(DMP)DAB–Pd–MAH: A Versatile Pd(0) Source for Precatalyst Formation, Reaction Screening, and Preparative-Scale Synthesis

We report an easily prepared and bench-stable mononuclear Pd(0) source stabilized by a chelating <i>N</i>,<i>N</i>’-diaryldiazabutadiene ligand and maleic anhydride: ^DMPDAB–Pd–MAH. Phosphine ligands of all types, including bidentate phosphines and large cone angle biarylphosphines, rapidly and completely displace the diazabutadiene ligand at room temperature to give air-stable Pd(0) phosphine complexes. ^DMPDAB–Pd–MAH itself is readily soluble and stable in several organic solvents, making it an ideal Pd source for <i>in situ</i> catalyst preparation during reaction screening, as well as solution-dispensing to plate-based reaction arrays for high-throughput experimentation. Evaluation of ^DMPDAB–Pd–MAH alongside other common Pd(0) and Pd(II) sources in microscale reaction screens reveals that ^DMPDAB–Pd–MAH is superior at identifying hits across six different C–N, C–C, and C–O coupling reactions. ^DMPDAB–Pd–MAH, and the phosphine precatalysts derived therefrom, are also effective in preparative-scale cross couplings at low Pd loadings.

(DMP)DAB–Pd–MAH: A Versatile Pd(0) Source for Precatalyst Formation, Reaction Screening, and Preparative-Scale Synthesis

We report an easily prepared and bench-stable mononuclear Pd(0) source stabilized by a chelating <i>N</i>,<i>N</i>’-diaryldiazabutadiene ligand and maleic anhydride: ^DMPDAB–Pd–MAH. Phosphine ligands of all types, including bidentate phosphines and large cone angle biarylphosphines, rapidly and completely displace the diazabutadiene ligand at room temperature to give air-stable Pd(0) phosphine complexes. ^DMPDAB–Pd–MAH itself is readily soluble and stable in several organic solvents, making it an ideal Pd source for <i>in situ</i> catalyst preparation during reaction screening, as well as solution-dispensing to plate-based reaction arrays for high-throughput experimentation. Evaluation of ^DMPDAB–Pd–MAH alongside other common Pd(0) and Pd(II) sources in microscale reaction screens reveals that ^DMPDAB–Pd–MAH is superior at identifying hits across six different C–N, C–C, and C–O coupling reactions. ^DMPDAB–Pd–MAH, and the phosphine precatalysts derived therefrom, are also effective in preparative-scale cross couplings at low Pd loadings.

High-Throughput Discovery and Evaluation of a General Catalytic Method for N-Arylation of Weakly Nucleophilic Sulfonamides

Sulfonamides are poor nucleophiles in Pd C-N coupling catalysis, hindering synthesis of densely-functionalized N,N-diaryl sulfonamide motifs relevant to medicinal chemistry. Through targeted high-throughput experimentation (HTE), we have identified the Pd/AdBippyPhos catalyst system as an effective and general method to construct this difficult to access moiety. In particular, AdBippyPhos is critical for the installation of heteroaromatic groups. Computational steric parameterization of the investigated ligands reveals the potential importance of remote steric demand, where a large cone angle combined with an accessible Pd center is correlated to successful catalysts for C-N coupling reactions.<br>

High-Throughput Discovery and Evaluation of a General Catalytic Method for N-Arylation of Weakly Nucleophilic Sulfonamides

Sulfonamides are poor nucleophiles in Pd C-N coupling catalysis, hindering synthesis of densely-functionalized N,N-diaryl sulfonamide motifs relevant to medicinal chemistry. Through targeted high-throughput experimentation (HTE), we have identified the Pd/AdBippyPhos catalyst system as an effective and general method to construct this difficult to access moiety. In particular, AdBippyPhos is critical for the installation of heteroaromatic groups. Computational steric parameterization of the investigated ligands reveals the potential importance of remote steric demand, where a large cone angle combined with an accessible Pd center is correlated to successful catalysts for C-N coupling reactions.<br>

AdBippyPhos Promotes Pd-Catalyzed C–N Coupling Between Weakly Nucleophilic Sulfonamides and Heteroaryl Halides

Sulfonamides are poor nucleophiles in Pd C-N coupling catalysis, hindering synthesis of densely-functionalized N,N-diaryl sulfonamide motifs relevant to medicinal chemistry. Through targeted high-throughput experimentation (HTE), we have identified the Pd/AdBippyPhos catalyst system as an effective and general method to construct this difficult to access moiety. In particular, AdBippyPhos is critical for the installation of heteroaromatic groups. Computational steric parameterization of the investigated ligands reveals the potential importance of remote steric demand, where a large cone angle combined with an accessible Pd center is correlated to successful catalysts for C-N coupling reactions.<br>

Effects of Additional Body on Jet Velocity of Hyper-cumulation

In this paper, with different cone angles of the liner, the effects of the additional body’s material, thickness, and diameter on the velocity are studied by AUTODYN-2D. The results show as follows: 1. The additional body can increase the top velocity of the jet but has little effect on the tail velocity. 2. When the cone angle is larger, the velocity increases more, about 36%, and the velocity gradient is greater at the head of the jet. 3. There is little influence of material yield strength, but there is a large correlation with density. With the increase of material density, the velocity and velocity gradient increase. 4. The larger the density of the additional body, the smaller the optimum thickness. When the thickness is not less than the optimum thickness, an increase in the diameter of the additional body can improve the velocity and stability of the jet. Consequently, this kind of hyper-cumulation structure with a flat plate additional body is more suitable to improve the classical liner with a large cone angle. By modifying the design of the shaped charge in this way, the velocity of the jet can be improved effectively, enhancing the penetration power compared with the classical one.

Evaluation of Algebraic Iterative Image Reconstruction Methods for Tetrahedron Beam Computed Tomography Systems

Tetrahedron beam computed tomography (TBCT) performs volumetric imaging using a stack of fan beams generated by a multiple pixel X-ray source. While the TBCT system was designed to overcome the scatter and detector issues faced by cone beam computed tomography (CBCT), it still suffers the same large cone angle artifacts as CBCT due to the use of approximate reconstruction algorithms. It has been shown that iterative reconstruction algorithms are better able to model irregular system geometries and that algebraic iterative algorithms in particular have been able to reduce cone artifacts appearing at large cone angles. In this paper, the SART algorithm is modified for the use with the different TBCT geometries and is tested using both simulated projection data and data acquired using the TBCT benchtop system. The modified SART reconstruction algorithms were able to mitigate the effects of using data generated at large cone angles and were also able to reconstruct CT images without the introduction of artifacts due to either the longitudinal or transverse truncation in the data sets. Algebraic iterative reconstruction can be especially useful for dual-source dual-detector TBCT, wherein the cone angle is the largest in the center of the field of view.

Closed Hot Precision Forging Process of a Bevel Gear with Large Cone Angle

The closed hot precision forging process of a bevel gear with large cone angle was studied. According to the structure features of the bevel gear, two types of relief forging processes were proposed. First, simulations based on thermal-mechanical coupling finite element model were performed with Deform3D. Then the corresponding experiments were conducted and the results perfectly matched the simulation results. The advantages and deficiencies of two processes were discussed and a reliable basis for selecting the optimal process was proposed.