Efficient Allylation of Nucleophiles Catalyzed by a Bifunctional Heterogeneous Palladium Complex-Tertiary Amine System

The copper-catalyzed selective monoalkylation of active methylene compounds with alkylsilyl peroxides

A novel method for a mild copper-catalyzed selective monoalkylation of active methylene compounds with various alkylsilyl peroxides has been developed. The reaction has a broad substrate scope and our mechanistic studies suggest the participation of radical species in this alkylation reaction.

Synthesis of 3-Carbonyl Trisubstituted Furans via Pd-Catalyzed Aerobic Cycloisomerization Reaction: Development and Mechanistic Studies

Herein, we report the synthesis of 3-carbonyl-trisubstituted furans via Pd-catalyzed oxidative cycloisomerization reactions of 2-alkenyl-1,3-dicarbonyl scaffolds, using molecular oxygen as the sole oxidant to regenerate active palladium catalytic species, featuring good functional tolerance and mild reaction conditions. Deep investigation of intermediates and transition states of the reaction mechanism were conducted via experimental and DFT studies, providing a detailed mechanistical profile. The new developed methodology presents a greener alternative to Wacker-type cycloisomerizations and avoids the use of stoichiometric amounts of oxidants and strong acid additives.

Heterogeneous Supported Palladium Catalysts for Liquid-Phase Allylation of Nucleophiles

In recent years, palladium-catalyzed allylation has become the focus of much research. However, conventional homogeneous Pd catalysts face problems regarding their recovery, reuse, and cost, especially with respect to green chemistry principles. Herein, we present an overview of the development of catalytic allylation with various heterogeneous Pd catalysts, because they can be easily and conveniently recovered and reused. We also emphasize the use of different solid supports such as polymers, silica, and other hybrid supports to inspire future research in this promising field. Moreover, the unique effects of support surfaces for enhancing catalysis by immobilized heterogeneous Pd species are introduced.

Direct Estimation of the Surface Location of Immobilized Functional Groups for Concerted Catalysis Using a Probe Molecule

The location of active sites during concerted catalysis by a metal complex and tertiary amine on a SiO2 surface is discussed based on the interaction between the functionalized SiO2 surface and a probe molecule, p-formyl phenylboronic acid. The interactions of the probe molecule with the surface functionalities, diamine ligand, and tertiary amine, were analyzed by FT-IR and solid-state (13)C and (11)B MAS NMR. For the catalyst exhibiting high 1,4-addition activity, the diamine ligand and tertiary amine base exist in closer proximity than in the catalyst with low activity.

Rational synthesis of Pd nanoparticle-embedded reduced graphene oxide frameworks with enhanced selective catalysis in water

A three-dimensional (3D) Pd-reduced graphene oxide framework (Pd-rGOF) with hierarchical macro- and mesoporous structures has been developed via covalence- and coordination-assisted self-assembly approach. In this facile fabrication process, GO was first cross-linked with triethylene tetramine (TETA) to form 3D GOF, in which well-dispersed and ultrasmall Pd nanoparticles (NPs) in situ grew and embedded the framework. The obtained nanopores, 3D Pd-rGOF, can act as nanoreactors to help the reaction substrates thoroughly contact with the surface of Pd NPs, thereby exhibiting high activity and selectivity toward the Tsuji-Trost reaction in water, with 99% conversion and selectivity for most substrates. Moreover, the 3D Pd-rGOF catalyst can be reused more than ten times without significant loss of activity, rendering this catalyst long-term stability. The abovementioned observations make the rGOF a universal platform to coordinate other noble metal ions (NM) to construct desired NM-rGOF nanocatalysts with improved activity, selectivity, and durability that can be used in a broad range of practical applications.

One “Click” to controlled bifunctional supported catalysts for the Cu/TEMPO-catalyzed aerobic oxidation of alcohols

A modular strategy is described for the preparation and molecular engineering of multifunctional surfaces using CuAAC chemistry and is applied to the model Cu/TEMPO-catalyzed aerobic oxidation of benzyl alcohol.

A Pd–bisphosphine complex and organic functionalities immobilized on the same SiO2 surface: detailed characterization and its use as an efficient catalyst for allylation

A Pd–bisphosphine complex and several organic functionalities were immobilized on the same SiO₂ surface.

Highly selective palladium-benzothiazole carbene-catalyzed allylation of active methylene compounds under neutral conditions

The Pd–benzothiazol-2-ylidene complex I was found to be a chemoselective catalyst for the Tsuji–Trost allylation of active methylene compounds carried out under neutral conditions and using carbonates as allylating agents. The proposed protocol consists in a simplified procedure adopting an in situ prepared catalyst from Pd₂dba₃ and 3-methylbenzothiazolium salt V as precursors. A comparison of the performance of benzothiazole carbene with phosphanes and an analogous imidazolium carbene ligand is also proposed.

Heterogeneous double-activation catalysis: Rh complex and tertiary amine on the same solid surface for the 1,4-addition reaction of aryl- and alkylboronic acids

Double-activation catalysis by a rhodium complex/tertiary amine catalyst for the 1,4-addition of organoboronic acids was investigated.