1,1-Regioselective alkenylboration of styrenes enabled by palladium catalysis

Despite the 1,2-difunctionalization reactions of styrenes have been well developed, the 1,1-regioselective addition reaction remains challenging. We disclose herein a palladium-catalyzed, highly 1,1-regioselective alkenylboration of styrenes by using alkenyl triflates and a diboron reagent as the coupling partners. A wide scope of styrenes derivatives and alkenyl triflates participate this reaction to provide the corresponding allyl boronates with high regioisomeric ratios. The success of this reaction is ascribed to the application of 1,10-phenanthroline-derivated ligand and the addition of ammonium chloride salt. Moreover, acrylate esters can also selectively afford the 1,1-alkenylboration products under the same reaction conditions.

Controlling Reactivity of Palladium Amides for Selective Carbonylation towards Urea and Oxamide Derivatives

Carbonylation reactions,crucial for carbonyl group incorporation,struggle with the inherent complexity of achieving selective mono-or double-carbonylation on single substrates,often due to competing reaction pathways.Herein,our study introduces a strategy employing palladium amides,harnessing their unique reactivity control,to direct the selective carbonylation of amines for the targeted synthesis of urea and oxamide derivatives.The palladium amide structure was elucidated using single-crystal X-ray diffraction.Controlled experiments and cyclic voltammetry studies further elucidate that the oxidation of palladium amide or its insertion into a carbonyl group diverges into distinct pathways.By employing sodium percarbonate as an eco-friendly oxidant and base,we have successfully constructed a switchable carbonylation system co-catalyzed by palladium and iodide under room temperature.The utilizing strategy in this study not only facilitates effective control over reaction selectivity but also mitigates the risk of explosions,a critical safety concern in traditional carbonylation methods.

Stereoselective fluoroarylation of 1,1-difluoroallenes enabled by palladium catalysis

A novel protocol for palladium-catalyzed fluoroarylation of 1,1-difluoroallenes was described here.The reaction proceeded smoothly under mild condition and various trifluoromethylated alkenes were obtained in moderate yields with excellent E selectivity.The mechanism involving a vital trifluoromethylated vinyl silver intermediate,which generated through the F-nucleophilic addition to 1,1-difluoroallenes,has been proposed.

Extrapolation of the gold-catalyzed cycloisomerization to the palladium-catalyzed cross-coupling/cycloisomerization of acetylenic alcohols for the synthesis of polysubstituted furans:Scope and application to tandem processes

This paper describes the development of an integrated approach for the preparation of diverse furan derivatives from acetylenic alcohols by gold and palladium catalyzed π-activation chemistry.Notably,this new method was found to be amenable to cyclooctyl-containing substrates,which represents a significant extension to this methodology compared with our previous reports.Furthermore,this newly developed method allowed for the direct construction of cyclooctyl furans from their synthetic precursors under Sonogashira conditions.Experimental results revealed that palladium played two major functions in these reactions,including（1） an essential catalyst in the cross-coupling reaction of the substrates;and（2）facilitating the cyclization of the acetylenic alcohol intermediates through a typical π-activation process.The scope of this chemistry was highlighted by the one-pot synthesis of 3-iodofuran,which provided an opportunity for further functionalization（via coupling methods）.Finally,the AuBr3 protocol was also elaborated to domino cyclization/C-H activation reactions,as well as the cyclization of acyclic precursors.Taken together,the results of this study demonstrate that gold and palladium catalysts can be used to complement each other in cyclization reactions.

Synergistic catalysis for stereocontrol of prochiral nucleophiles in palladium-catalyzed asymmetric allylic substitution

In contrast to the stereocontrol of the stereocenter at the allyl unit,the asymmetric induction of prochiral nucleophiles remains a challenge in Pd-catalyzed asymmetric allylic substitutions due to the remote distance between the chiral catalyst and the stereocenter established at prochiral nucleophile.Much effort has been devoted to solving this challenge through the elaborate design of chiral ligands.Recently,synergistic catalysis has gained increasing attention owing to its potential advantages over the traditional single palladium catalysis,such as improvement of reactivity and selectivity.This strategy,including bimetallic catalysis and Pd/organocatalysis,not only broadens the scope of prochiral nucleophiles,but also provides a simple and unified method for the stereocontrol of prochiral nucleophiles.This review summarizes the brief history and advances in this field.

Palladium-Catalyzed anti-Markovnikov Halosulfonamidation of Unactivated Alkene

Palladium-catalyzed regioselective amination of unactivated alkene remains a challenge and is of great interest.Herein,a three-component coupling of unactivated alkene,sulfonamide,and N-halo compounds accessing vicinal haloamine has been conceived.This aminohalogenation represents a modular and regioselective strategy.The electrophilic halogenating agent enables regioselective anti-Markovnikov aminopalladation and facilitates subsequent halogenation events.And this protocol is characterized by gram-scale syntheses and late-stage functionalizations.Of note,the recovered byproduct phthalimide allows for reusing by conversion to the starting material.

Palladium(Ⅱ)-Catalyzed Markovnikov Hydroalkynylation of Unactivated Terminal Alkenes

Alkynes are versatile synthons in organic synthesis,as well as important structural moieties in bioactive molecules.Recently,transition metal-catalyzed hydroalkynylation of alkenes has been developed with reactive alkenes and alkenes bearing directing groups.However,the regioselective hydroalkynylation of simple alkenes is still challenging.Herein,we have developed a palladium-catalyzed Markovnikov hydroalkynylation of unactivated terminal alkenes,which provides an efficient approach for the synthesis of branched alkynyl compounds under mild conditions.This reaction features excellent functional group tolerance,good reaction yields and excellent regioselectivity.Moreover,the asymmetric hydroalkynylation reaction has also been achieved with moderate enantioselectivity by introducing a sterically bulky chiral Pyox ligand.

Palladium-Catalyzed Skeletal Reorganization of Cyclobutanones Invoving Successive C—C Bond/C—H Bond Cleavage

The utilization of cyclobutanones as the synthon in transition metal catalysis has been made great success.Because C(carbonyl)−C bond of cyclobutanones can be cleaved through strain release.Despite those advancements,the main catalysts in literature are Rh catalysts or Ni catalysts and the reaction with C—H bond is still underdeveloped.Herein,we realized the first palladium-catalyzed skeletal reorganization of cyclobutanones involving successive cleavage of C(carbonyl)−C bonds and C—H bond cleavage,which constitutes an rapid access to diverse indanones.In contrast to the previous Rh-catalytic system,the Pd-catalytic system herein involves different mechanism and features several advantages:1)no need of directing group to facilitate the C(carbonyl)−C bond cleavage;2)much milder reaction condition and 3)simplified work-up.

Synthesis,Crystal Structure and Analysis of 6-Methoxycarbonylmethyl-7-methyl-6H-dibenzopyran

The compound 6-methoxycarbonylmethyl-7-methyl-6H-dibenzopyran has been synthesized by one-pot tandem reaction catalyzed by palladium and norbornene, which was initially structurally characterized by X-ray diffraction. The DSC spectra and chiral HPLC chromatography are reported. Crystal data of the title compound： C17H1603, orthorhombic system, space group Pbca, a = 14.507（3）, b = 9.3993（16）, c = 19.562（3） A, V= 2667.4（8） A3, Mr = 268.30, Dc = 1.336 g/cm3,μ = 0.091 mm-1, Z= 8, F （000） = 1136, R = 0.0653 and wR = 0.1447.

Palladium-catalyzed carbonylative cyclization of alkene-tethered indoles with phenols or arylboronic acids:Construction of carbonyl-containing indolo[2,1-a]isoquinoline derivatives

A novel palladium-catalyzed carbonylative cyclization of alkene-tethered indoles with phenols or arylboronic acids is described,which provides a facile approach to access indolo[2,1-a]isoquinoline scaffolds.This method employs benzene-1,3,5-triyl triformate(TFBen)as the CO surrogate for the incorporation of a carbonyl group into indolo[2,1-a]isoquinoline scaffolds,and a variety of carbonyl-containing indolo[2,1-a]isoquinoline derivatives are prepared in good yields.

Palladium-Catalyzed One-Step Synthesis of Stereodefined Difunctionalized Glycals

Efficiently modifying glycals by directly introducing functional groups into their double bonds is a longstanding challenge.Here,the strategy of introducing two different functional groups into 1-iodoglycals to obtain modified glycals in one step through palladium catalysis was reported for the first time,and the modified glycals contained stereodefined tetrasubstituted olefins.Using this method,various difunctionalized glycals that were difficult to form by other routes were synthesized in moderate to good yields.Control experiments and density functional theory calculations show that the palladium catalyst played dual roles in this transformation,namely,inducing nucleophilic substitution and catalyzing Suzuki coupling.The reaction intermediate was isolated and confirmed by X-ray crystallographic analysis.Furthermore,the gram-scale synthesis and facile deprotection of the target compound enhances the practicality of this strategy.

High-efficiency PdNi single-atom alloy catalyst toward cross-coupling reaction

The preparation of Pd-based catalysts with rich electrons and a high atom dispersion rate is of great significance for improving the reactivity of cross-coupling reactions,which is a powerful tool for pharmaceutical and fine chemical synthesis.Here,we report a PdNi single-atom alloy(SAA)catalyst in which isolated Pd single atoms are anchored onto the surface of Ni nanoparticles(NPs)applied for Suzuki coupling reactions and Heck coupling reactions.The 0.1%PdNi SAA exhibits extraordinary catalytic activity(reaction rate:17,032.25 mmol h^(-1)gPd^(-1))toward the Suzuki cross-coupling reaction between 4-bromoanisole and phenylboronic acid at 80℃for 1 h.The excellent activity is supposed to attribute to the 100 percent utilization rate of Pd atoms and the highly stable surface zero-valance Pd atoms,which provides abundant sites and electrons for the adsorption and fracture of the C-X(X=Cl,Br,I)bond.Moreover,our work demonstrates the excellent application prospect of SAAs for cross-coupling reactions.

Well-defined coordination environment breaks the bottleneck of organic synthesis:Single-atom palladium catalyzed hydrosilylation of internal alkynes

Single-atom site(SAS)catalysts have attracted considerable attention due to their excellent performance.However,most of the current research models of SAS catalysts are based on inorganic catalysts,where“metal and coordination atom interaction”cannot simulate the fine-tuning effect of organic ligands on metal catalytic centers in homogeneous catalysts.Therefore,certain chemical transformations in homogeneous catalysis cannot be perfectly replicated.Here,we used porous organic ligand polymers as the carrier,which effectively changes the charge regulation of nanoparticles and monoatomic metal catalysts.Drawing lessons from traditional homogeneous metal/ligand catalysis,we introduced various functional groups into the ligand polymers to adjust the electronic properties,and successfully realized the hydrosilylation of internal alkynes with high catalytic performance.The selectivity and catalytic efficiency under the Pd@POL-1 catalyst system were improved compared with previous studies.The internal alkynes with various structures can complete this reaction,and the ratio of E/Zcan reach up to 100:1.

Palladium-Catalyzed N-Alkylation of Amides and Amines with Alcohols Employing the Aerobic Relay Race Methodology

Possibly because homogeneous palladium catalysts are not typical borrowing hydrogen catalysts and ligands are thus ineffective in catalyst activation under conventional anaerobic conditions, they had not been used in the N-alkylation reactions of amines/amides with alcohols in the past. By employing the aerobic relay race methodol- ogy with Pd-catalyzed aerobic alcohol oxidation being a more effective protocol for alcohol activation, ligand-free homogeneous palladiums are successfully used as active catalysts in the dehydrative N-alkylation reactions, giving high yields and selectivities of the alkylated amides and amines. Mechanistic studies implied that the reaction most probably proceeds via the novel relay race mechanism we recently discovered and proposed.

Synthesis of π-extended dibenzo[d,k]ullazines by a palladium-catalyzed double annulation using arynes

An efficient Pd-catalyzed double annulation reaction of 1-(2,6-dibro mophenyl)-1 H-pyrroles with arynes is developed to synthesizeπ-extended dibenzo[d,k]ullazines in good to excellent yields.For the first time,the parent dibenzo[d,k]ullazine core is obtained and characterized.

New progress in theoretical studies on palladium-catalyzed C-C bond-forming reaction mechanisms

This review reports a series of mechanistic studies on Pd-catalyzed C-C cross-coupling reactions via density functional theory(DFT) calculations.A brief introduction of fundamental steps involved in these reactions is given,including oxidative addition,transmetallation and reductive elimination.We aim to provide an important review of recent progress on theoretical studies of palladium-catalyzed carbon-carbon cross-coupling reactions,including the C-C bond formation via C-H bond activation,decarboxylation,Pd(Ⅱ)/Pd(Ⅳ) catalytic cycle and double palladiums catalysis.

Palladium-catalyzed cyclization of 1-alkynyl-8-iodonaphthalene and double isocyanides for the synthesis of acenaphtho[1,2-b]pyrroles

A palladium-catalyzed formal[2+2+1]cyclization of 1-alkynyl-8-iodonaphthalene with double isocyanides is developed herein.The transformation worked well to produce a series of 7 H-acenaphtho[1,2-b]pyrrole with a broad reaction scope.Isocyanides play a dual role in the reaction.One is a C1 building block,and another is used as C1 N1 component.In the process,the[2+2+1]cyclization involves imidoylation,regioselective addition of imidoylpalladium species into alkyne,double imidoylation,and another addition of the resulting imidoylpalladium species into imine bonds.

Enantioselective and a-Regioselective Allylic Amination of Morita-Baylis-Hillman Acetates with Simple Aromatic Amines Catalyzed by Planarly Chiral Ligand/Palladium Catalyst

An asymmetric allylic amination of Morita-Baylis-Hillman acetates with simple aromatic amines catalyzed by planarly chiral ligand/palladium-catalyst was developed in good yield with excellent a-regioselectivity （a/γ up to 30 ： 1） and moderate enantioselectivity （up to 70% ee）.

A gram-scale synthesis of multi-substituted arenes via palladium catalyzed C–H halogenation

（6-Amino-2-chloro-3-fluorophenyl）methanol is prepared through both traditional methods and palladium catalyzed iterative C–H halogenation reactions.In comparison to traditional approach,the C–H functionalization strategy demonstrated a few advantages including milder reaction conditions higher yields,better selectivity and practicality,and high chemical diversity.

Synthesis of α-tertiary allylsilanes by palladium-catalyzed hydrosilylation of 1,1-disubstituted allenes

We herein report an effective hydrosilylation of 1,1-disubstituted allenes with a palladium catalyst modified by a monophosphorus ligand,leading to a series ofα-tertiary allylsilanes in high yields and exceptional regiose-lectivities.The employment of BI-DIME is essential for the high reactivities and selectivities.A chiralα-tertiary allylsilane is formed in excellent ee for the first time by employing a chiral monophosphorus ligand.