Alkoxy- and amidocarbonylation of functionalised aryl and heteroaryl halides catalysed by a Bedford palladacycle and dppf: a comparison with the primary Pd(ii) precursors (PhCN)2PdCl2 and Pd(OAc)2

Aminophosphine Palladium Pincer-Catalyzed Carbonylative Sonogashira and Suzuki-Miyaura Cross-Coupling with High Catalytic Turnovers

This work documents the first palladium pincer complex-catalyzed carbonylative Sonogashira (CS) and carbonylative Suzuki-Miyaura (CSM) cross-coupling. Compared to previous protocols, which employ hazardous and toxic solvents, the aminophosphine pincer complex {[C₆H₃-2,6-(NHP{piperidinyl}₂)₂]Pd(Cl)} (III) catalyzes both the cross-coupling reactions in propylene carbonate, an eco-friendly and sustainable polar aprotic solvent. Advantageously, employing III allows the CS cross-coupling to be carried out at a palladium loading of 10^-4 mol % and the CSM cross-coupling to be carried out at 10^-6 mol %, thus resulting in catalytic turnovers of 10⁵ and 10⁷, respectively. Relative comparison of the pincer complex with conventional palladium precursors Pd(OAc)₂ and PdCl₂(PPh₃)₂ shows the efficiency and robustness of the pincer complex in effecting higher catalytic activity at low palladium loadings.

Palladacycle-Catalyzed Carbonylative Suzuki-Miyaura Coupling with High Turnover Number and Turnover Frequency

This work reports the carbonylative Suzuki-Miyaura coupling of aryl iodides catalyzed by palladacycles. More importantly, the palladacycles have been used to generate high turnover numbers (TON's) and turnover frequencies (TOF's). A range of aryl iodides can be coupled with arylboronic acids, generating TON's in the range of 10(6) to 10(7) and TOF's in the range of 10(5) to 10(6) h(-1). Comparison of the palladacycles with a conventional palladium source shows their superiority in generating high TON's and TOF's.

[Pd(C∧N)(X)(PPh3)] palladacycles react with 2,4,6-trifluorophenyl boronic acid to give stable transmetallation products of the type [Pd(C∧N)(2,4,6-F3C6H2)(PPh3)]

Evidence for a direct transmetallation between a palladacycle (containing acetate and imidate pseudohalides) with 2,4,6-trifluorophenyl boronic acid is presented in this paper.

Highly efficient aminocarbonylation of iodoarenes at atmospheric pressure catalyzed by a robust acenaphthoimidazolyidene allylic palladium complex

A robust allylic palladium-NHC complex was developed and exhibited extremely high catalytic activity toward aminocarbonylation of various (hetero)aryl iodides under atmospheric carbon monoxide pressure, in which a broad range of secondary and primary amines were well tolerated. In addition, the concise synthesis of an anticancer drug tamibarotene was accomplished even in a gram scale, further highlighting the practical applicability of the protocol.

Effective Pd-nanoparticle (PdNP)-catalyzed Negishi coupling involving alkylzinc reagents at room temperature

Pd(OAc)(2) is an efficient catalyst precursor for Negishi coupling in the presence of Bu(4)NBr. Secondary and primary alkylzinc reagents with beta-H and arylzinc reagents all reacted with aryl iodides at temperatures as low as -20 degrees C, giving moderate to good yields. One example of coupling between alkynylzinc reagents and aryl iodides was tested and the yield was good. Preliminary kinetic studies indicated that the process involved PdNPs as the active catalytic species.

Regioselective (site-selective) functionalisation of unsaturated halogenated nitrogen, oxygen and sulfur heterocycles by Pd-catalysed cross-couplings and direct arylation processes

This tutorial review focuses on several practical synthetic transformations utilising palladium catalysis that facilitate the synthesis of functionalized unsaturated heterocycles in a regioselective (site-selective) manner. Cross-couplings of electron-deficient, electron-neutral and electron-rich unsaturated halogenated heterocycles with various organometallic reagents, and other types of nucleophiles, are detailed. Direct arylation of electron-rich unsaturated heterocyclic compounds by C-H functionalization is also presented.