Palladium Catalysed Reaction

Phosphino hydrazones represent a versatile class of nitrogen-containing phosphine ligands. Herein, we report a modular synthesis of phosphino hydrazone ligands by hydrazone condensation reaction of three different aryl hydrazines with 3-(diphenylphosphino)propanal (PCHO). Complexation reactions of these phosphino hydrazone ligands with palladium(II) and platinum(II) were investigated and the catalytic activity of the palladium(II) complexes was explored in a Cu-free Sonogashira cross-coupling reaction and achieving yields up to 96%...

A novel C3-symmetric tris-imidazolium tribromide salt 3, featuring 1,3,5-substituted triethynylbenzene, was used for the preparation of a trinuclear PdII PEPPSI (pyridine-enhanced precatalyst preparation stabilization and initiation) type complex by triple C2 deprotonation followed by the addition of PdCl2. Trinuclear PdII complex possessing a combination of NHC and PPh3 ligands has also been synthesized. The corresponding mononuclear palladium(II) complexes have also been synthesized for the comparison purpose...

Methods for the enantioselective direct oxygenation of internal alkenes have provided chemists with versatile and powerful toolboxes for the synthesis of optically pure alcohols, one of the most privileged structural motifs. Regioselectivity, however, remains a formidable challenge in the functionalization of internal alkenes. Here we report a palladium-catalysed highly regio- and enantioselective remote 1,n-dioxygenation (n ≥ 4) of internal alkenes with engineered pyridine-oxazoline (Pyox) ligands...

Hydrogenation of phenol to cyclohexanone/cyclohexanol is an important reaction in production of nylon-6, nylon-66 and in petroleum industry. Liquid phase phenol hydrogenation over Pd-CuO/CeO2 was carried out under mild conditions. Palladium impregnated over CuO/CeO2 synthesized by co-precipitation method showed excellent catalytic activity for phenol hydrogenation (99% conversion with 80% cyclohexanol yield) at 90ºC and 10bar H2 pressure in water. Commercial 10%Pd/C showed only 8% phenol conversion under identical conditions...

C-C bond formation based on palladium-catalysed cross-coupling reactions using organolithium reagents has seen major breakthroughs in the past decade. However, the use of inert conditions, as well as slow addition of the organolithium species, is generally required. Here we describe the Pd-catalysed cross-coupling of C36 H74 -gelated organolithium reagents with aryl bromides. The reaction proceeds in 5 min at room temperature, while eliminating the previously required slow addition, and strict use of inert atmosphere...

A palladium-catalysed aromative benzylic allylation and allenylation of benzyl chlorides with allyl and allenyl pinacolborates is described for the first time. The reactions proceed smoothly in the presence of a bidentate phosphine ligand to afford normal cross-coupling products in good yields. This novel synthetic procedure exhibits good tolerance for various electron-withdrawing and -donating functional groups linked to aromatic rings and is also well tolerant of sensitive functional groups such as NO2 , CF3 , CN, and COOMe...

This article examines a selection of case studies that highlight key strategies that have enabled the structural authentication of important species that shed light on fundamental on-cycle intermediates in palladium- and nickel-catalysed C-C, C-N, and C-O cross-coupling reactions. Particular emphasis is placed on studies in which the structures of rather intractable intermediates have been confirmed unambiguously by X-ray crystallography, while also contextualising the mechanistic insights that these reports have contributed...

Palladium-catalysed Suzuki-Miyaura couplings of α,β-unsaturated acid derivatives are challenging due to the susceptibility of their CC bonds adjacent to carbonyl groups. In this work, we describe a highly selective C-O activation approach to this transformation using superactive triazine esters and organoborons as coupling partners. 42 α,β-unsaturated ketones with diverse functional groups have been prepared with this method. The mechanistic investigation unveiled that the dual function of triazine for activating the C-O bond and stabilizing non-covalent interactions between the catalyst and substrate is critical for the reaction's success...

We report the synthesis of a new palladium complex (1a) bearing two different P-donors, di(1-adamantyl)phosphinous acid and triphenylphosphine. A heteroleptic complex with a phosphinous acid ligand has rarely been reported. With phenyl bromide and di- p -tolylphosphine oxide as reagents, PPh3 -stabilised 1a was proved to be a noteworthy Pd(II) precatalyst for carbon-phosphorus bond formation. 1a-catalysed Hirao coupling could be efficiently made in environmentally benign ethanol. Reacting for 10 to 120 minutes, aryl bromides equipped with electron-donating or electron-withdrawing groups were successfully catalysed...

We herein report α-arylsulfonyloxyacrylates as a kind of useful and attractive O -centered electrophiles for Suzuki cross-coupling reactions. A range of α-(hetero)aryl substituted acrylates has been prepared via the palladium-catalysed C-C cross-coupling reactions between potassium (hetero)aryltrifluoroborates and α-arylsulfonyloxyacrylates. Moreover, α-arylsulfonyloxyacrylate could also react with B-alkyl-9-BBN to produce α-alkyl substituted acrylates. The synthetic application of this new method was demonstrated by the preparation of the intermediate for synthesis of retinoid X receptors-selective retinoids...

In the synergistic dual catalytic process, the kinetics of the catalytic cycles must be balanced for the successful outcome of the reaction. Therefore, the analysis of the kinetics of the independent catalytic cycles is essential for such reactions, as it enables their relational optimization as well as their design. Here we describe an analysis of the mechanism of a catalytic synergistic bimetallic reaction through the experimental study of a palladium-catalysed cross-coupling of aryl halides with terminal alkynes, an example of a monometallic dual catalytic process...

A palladium-catalysed direct arene C-H fluoroalkoxylation of 4-aryl-pyrrolo[2,3- d ]pyrimidine derivatives with fluorinated alcohols is described. Highly site-selective mono- or bis-fluoroalkoxylation can be achieved by tuning the reaction conditions, affording various fluoroalkoxylated pyrrolo[2,3- d ]pyrimidine derivatives in moderate to good yields, which offer rational tailoring of their biological activity for their application in the field of pharmaceutical chemistry.

A new family of diterpene-type aminotriol derivatives has been synthesised from stevioside in a stereoselective manner. The key intermediate spiro-epoxide was prepared through the methyl ester of the allilyc diol derived from steviol. The oxirane ring was opened with primary and secondary amines, providing a versatile library of aminotriols. The corresponding primary aminotriol was formed by palladium-catalysed hydrogenation, and an N , O -heterocyclic compound was synthesised in a regioselective reaction. All new compounds were characterised by 1D- and 2D-NMR techniques and HRMS measurements...

A palladium-catalysed carbon-carbon bond-forming reaction via deaminative/decarboxylative cross-coupling of organoammonium salts with carboxylic acids was developed. Under the reaction conditions, polyfluoroaromatic carboxylic acids, propiolic acids and α-cyano benzyl carboxylic acid reacted smoothly with benzyl ammonium salts to produce the corresponding carbon-carbon coupling products in good-to-excellent yields.

The unique characteristic of superatoms to show chemical properties like those of individual atoms opens a new avenue towards replacing noble metals as catalysts. Given the similar electronic structures of the ZrO superatom and the Pd atom, the CO oxidation mechanisms catalysed by (ZrO) n (n = 1-4) clusters were investigated in detail to evaluate their catalytic performance. Our results reveal that a single ZrO superatom exhibits superior catalytic ability in CO oxidation than both larger (ZrO) n (n = 2-4) clusters and a Pd atom, indicating the promising potential of ZrO as a "single-superatom catalyst"...

Transition metal-catalysed C-H functionalization reactions are one of the most efficient synthetic methodologies to construct carbon-carbon and carbon-heteroatom bonds. The initial developments in the field were largely dominated by expensive transition metal catalysts. However, in the past decade, the focus of the catalyst shifted to first-row transition metals and copper catalysis contributed significantly. Abundant, cost-effective, and less toxic copper catalysts are an ideal green alternative to palladium and similar metals...

Pancreatic cancer is the most severe among other cancers due to its late detection and less chance of survivability. Heterocycles are proven ring systems in the treatment of various cancers and this is due to the presence of two biodynamic molecules combined, have a greater synergistic efficacy in many anticancer drugs. Quinoline and pyridine ring systems are brought together to obtain greater potency and this is achieved by coupling the both using Pd-catalyst, and in the present investigation, Suzuki-Miyaura coupling (SMC) reactions are adopted to generate potent molecular entities...

Although nucleophilic benzylation-type reaction to introduce various aromatic systems into molecules has been widely explored, the related pyrrolylmethylation version remains to be disclosed. Reported herein is a palladium-catalysed multiple auto-tandem reaction between N- Ts propargylamines, allyl carbonates and aldimines in the presence of an acid, proceeding through sequential allylic amination, cycloisomerisation, vinylogous addition and aromatisation steps. A diversity of formal pyrrolylmethylated amine products were finally furnished efficiently...

A palladium(II) hydride complex supported by a benzene-based PNCNP pincer ligand, [2,6-( t Bu2 PNH)2 C6 H3 ]PdH (1), has been synthesized via two different routes: the reaction of the corresponding chloride complex with LiAlH4 and the reaction of the corresponding nitrate complex with KOCH3 . Complex 1 exhibits strong deprotonating ability and versatile catalytic activity. Acetamide can be readily deprotonated by complex 1 to form the corresponding acetamido complex, [2,6-( t Bu2 PNH)2 C6 H3 ]PdNHC(O)CH3 , in high yield...

A general palladium-catalysed selective C-H halogenation reaction is reported, which was successfully achieved for a large variety of functionalized aromatic rings incorporating diverse N-directing groups. By using simple alkali halides of MX type as the nucleophilic reagent source (M = Li, Na, K, Cs and X = I, Br and Cl), and phenyliodanediacetate oxidant, clean C-H-iodination, bromination and chlorination reactions were performed. This general protocol of selective ortho -monohalogenation, which complements but contrasts with the classical methods using electrophilic reagents, is achievable in a short time (30 min) with microwave irradiation assistance...