afforded the corresponding isoindoline and dihydrobenzazepine derivatives. A preliminary test on Pd NPs leaching into the solution (1.7 × 10−3 mg) seems to indicate that, at the end of the reaction, almost all of the active metal is present on the fiber surface.

Nickel-Catalyzed Deaminative Sonogashira Coupling of Alkylpyridinium Salts Enabled by a New NN2 Pincer Ligand

Alkynes are amongst the most valuable functional groups in organic chemistry and widely used in chemical biology, pharmacy, and materials science. However, the preparation of alkyl-substituted alkynes still remains elusive. Herein, a novel transformation is disclosed that enables the coupling of terminal alkynes with alkylpyridinium salts under Ni-catalysis. Key to the success of this coupling was the development of a new and readily accessible amide-type pincer ligand. This ligand allows naturally abundant alkyl amines as alkylating agents in Sonogashira reactions for the first time, and leads to diverse alkynes in excellent yields under mild conditions. Salient merits of this chemistry include broad substrates scope and functional group tolerance, gram-scale synthesis, one-pot transformation, versatile late-stage derivatizations as well as the use of inexpensive pre-catalyst and readily available substrates. The high efficiency and strong practicability bode well for the widespread applications of this strategy in constructing functional molecules, materials, and fine chemicals.

Application of Bimetallic and Trimetallic Nanoparticles Supported on Graphene as novel Heterogeneous Catalysts in the Reduction of Nitroarenes, Homo-coupling, Suzuki-Miyaura and Sonogashira Reactions

In the last decade, the use of heterogeneous catalysts based on Metal Nanoparticles (MNPs) has attracted increasing attention due to their prominence as nanocatalysts in several key chemical transformations. Notably, it is well identified that supporting Metal Nanoparticles (MNPs) with suitable solid surfaces can protect the MNPs from leaching, deactivation, and also increasing its ease of separation and possible reusability. Graphene oxide (GO) as a conductive surface could have non-covalent bonding interactions like hydrogen bonding, electrostatic and π –π* stacking interactions with substrate leading to activation of the substrate. Remarkably, it is recognized that bimetallic nanoparticles supported on graphene oxide often show novel properties that are not present on either of the parent metal or surfaces. In this review, we tried to reveal the potential advantages of bimetallic and trimetallic nanoparticles supported on graphene oxide in organic transformations, including the reduction of nitroarenes, Suzuki-Miyaura and Sonogashira coupling reactions.