Direct Synthesis of Biphenyl-2-carbonitriles by Rh(III)-Catalyzed C-H Hiyama Cross-Coupling in Water

This method represents an efficient rhodium(III)-catalyzed o-C-H arylation of readily available benzimidate derivatives with diverse arylsilanes in water as a sustainable solvent, enabling the straightforward synthesis of potentially useful biphenyl-2-carbonitrile derivatives. This silicon-based protocol employs benzimidates as both an efficacious directing group and the source of a nitrile group.

o-Acetoxylation of oxo-benzoxazines via C–H activation by palladium(ii)/aluminium oxide

Direct activation of sp2 C–H bonds by a palladium catalyst has received significant attention in organic chemistry.

Chitosan-starch biopolymer modified kaolin supported Pd nanoparticles for the oxidative esterification of aryl aldehydes

A mild and efficient green protocol has been disclosed for selective oxidative esterification of various aldehydes over a novel Pd fabricated chitosan-starch polyplex encapsulated Kaolin (Kaolin@CS-starch-Pd) as a heterogeneous and reusable biocompatible nanocatalyst. Molecular oxygen was used as an oxidizing agent to generate water as the sole by-product. A wide variety of aldehydes was converted to their methyl esters in high yields. The process involved gentle reaction conditions to avoid any type of pre-activation. Structural features of the catalyst were determined through FT-IR, FE-SEM, TEM, EDX, elemental mapping, XRD and ICP-OES analyses. The material was found to be stable enough toward Pd leaching. Durability of Kaolin@CS-starch-Pd was further justified by retaining its catalytic activity through successful reusability for several times.

Application of combined cyanide sources in cyanation reactions

The cyanation reaction is a key transformation due to the wide-ranging applications of nitrile compounds in organic chemistry. Traditionally, the cyanation reaction employs metal cyanides as cyanide sources, which are toxic and environmentally unfriendly. Very recently, many excellent examples of using combined cyanide sources as cyanating agents have been reported. This review summarizes the applications of combined cyano-group sources in a variety of cyanation reactions.

Green strategies for transition metal-catalyzed C–H activation in molecular syntheses

Sustainable strategies for the activation of inert C–H bonds towards improved resource-economy.

Directing group strategies in catalytic sp2 C–H cyanations: scope, mechanism and limitations

Directing group strategy in transition metal catalyzed sp² C–H bond cyanation has contributed to the direct conversion of hydrocarbons to cyano-containing compounds. Recent developments in transition metal-mediated sp² C–H bond cyanation using this strategy are reviewed.

Metallic palladium, PdO, and palladium supported on metal oxides for the Suzuki–Miyaura cross-coupling reaction: a unified view of the process of formation of the catalytically active species in solution

The nature of the true catalytic species in the Suzuki–Miyaura coupling starting from metallic palladium, PdO, and metal oxide-supported Pd is critically reviewed.

Palladium nanoparticles supported on organofunctionalized kaolin as an efficient heterogeneous catalyst for directed C–H functionalization of arylpyrazoles

A heterogeneous catalyst system based on the immobilization of Pd⁰ nanoparticles onto organofunctionalized kaolin is reported with a view to introducing new synthetic routes of directed C–H functionalization of arylpyrazoles.

Conversion of Arylboronic Acids to Tetrazoles Catalyzed by ONO Pincer-Type Palladium Complex

A convenient synthesis of a library of tetrazoles through a novel and operationally simple protocol effecting the direct conversion of arylboronic acids catalyzed by a new ONO pincer-type Pd(II) complex under mild reaction conditions using the readily available reagents is reported. The palladium complex was reused up to four cycles in an open-flask condition.

Catalytic C-H bond functionalisation chemistry: the case for quasi-heterogeneous catalysis

This feature article examines the potential of heterogeneous Pd species to mediate catalytic C-H bond functionalisation processes employing suitable substrates (e.g. aromatic/heteroaromatic compounds). A focus is placed on the reactivity of supported and non-supported Pd nanoparticle (PdNPs) catalysts, in addition to the re-appropriation of well-established heterogeneous Pd catalysts such as Pd/C. Where possible, reasonable comparisons are made between PdNPs and traditional 'homogeneous' Pd precatalyst sources (which form PdNPs). The involvement of higher order Pd species in traditional cross-coupling processes, such as Mizoroki-Heck, Sonogashira and Suzuki-Miyaura reactions, allows the exemplification of potential future topics for study in the area of catalytic C-H bond functionalisation processes.

C–H bond cyanation of arenes using N,N-dimethylformamide and NH4HCO3 as a CN source over a hydroxyapatite supported copper catalyst

Copper dispersed on Ca₅(PO₄)₃OH has been identified as an excellent heterogeneous catalyst for the in situ generation of ‘CN’ from NH₄HCO₃ and N,N-dimethylformamide, in the C–H bond activation of 2-phenylpyridine.