Vincenzo Calò

Heck reaction in ionic liquids catalyzed by a Pd–benzothiazole carbene complex

Abstract A Pd-catalyst with benzothiazole carbene ligands allows, in ionic liquids as solvent, very fast and efficient reactions of haloaromatics with alkenes.

Heck reaction of β-substituted acrylates in ionic liquids catalyzed by a Pd-benzothiazole carbene complex

Abstract A Pd-catalyst with benzothiazole carbene as ligands allows, in tetrabutylammonium bromide melt as solvent, very fast and efficient reactions of haloaromatics with β-substituted acrylates.

Pd–benzothiazole carbene catalysed carbonylation of aryl halides in ionic liquids

Abstract The carbonylations of aryl halides with the Pd–carbene catalyst 1 were studied both in molecular solvents and in ionic liquids (ILs). Among the ILs, tetrabutylammonium bromide (TBAB) was found to give better results. Under these conditions the catalyst, when recovered and reused, did not show a significant decrease of activity. The role of TBAB on the catalyst stability is discussed.

Glucose as a Clean and Renewable Reductant in the Pd-Nanoparticle-Catalyzed Reductive Homocoupling of Bromo- and Chloroarenes in Water

An efficient and highly sustainable Ullmann-type homocoupling of bromo- and chloroarenes, including the more challenging electron-rich chloroarenes (e.g., 4-chloroanisole), catalyzed by in situ generated Pd colloids, is carried out in aqueous medium under relatively mild conditions (temperatures ranging from 40 to 90 degrees C). Glucose is used as a clean and renewable reductant, while tetrabutylammonium hydroxide (TBAOH) acts as base, surfactant, and phase-transfer agent, creating a favorable environment for the catalyst. Pd nanoparticle sizes, morphology, and chemical composition are ascertained by TEM and XPS analyses.

Arylation of α-substituted acrylates in ionic liquids catalyzed by a Pd–benzothiazole carbene complex

Abstract A Pd-catalyst with benzothiazole carbene as ligands allows, in tetrabutylammonium bromide melt as solvent, very fast and efficient reactions of bromoaromatics with 3-hydroxy-2-methylenealkanoates to give β-arylketones.

Palladium‐Nanoparticle‐Catalysed Ullmann Reactions in Ionic Liquids with Aldehydes as the Reductants: Scope and Mechanism

An efficient Ullmann-type reductive homocoupling of aryl, vinyl and heteroaryl halides can be promoted by an aldehyde in tetraalkylammonium ionic liquids under very mild reaction conditions. This simple procedure generates symmetrical biaryls under relatively mild conditions. The ionic liquid is crucial for this process because it behaves simultaneously as a base, ligand and reaction medium. The role of the aldehyde is also discussed and a general mechanism for this unusual reaction is proposed. These results open the way to a new efficient method of Pd-catalysed dehydrogenation of carbonyl compounds.

Synthesis and Crystal Structure of Bis(2,3‐dihydro‐3‐methylbenzothiazole‐2‐ylidene)palladium(II) Diiodide: The First Palladium Complex with Benzothiazole Carbene Ligands Suitable for Homogeneous Catalysis

The first diiodo palladium complex with nucleophilic benzothiazole carbenes as ligands has been synthesized and characterized. The complex, which is extraordinarily stable towards heat, oxygen, and moisture, has been found to show good catalytic activity in the Heck coupling reaction.

Palladium/Zirconium Oxide Nanocomposite as a Highly Recyclable Catalyst for C-C Coupling Reactions in Water

Palladium nanoparticles have been electrochemically supported on zirconium oxide nanostructured powders and all the nanomaterials have been characterized by several analytical techniques. The Pd/ZrO2 nanocatalyst is demonstrated to be a very efficient catalyst in Heck, Ullmann, and Suzuki reactions of aryl halides in water. The catalyst efficiency is attributed to the stabilization of Pd nanophases provided by tetra(alkyl)-ammonium hydroxide, which behaves both as base and PTC (phase transfer catalyst) agent.

Stereoselective synthesis of electrophilic spirocyclopropanes in ionic liquids

Abstract The reaction of β-oxosulfides of benzothiazole with Michael acceptors, in liquid tetrabutylammonium bromide and sodium bicarbonate as base, allows a stereoselective synthesis of spirocyclopropanes.

Contribution to the bromination of conjugate unsaturated ketones: Synthesis of α,β-unsaturated bromo ketones

Abstract Selective bromination of α,β-unsaturated ketones has been achieved by the action of 2,4,4,6-tetrabromocyclohexa-2,5-dienone. The stereochemistry, conformation and relative stability of the bromination products of some steroidic unsaturated ketones have been also determined.