Theoretical Studies on Rh-Catalyzed Cycloisomerization of Homopropargylallene-Alkynes through C(sp3)–C(sp) Bond Activation

Computational Mechanism Investigation of C=C Bond Hydrogenation Catalyzed by Rhodium Hydride

The hydrogenation of unsaturated carbons is a commonly used synthetic tool in pharmaceutical and industrial production. Recently, the Norton group realized highly selective hydrogenation of C=C bonds catalyzed by a rhodium hydride. Despite the great efforts made by experimentalists, details regarding the mechanism remained unclear. In this work, detailed DFT calculations were carried out to elucidate the principal features of this transformation. For enones we find that two possible competing mechanisms proposed by the experimental groups are computationally excluded, our proposed alternative mechanism with a total barrier of 20.0 kcal mol^-1 is theoretically feasible, solvent methanol to also plays a crucial role in assisting β-hydrogenation in addition to being the hydrogen source for α-hydrogenation, and the cross-polarization of the substrate enone-conjugated system to result in an enhanced charge density of the α-carbon, which favors being hydrogenated first. For isolated alkenes, neither of the two possible competing mechanisms can be excluded computationally and which carbon atom is first hydrogenated depends on the electronic properties of the substrate itself. The combination of rhodium and C=C bonds changes the electronic properties of H on the rhodium hydride and enhances its hydrogenation activity.

Advances in Catalytic C–F Bond Activation and Transformation of Aromatic Fluorides

The activation and transformation of C–F bonds in fluoro-aromatics is a highly desirable process in organic chemistry. It provides synthetic methods/protocols for the generation of organic compounds possessing single or multiple C–F bonds, and effective catalytic systems for further study of the activation mode of inert chemical bonds. Due to the high polarity of the C–F bond and it having the highest bond energy in organics, C–F activation often faces considerable academic challenges. In this mini-review, the important research achievements in the activation and transformation of aromatic C–F bond, catalyzed by transition metal and metal-free systems, are presented.

Mechanistic insights into nickel- and gold-catalyzed diastereoselective [4 + 2 + 1] cycloadditions between dienynes and diazo compounds: a DFT study

Density functional theory (DFT) calculations were performed to gain an in-depth mechanistic understanding of Ni(0)- and Au(i)-catalyzed diastereoselective [4 + 2 + 1] cycloadditions between dienynes and diazo compounds.

DFT study of Ni/NHC-catalyzed C–H alkylation of fluoroarenes with alkenes to synthesize fluorotetralins: mechanism, chemoselectivity of C–H vs. C–F bond activation, and regio- and enantioselectivities of C–H bond activation

DFT calculations clarified the mechanism of Ni/NHC-catalyzed C–H alkylation of alkene tethered fluoroarene and rationalized enantio-, regio- and chemoselectivities.

Theoretical study of rhodium(III)-catalyzed synthesis of benzoxepine and coumarin

The mechanisms of the rhodium-catalyzed cycloaddition of 2-vinylphenol with diphenylacetylene and carbon monoxide have been studied using density functional theory calculations at the B3LYP/6-31G (d, p) (Lanl2dz for Rh) level of theory. The SMD solvation model was used in MeCN solvents at M06-2X/6-311 ++ G (d, p) (Lanl2dz (f) for Rh) levels using a single-point calculation to consider the solvent effect. The calculation results show that there are two competitive reaction pathways for the cycloaddition reaction of rhodium-catalyzed synthesis of benzohexine and coumarin. Starting from the precursor reaction complex, the reaction channel is more favorable for the carbon atoms of diphenylacetylene and carbon monoxide to attack the Rh-C bond (the barriers of 9.88 and 10.01 kcal/mol) rather than attack the Rh-O bond (the barriers of 15.37 and 30.17 kcal/mol), and carbon monoxide in two different reaction channels has a greater energy difference than diphenylacetylene. The results show that the computational study of the rhodium-catalyzed cycloaddition reaction has a high catalytic activity consistent with the high yield of the experiment of Gulías et al.

A theoretical mechanistic study of IrIII/CuI-metallaphotoredox catalyzed asymmetric radical decarboxylative cyanation

The radical mechanism and origin of the high enantioselectivity of the photoredox-mediated Ir^III/Cu^I dual-catalyzed asymmetric decarboxylative cyanation have been theoretically disclosed.