Ionic palladium complex as an efficient and recyclable catalyst for the carbonylative Sonogashira reaction

The neutral palladium（Ⅱ） complex bis-[1-（5＇-diphenylphosphinothiazol-2＇-yl）-imidazolyl]dichloropalladium（Ⅱ）（1A） ligated by thiazolylimidazolyl-based phosphine（L1） in which thiazolylimidazolyl acted as an S- and N-donor provider with weak coordinating nature,and the ionic complex bis-[1-（5＇-diphenylphosphinothiazol-2＇-yl）-3-methylimidazolium]dichloropalladium（Ⅱ） trifluoromethanesulfonate（2A） ligated by thiazolylimidazolium-based phosphine（L2） after quaternization of L1 using methyl trifluoromethanesulphonate were synthesized.It was found that the introduced positive charges and strong electron-withdrawing effect in 2A not only led to changes in the configuration and structural stability of the complex,but also lowered its catalytic performance in carbonylative Sonogashira reactions.These effects reveal the important role of the N-donor in 1A.In addition,as an ionic palladium complex,2A combined with the room-temperature ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate could be recycled eight times as the catalyst in carbonylative Sonogashira reactions without detectable metal leaching.

Carbonylative Coupling of 4,4’-Diiodobiphenyl Catalyzed by Pd(NHC) Complex

To develop a luminescent material with high color purity, luminous efficiency, and stability, we synthesized diketone by carbonylative Suzuki coupling in the presence of Pd(NHC) complex as the catalyst. Carbonylative coupling of 4,4’-diiodobiphenyl and phenylboronic acid was investigated to study in detail the catalytic ability of the Pd(NHC) complex. Reactions were carried out using both CO and metal carbonyls. Bis-(1,3-dihydro-1,3-dimethyl-2H-imidazol- 2-ylidene) diiodo palladium was used as the catalytic complex. Reaction products biphenyl-4,4’-diylbis (phenyl- methanone) 3 and (4’-iodobiphenyl-4-yl)(phenyl) methanone 4 were obtained as a result of CO insertion into the palladium(II)-aryl bond. However, when pyridine-4-yl boronic acid was used in place of phenylboronic acid as the starting reagent, synthetic reaction yielding 3 and 4 were found not to occur.

Recent Advances in Nickel Catalyzed Carbonylative Reactions via the Insertion of Carbon Monoxide

Carbonyl compounds have attracted considerable attention due to their extensive applications in drug discovery.Furthermore,they are important synthetic intermediates for the construction of carbon-carbon and carbon-heteroatom bonds.Transition-metal-catalyzed carbonylation via the insertion of co is one of the most efficient and straightforward strategies to access carbonyl compounds.However,most of the transition-metal-catalyzed carbonylative reactions require expensive and toxic noble-metal catalysts.Therefore,there is a growing demand for the exploration of nickel-catalyzed carbonylative reactions via the insertion of CO due to the earth abundance and low cost of nickel.Compared with the well-established palladium-catalyzed carbonylative reactions,nickel-catalyzed analogous transformations have been relatively underdeveloped.This is primarily because CO strongly binds to nickel,often resulting in catalyst poisoning.In recent years,some research groups have focused on using CO surrogates or NN_(2) pincer nickel catalyst to circumvent the formation of Ni(CO)_(4).Nickel-catalyzed carbonylation has been applied in the construction of carbonyl-containing compounds,such as ketones,carboxylic acids,thioesters,acyl chloride and carboxamides.

Chloride-Bridged Dimeric SalphenZr(IV) Cobaltate Catalyst Unleashes the Potential of Base-Free Carbonylative Polymerization for Biodegradable PHAs

Poly(3-hydroxyalkanoates) (PHAs) are a promising class of biodegradable polymers,exhibiting properties comparable to traditional petroleum-based counterparts.Nonetheless,the widespread commercialization of PHAs is hindered by the absence of an efficient and economically viable catalytic system,impeding their competitiveness against non-biodegradable polymers.In an effort to address this challenge,we present a study on a newly developed chloro-bridged dimeric salphen zirconium cobaltate complex for the direct synthesis of PHAs via carbonylative polymerization of epoxides.The catalytic system demonstrates favorable activity under mild reaction conditions,enabling complete monomer conversion and an impressive 92% selectivity towards PHA formation.Through meticulous control experiments and mechanistic studies,we have gained crucial insights into the polymerization process.Remarkably,our findings challenge the prevailing notion of sequential ring-opening polymerization of in-situ generated β-lactones as the primary pathway.Instead,we demonstrate that the polymerization predominantly proceeds through direct co-polymerization of epoxide and carbon monoxide,unveiling a unique and efficient mechanism for PHA synthesis.

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.

Total Synthesis of UCS1025A via Tandem Carbonylative Stille Cross Coupling and Diels-Alder Reactiont

We report an efficient and convergent strategy for the total synthesis of UCS1025A and its diastereomer tetra-epi-UCS1025A.Ucs1025A is a representative member of the naturally occurring pyrrolizidinone polyketides,from which members with potent antibacterial,antifungal,and anticancer activities have been identified.Our approach features a tandem carbonylative Stille cross coupling and Diels-Alder reaction to forge a key C-C bond and build the trans-decalin system.This tandem process utilizes carbon monoxide as a one-carbon linchpin to stitch a vinyl triflate and a vinylstannane together and form the desired enone moiety for the subsequent intramolecular Diels-Alder cyclization.Our synthesis also provides a versatile approach for the synthesis of other related pyrrolizidinone-containing polyketides.

Convenient Synthesis of Thioester-Substituted Oxindoles by Palladium-Catalyzed Thiocarbonylative Cyclization with Sulfonyl Chlorides as the Sulfur Source

A general and straightforward strategy for the synthesis of thioester-substituted oxindoles via a palladium-catalyzed thiocarbonyla-tive cyclization process has been developed.With sulfonyl chlorides as promising sulfur source,a wide range of thioester-substituted oxindoles were obtained in moderate to high yields.Both aryl and alkyl sulfonyl chlorides were well tolerated,and Mo(CO)6 played a dual role as both a CO source and a reductant in this approach.

Palladium Iodide-Catalyzed Selective Carbonylative Double Cyclization of 4-(2-Aminophenyl)-3-yn-1-ols to Dihydrofuroquinolinone Derivatives

The PdI_(2)/KI-catalyzed oxidative carbonylation of 4-(2-aminophenyl)-3-yn-1-ols,bearing two potential nucleophilic groups in suitable position selectively leads to dihydrofuroquinolinone derivatives in fair to high yields(60%—89%)and excellent turnover numbers(180—267 mol of product per mol of Pd)over 19 examples,through a mechanistic pathway involving initial O-cyclization followed by N-cyclocarbonylation.In such process,the selective catalytic construction of two rings and three new bonds is achieved in one synthetic step to afford high value added fused heterocyclic structures starting from readily available materials.

Preparation of CIP@TiO_(2) composite with broadband electromagnetic wave absorption properties

Scholars aim for the improved impedance matching (Z) of materials while maintaining their excellent wave absorption properties. Based on the hydrolysis characteristics of isopropyl titanate, a simple preparation process for the coating of carbonyl iron powder(CIP) with TiO_(2) was designed. Given the TiO2coating, the Z of the CIP@TiO_(2) composite was adjusted well by decreasing the dielectric constant. Moreover, the interfacial polarization of CIP@TiO_(2) was enhanced. Ultimately, the electromagnetic-wave (EMW) absorption property of the CIP@TiO_(2)composite was improved substantially, the minimum reflection loss reached-46.07 dB, and the effective absorption bandwidth can reach 8 GHz at the composite thickness of 1.5 mm. Moreover, compared with CIP, the oxidation resistance of CIP@TiO_(2)showed remarkable improvement. The results revealed that the oxidation starting temperature of CIP@TiO_(2) as about 400℃,whereas the uncoated CIP had an oxidation starting temperature of approximately 250℃. Moreover, the largest oxidation rate temperature of CIP@TiO_(2) increased to around 550℃. This work opens up a novel strategy for the production of high-performance EMW absorbers via structural design.

构筑开放锡位点实现酸性增强的二甲醚羰基化丝光沸石催化剂设计

Due to their tunable acidity,shape selectivity,and excellent stability,zeolites are of great importance as solid acid materials in industrial catalysis.Tuning the properties of the acid sites in zeolites allows for the rational design and fabrication of catalysts for target reactions.Dimethyl ether(DME)carbonylation,a critical chain-growth reaction for C1 resource utilization,is selectively catalyzed by the Brønsted acid sites within the eight-membered rings(8-MRs)of mordenite(MOR).It is anticipated that strengthening the Brønsted acidity—particularly in 8-MRs—will improve the catalytic performance of MOR.In this work,density functional theory(DFT)calculations are first employed and the results used to design a modified MOR with stannum(Sn)and to predict the corresponding changes in acidity.Guided by the theoretical studies,a series of Sn-modified MOR are synthesized via a defect-engineering and subsequent heteroatom-substitution strategy.After partial desilication,isolated tetrahedral Sn species in an open configuration are successfully synthesized for the first time,within which tetrahedrally coordinated Al sites are preserved.An acidic characterization is used to confirm that the acidity of the Brønsted acid sites is enhanced by the introduction of the Sn species;as a result,the sample exhibits excellent activity in DME carbonylation reaction.Kinetic and DFT studies reveal that this strengthened acidity facilitates the adsorption of DME and reduces the activation barriers of DME dissociation and acetyl formation,accounting for the improved activity.The work demonstrates mechanistic insights into the promoting effects of strong acidity on DME carbonylation and offers a promising strategy to precisely control the acidic strength of zeolites.

Copper-Catalyzed Carbonylative Synthesis of β-Boryl Amides via Boroamidation of Alkenes

β-Boryl amide is a class of high value intermediates in organic chemistry.In this work,a copper-catalyzed carbonylative boroamidation of olefins toward the synthesize ofβ-boryl amides has been developed.Several new chemical bonds were constructed in this transformation.A wide range ofβ-boryl amides were produced in excellent regioselectivity and good to excellent yields.Ethylene gas can be successfully transformed under the same standard conditions as well.Notably,with the use of a chiral ligand,the first example of enantioselective carbonylative boroamidation of alkenes was realized.In addition,Piposulfan and Pipobroman,antineoplastic medicines,were prepared by this methodology in a straightforward manner.

Synthesis of mordenite by solvent-free method and its application in the dimethyl ether carbonylation reaction

Mordenite with different Si/Al ratios were synthesized by solvent-free method and used for dimethyl ether(DME)carbonylation reaction.The influence of Si/Al ratio in the feedstock on the structure,porosity and acid sites were systematically investigated.The characterization results showed that with the increase of Si/Al ratio in the feedstock,part of silicon species fail to enter the skeleton and the specific surface area and pore volume of the samples decreased.The amount of weak acid and medium strong acid decreased alongside with the increasing Si/Al ratio,and the amount of strong acid slightly increased.The Al atoms preferentially enter the strong acid sites in the 8 member ring(MR)channel during the crystallization process.The high Si/Al ratio sample had more acid sites located in the 8 MR channel,leading to more active sites for carbonylation reaction and higher catalytic performance.Appropriately increasing the Si/Al ratio was beneficial for the improvement of carbonylation reaction activity over the mordenite(MOR)catalyst.

Excitation and ionization of OCS molecules in strong UV and NIR laser fields

Rydberg state excitation(RSE) is a highly non-linear physical phenomenon that is induced by the ionization of atoms or molecules in strong femtosecond laser fields. Here we observe that both parent and fragments(S, C, OC) of the triatomic molecule carbonyl sulfide(OCS) can survive strong 800 nm or 400 nm laser fields in high Rydberg states. The dependence of parent and fragment RSE yields on laser intensity and ellipticity is investigated in both laser fields, and the results are compared with those for strong-field ionization. Distinctly different tendencies for laser intensity and ellipticity are observed for fragment RSE compared with the corresponding ions. The mechanisms of RSE and strong-field ionization of OCS molecules in different laser fields are discussed based on the experimental results. Our study sheds some light on the strong-field excitation and ionization of molecules irradiated by femtosecond NIR and UV laser fields.

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.

Highly dispersed MgInCe-mixed metal oxides catalyzed direct carbonylation of glycerol and CO_(2)into glycerol carbonate

Glycerol carbonate,an important glycerol value-added product,has been widely used as an active intermediate and inert solvent in the synthesis of cosmetics,detergents,chemical intermediates,polymers,and so on.The direct carbonylation from glycerol with CO_(2)is considered a promising route,but still tough work due to the thermodynamic stability and the kinetic inertness of CO_(2).In this work,highlyselective direct carbonylation of glycerol and CO_(2)into glycerol carbonate has been achieved over highly dispersed MgInCe-mixed metal oxides(MgInCe-MMO),which were prepared through the topological transformation derived from the MgInCe-layered double hydroxides(MgInCe-LDHs).By precisely modulating the surface basic-acidic properties and the oxygen vacancies,an efficient carbonylation of glycerol with CO_(2)has been achieved with a selectivity of up to>99%to glycerol carbonate.Deep investigation into the synergistic catalysis of base-acid sites and oxygen vacancies has been clarified.

Facile synthesis of isoindoline-l,3-diones by palladium-catalyzed carbonylative cyclization of o-bromobenzoic acid and primary amines

A facile method for the carbonylative cycliza- tion of o-bromobenzoic acid with primary amine using Pd（OAC）2 as a metal precursor and 1, l′-bis（diphenylpho- sphino）ferrocene （dppf） as a ligand has been developed. The effect of various reaction parameters such as ligand, solvent, base, time and temperature on this cyclization was studied. The optimized protocol was used for a wide variety of substituted aryl amines with different steric and electronic properties, affording the corresponding isoindoline-l,3-diones in good to excellent yields under atmospheric pressure of carbon monoxide at 100℃ within 10h using 1,4-diazabicyclo[2.2.2]octane （DABCO） as a base. The reaction system finds attractive alternative to the conventional multistep synthetic process and thus repre- sents an effective utilization of carbonylative protocol for synthesis of valuable chemicals.

Palladium-Catalyzed Tandem Carbonylative Aza-Wacker-Type Cyclization of Nucleophile Tethered Alkene to Access Fused N-Heterocycles

Although tandem reactions offer rapid access to structurally complex molecules in one-pot reaction,the selectivity issue needs to be addressed particularly when incompatible step reactions are involved.Herein,we report the selective synthesis of fused N-heterocycles from nucleophile-tethered alkenylamide and carbon monoxide via palladium(Pd)-catalyzed tandem carbonylative aza-Wacker-type cyclization.The electron-deficient nature of amide N—H and the intramolecular coordination of Pd with alkene accelerate the aminopalladation and effectively prevent the side oxidative carbonylation of diamine moiety to form urea.It is also found that the reported acyl Pd chloride intermediate may not be involved in this tandem cyclization.This work not only provides an efficient synthetic route to fused 1,4-diazepanones and 1,4-diazepanes but also inspires further development of tandem reactions for the diverse synthesis of heterocycles.

Iron-catalyzed decarboxylative and oxidative decarbonylative cross-coupling:a new strategy for the synthesis of monofluoroalkenes

Herein,an iron(II)-catalyzed decarboxylative and oxidative decarbonylative cross-coupling ofα-fluoro cinnamic acids with aliphatic aldehydes is presented.This methodology provided a novel and practical strategy for the construction of monofluoroalkenes from abundant and readily available aliphatic aldehydes,which are key functional groups in used in synthetic transformations in the pharmaceutical and agrochemical sciences.

Cu/Pd-catalyzed borocarbonylative trifunctionalization of alkynes and allenes:synthesis ofβ-geminal-diboryl ketones

Functionalized bisboryl compounds have recently emerged as a new class of synthetically useful building blocks in organic synthesis.Herein,we report an efficient strategy to synthesizeβ-geminal-diboryl ketones enabled by a Cu/Pd-catalyzed borocarbonylative trifunctionalization of readily available alkynes and allenes.This reaction promises to be a useful method for the synthesis of functionalizedβ-geminal-diboryl ketones with broad functional group tolerance.Mechanistic studies suggest that the reaction proceeds through borocarbonylation/hydroboration cascade of both alkynes and allenes.

Palladium-catalyzed decarbonylative methylation of aryl carboxylic acids

Described herein is a palladium-catalyzed decarbonylative methylation of aryl carboxylic acids using tri-methylboroxine(TMB)as the methylating reagent.The Pd(OAc)_(2)/XantPhos system is compatible with a wide range of carboxylic acids and derivatives including aroyl chloride/fluoride.The successful methylation of bio-active molecules and examples of orthogonal cross-couplings demonstrate the practicality of this method.