Practical Synthesis of Unsymmetrical Diarylacetylenes from Propiolic Acid and Two Different Aryl Bromides

Ionic Liquids in Metal, Photo-, Electro-, and (Bio) Catalysis

Ionic liquids (ILs) have unique physicochemical properties that make them advantageous for catalysis, such as low vapor pressure, non-flammability, high thermal and chemical stabilities, and the ability to enhance the activity and stability of (bio)catalysts. ILs can improve the efficiency, selectivity, and sustainability of bio(transformations) by acting as activators of enzymes, selectively dissolving substrates and products, and reducing toxicity. They can also be recycled and reused multiple times without losing their effectiveness. ILs based on imidazolium cation are preferred for structural organization aspects, with a semiorganized layer surrounding the catalyst. ILs act as a container, providing a confined space that allows modulation of electronic and geometric effects, miscibility of reactants and products, and residence time of species. ILs can stabilize ionic and radical species and control the catalytic activity of dynamic processes. Supported IL phase (SILP) derivatives and polymeric ILs (PILs) are good options for molecular engineering of greener catalytic processes. The major factors governing metal, photo-, electro-, and biocatalysts in ILs are discussed in detail based on the vast literature available over the past two and a half decades. Catalytic reactions, ranging from hydrogenation and cross-coupling to oxidations, promoted by homogeneous and heterogeneous catalysts in both single and multiphase conditions, are extensively reviewed and discussed considering the knowledge accumulated until now.

Synthesis of (Deoxy)difluoromethylated Phosphines by Reaction of R2P(O)H with TMSCF3 and Their Application in Cu(I) Clusters in Sonogashira Coupling

R₂PCF₂H ligands and their R₂P(O)CF₂H precursors were synthesized from R₂P(O)H with TMSCF₃ by simply modulating the H₂O concentration via deoxydifluoromethylation and difluoromethylation. The air sensitive R₂PCF₂H phosphines can be stabilized in Cu(I) clusters as ligands. Within these Cu(I) clusters, the Sonogashira cross-coupling reaction can proceed fast and efficiently using terminal alkynes and aryl iodides within 15 min at room temperature under air to give a variety of diaryl(alkyl)acetylenes in good yields (49 examples, yields of ≤99%). Six of the internal alkynes present in drug precursors can be obtained using this protocol in good yields. The mechanism is proposed on the basis of control experiments.

An Efficient and Sustainable Approach to Decarboxylative Cross-Coupling Using Silica Coated Magnetic Copper Nanocatalyst for the Synthesis of Internal Alkynes

A highly efficient magnetically separable copper nanocatalyst has been developed for decarboxylative cross-coupling reaction for the alkynylation of haloarenes using alkynoic acid as a reaction partner. The chemical nature, morphology, size, and magnetic properties of the prepared nanocatalyst were studied by SEM, TEM, EDS, FT-IR, VSM, and ICP techniques. Remarkably, this catalyst represents the first successful copper based heterogeneous system for this type of coupling that provides a low-cost, stable, and environmentally friendly magnetically recoverable entity that can be re-used for seven consecutive runs without appreciable loss in its catalytic performance.

Pd-Catalyzed decarboxylative alkynylation of alkynyl carboxylic acids with arylsulfonyl hydrazides via a desulfinative process

The decarboxylative alkynylation of alkynyl carboxylic acids and arylsulfonyl hydrazides by desulfinative coupling could provide aryl alkynes in satisfactory yields by either judiciously selecting palladium catalysts or modulating phosphine ligands under mild conditions.

Sonogashira coupling in 3D-printed NMR cuvettes: synthesis and properties of arylnaphthylalkynes

A set of push–pull substituted arylnaphthylalkynes has been synthesized under inert gas conditions in 3D-printed cuvettes out of NMR-transparent polyamide and their optical properties were investigated.

Controlling chemoselectivity in copper-catalyzed decarboxylative A3/A3 cross-couplings: direct formation of unsymmetrical 1,4-diamino-2-butynes

A direct cross-coupling of propiolic acid with two kinds of in situ formed iminiums has been achieved via a CuI/CuCl₂-catalyzed decarboxylative A³/A³ domino process.

Rapid access to unsymmetrical tolanes and alkynones by sequentially palladium-catalyzed one-pot processes

Alkynones and unsymmetrically substituted tolanes can be synthesized via consecutive three-component Kumada–(Negishi)–Sonogashira bisalkynylation sequences in good to excellent yields.

Supported palladium nanoparticles-catalyzed decarboxylative coupling approaches to aryl alkynes, indoles and pyrrolines synthesis

The polystyrene supported palladium (Pd@PS) nanoparticles catalyzed decarboxylative coupling of arylhalides and alkynyl carboxylic acids was developed for the synthesis of diaryl alkynes, indoles and pyrrolines.

Decarboxylative/Sonogashira-type cross-coupling using PdCl2(Cy*Phine)2

Expedient protocol to access a wide range of internal alkynes and symmetrical di(heteroaryl)alkynes via tandem decarboxylative–Sonogashira cross-coupling.

Palladium-catalyzed oxidative deacetonative coupling of 4-aryl-2-methyl-3-butyn-2-ols with H-phosphonates

A new and generally practical synthesis of alkynylphosphonates through a palladium-catalyzed consecutive Sonogashira/deacetonative process using aryl bromides, 2-methyl-3-butyn-2-ol and H-phosphonates is developed.

Practical synthesis of aryl-2-methyl-3-butyn-2-ols from aryl bromides via conventional and decarboxylative copper-free Sonogashira coupling reactions

Two efficient protocols for the palladium-catalyzed synthesis of aryl-2-methyl-3-butyn-2-ols from aryl bromides in the absence of copper were developed. A simple catalytic system consisting of Pd(OAc)₂ and P(p-tol)₃ using DBU as the base and THF as the solvent was found to be highly effective for the coupling reaction of 2-methyl-3-butyn-2-ol (4) with a wide range of aryl bromides in good to excellent yields. Analogously, the synthesis of aryl-2-methyl-3-butyn-2-ols was performed also through the decarboxylative coupling reaction of 4-hydroxy-4-methyl-2-pentynoic acid with aryl bromides, using a catalyst containing Pd(OAc)₂ in combination with SPhos or XPhos in the presence of tetra-n-butylammonium fluoride (TBAF) as the base and THF as the solvent. Therefore, new efficient approaches to the synthesis of terminal acetylenes from widely available aryl bromides rather than expensive iodides and using 4 or propiolic acid rather than TMS-acetylene as inexpensive alkyne sources are described.

Synthesis of diarylalkynes via tandem Sonogashira/decarboxylative reaction of aryl chlorides with propiolic acid

A tandem Sonogashira/decarboxylative coupling of aryl chlorides with propiolic acid for one-pot synthesis of diarylalkynes was developed.

One-pot synthesis of unsymmetrical diarylacetylenes via Sonogashira/deacetonation/Sonogashira cross-coupling of two different aryl chlorides with 2-methyl-3-butyn-2-ol

Synthesis of unsymmetrical diarylacetylenes via one-pot Sonogashira/Deacetonation/Sonogashira cross-coupling of two different aryl chlorides with 2-methyl-3-butyn-2-ol was developed.