The use of gaseous CO in Pd-catalyzed carbonylative quinolone synthesis presents challenges related to safety and precise pressure control. In response, a streamlined non-gaseous synthesis of ...4-quinolone compounds has been developed. This study introduces a tunable CO-releasing system utilizing Fe(CO)sub.5 activated by a dual-base system of piperazine and triethylamine. This alternative liquid CO resource facilitates the palladium-catalyzed carbonylative C-C coupling and subsequent intramolecular cyclization. By tuning the tandem kinetics of carbonylation and cyclization, this non-gaseous method achieves the successful synthesis of 22 distinct 4-quinolones with excellent yields. This is achieved through the three-component condensation of sub-stoichiometric amounts of Fe(CO)sub.5 with 2-iodoaniline and terminal alkynes. Operando mechanistic studies have revealed a novel CO transfer mechanism that facilitates homogeneous carbonylative cyclization, distinguishing this method from traditional techniques. In addition to addressing safety concerns, this approach also provides precise control over selectivity, with significant implications for pharmaceutical research and the efficient synthesis of pharmaceutical and bioactive compounds.
Palladium-catalyzed direct (het)arylation reactions of strongly electron-withdrawing tricyclic benzo1,2-d:4,5-d′bis(1,2,3thiadiazole) and its 4,8-dibromo derivative were studied; the conditions for ...the selective formation of mono- and bis-aryl derivatives were found. The reaction of 4,8-dibromobenzo1,2-d:4,5-d′bis(1,2,3thiadiazole) with thiophenes in the presence of palladium acetate as a catalyst and potassium pivalate as a base, depending on the conditions used, selectively gave both mono- and bis-thienylated benzo-bis-thiadiazoles in low to moderate yields; arenes were found to be inactive in these reactions. It was discovered that direct C–H arylation of benzo1,2-d:4,5-d′bis(1,2,3thiadiazole with bromo(iodo)arenes and -thiophenes in the presence of Pd(OAc)2 and di-tert-butyl(methyl)phosphonium tetrafluoroborate salt is a powerful tool for the selective formation of 4-mono- and 4,8-di(het)arylated benzo-bis-thiadiazoles. Oxidative double C–H hetarylation of benzo1,2-d:4,5-d′bis(1,2,3thiadiazole with thiophenes in the presence of Pd(OAc)sub.2 and silver (I) oxide in DMSO was successfully employed to prepare bis-thienylbenzo-bis-thiadiazoles in moderate yields.
2D field-effect transistors (FETs) fabricated with transition metal dichalcogenide (TMD) materials are a potential replacement for the silicon-based CMOS. However, the lack of advancement in p-type ...contact is also a key factor hindering TMD-based CMOS applications. The less investigated path towards improving electrical characteristics based on contact geometries with low contact resistance (R sub.C) has also been established. Moreover, finding contact metals to reduce the R sub.C is indeed one of the significant challenges in achieving the above goal. Our research provides the first comparative analysis of the three contact configurations for a WSesub.2 monolayer with different noble metals (Rh, Ru, and Pd) by employing ab initio density functional theory (DFT) and non-equilibrium Green’s function (NEGF) methods. From the perspective of the contact topologies, the R sub.C and minimum subthreshold slope (SS sub.MIN) of all the conventional edge contacts are outperformed by the novel non-van der Waals (vdW) sandwich contacts. These non-vdW sandwich contacts reveal that their R sub.C values are below 50 Ω∙μm, attributed to the narrow Schottky barrier widths (SBWs) and low Schottky barrier heights (SBHs). Not only are the R sub.C values dramatically reduced by such novel contacts, but the SS sub.MIN values are lower than 68 mV/dec. The new proposal offers the lowest R sub.C and SS sub.MIN, irrespective of the contact metals. Further considering the metal leads, the WSesub.2/Rh FETs based on the non-vdW sandwich contacts show a meager R sub.C value of 33 Ω∙μm and an exceptional SS sub.MIN of 63 mV/dec. The two calculated results present the smallest-ever values reported in our study, indicating that the non-vdW sandwich contacts with Rh leads can attain the best-case scenario. In contrast, the symmetric convex edge contacts with Pd leads cause the worst-case degradation, yielding an R sub.C value of 213 Ω∙μm and an SS sub.MIN value of 95 mV/dec. While all the WSesub.2/Ru FETs exhibit medium performances, the minimal shift in the transfer curves is interestingly advantageous to the circuit operation. Conclusively, the low-R sub.C performances and the desirable SS sub.MIN values are a combination of the contact geometries and metal leads. This innovation, achieved through noble metal leads in conjunction with the novel contact configurations, paves the way for a TMD-based CMOS with ultra-low R sub.C and rapid switching speeds.
Mixed ligand complexes of Pd(II) and Cd(II) with N-picolyl-amine dithiocarbamate (PAC-dtc) as primary ligand and tertiary phosphine ligand as secondary ligands have been synthesized and characterized ...via elemental analysis, molar conductance, NMR (sup.1H and sup.31P), and IR techniques. The PAC-dtc ligand displayed in a monodentate fashion via sulfur atom whereas diphosphine ligands coordinated as a bidentate mode to afford a square planner around the Pd(II) ion or tetrahedral around the Cd(II) ion. Except for complexes Cd(PAC-dtc)sub.2(dppe) and Cd(PAC-dtc)sub.2(PPhsub.3)sub.2, the prepared complexes showed significant antimicrobial activity when evaluated against Staphylococcus aureus, Pseudomonas aeruginosa, Candida albicans and Aspergillus niger. Moreover, DFT calculations were performed to investigate three complexes {Pd(PAC-dtc)sub.2(dppe)(1), Cd(PAC-dtc)sub.2(dppe)(2), Cd(PAC-dtc)sub.2(PPhsub.3)sub.2(7)}, and their quantum parameters were evaluated using the Gaussian 09 program at the B3LYP/Lanl2dz theoretical level. The optimized structures of the three complexes were square planar and tetrahedral geometry. The calculated bond lengths and bond angles showed a slightly distorted tetrahedral geometry for Cd(PAC-dtc)sub.2(dppe)(2) compared to Cd(PAC-dtc)sub.2(PPhsub.3)sub.2(7) due to the ring constrain in the dppe ligand. Moreover, the Pd(PAC-dtc)sub.2(dppe)(1) complex showed higher stability compared to Cd(2) and Cd(7) complexes which can be attributed to the higher back-donation of Pd(1) complex.
We report herein on a catalytic system involving palladium and copper to achieve the cyclization of N-arylcyanothioformamides and the synthesis of 2-cyanobenzothiazoles. The C-H ...functionalization/intramolecular C-S bond formation reaction was achieved in the presence of air, using 2.0 equiv of an inorganic additive (KI). In many cases, the reaction led to a sole product regioselectively obtained in good yields, allowing the synthesis of a wide range of substituted 2-cyanobenzothiazole derivatives, providing valuable building blocks for the design of more complex heterocyclic or molecular labeling systems.
A novel protocol facilitated by Nasub.2SOsub.3 that enhances the efficiency of palladium-catalyzed Heck coupling and the homo-coupling reactions of arylhydrazines. This innovative method enables the ...effective construction of a diverse array of cinnamate derivatives and biphenyl compounds. Notably, these transformative reactions proceed smoothly at room temperature, leveraging the activation of C-N bonds. This technique not only streamlines the synthesis process but also expands our understanding and expertise in the realm of coupling reactions.
Many studies have been conducted on the microbial reduction of Pd (II) to palladium nanoparticles (Pd-NPs) due to the environmental friendliness, low cost, and the decreased toxicity of Pd (II) ions. ...In this study, we investigate the reduction mechanism of Pd (II) by Bacillus megaterium Y-4 through proteomics. The data are available via ProteomeXchange with identifier PXD049711. Our results revealed that B. megaterium Y-4 may use the endogenous electron donor (NAD(P)H) generated by nirB, tdh, and fabG and reductase to reduce Pd (II) to Pd-NPs. The expression levels of fabG, tdh, gudB, and rocG that generate NAD(P)H were further increased, and the number of reduced Pd-NPs was further increased with the exogenous electron donor sodium formate. Endogenous electron mediators such as quinones and flavins in B. megaterium Y-4 can further enhance Pd (II) reduction. The findings provided invaluable information regarding the reduction mechanism of Pd (II) by B. megaterium Y-4 at the proteome level.
Palladium phosphonium complexes with mononuclear anions Ph.sub.3PCH.sub.2CNPdBr.sub.4, Ph.sub.4PPdBr.sub.4, and Ph.sub.3PC.sub.5H.sub.9-cycloPdBr.sub.3(Et.sub.2SO) were synthesized by the reaction of ...organyltriphenylphosphonium bromides with palladium(II) bromide in the presence of hydrobromic acid followed by recrystallization from acetonitrile, dimethyl sulfoxide, or diethyl sulfoxide. Holding the Ph.sub.4PPdBr.sub.4 complex in acetonitrile with the addition of diamyl sulfoxide led to the formation of the Ph.sub.4P.sub.2Pd.sub.2Br.sub.6 complex. According to single crystal X-ray diffraction analysis, mononuclear PdBr.sub.4.sup.2-, PdBr.sub.3(Et.sub.2SO).sup.- and binuclear Pd.sub.2Br.sub.6.sup.2- anions in the complexes have a planar structure.
![Na[sub.2]SO[sub.3]-Promoted...](http://api.summon.serialssolutions.com/2.0.0/image/issn/XR4PS5YY4K/2073-4344/small "Na[sub.2]SO[sub.3]-Promoted Heck Coupling and Homo-Coupling of Arylhydrazines at Room Temperature")
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