Density functional theory (DFT) method was used to explore the origin of the regioselectivity of Cocatalyzed hydroacylation of 1,3-dienes. The reaction of 2-methyl-1,3-butadiene and benzaldehyde with 1,3-bis(diphenylphosphino)propane ligand was chosen as the model reaction. The energies of the intermediates and transition states in the stages of oxidative cyclization, b-H elimination and C-H reductive elimination were investigated. Computational results show that b-H elimination is the ratedetermining step for the whole catalytic cycle. C1-Selective oxidative cyclization is favored over C4- selective oxidative cyclization. Besides, C4-selective oxidative cyclization is kinetically disfavored than all the steps in C1-hydroacylation mechanisms, consistent with the experimentally obtained C1- selective hydroacylation products. Analyzing the reason for such observation, we suggest that both electronic and steric effects contribute to the C1-selectivity. On the electronic aspect, C1 is more

In this study we demonstrate that indoles can be directly produced by thermo-catalytic conversion of bio-derived furans with ammonia over zeolite catalysts. MCM-41, β-zeolite, ZSM-5 (Si/Al = 50) and HZSM-5 catalysts with different Si/Al ratios (Si/Al = 25, 50, 63, 80) were screened and HZSM-5 with an Si/Al ratio of 25 showed the best reactivity for indole production due to the desired pore structure and acidity. Temperature displayed a significant effect on the product distribution. The maximum yield of indoles was obtained at moderate temperatures around 500 °C. The weight hourly space velocity (WHSV) of furan to catalyst investigation indicated that a lower WHSV could cause the overreaction of furan over the catalyst to produce more aniline and pyridines, while a higher WHSV would cause the incomplete reaction of furan. Because ammonia served as both a reactant and a carrier gas, to supply sufficient reactants and keep the desired reaction time, an appropriate ammonia to furan molar

The Ni-catalyzed C(sp2)¢H/C(sp3)¢H coupling of benzamides with toluene derivatives was recently successfully achieved with mild oxidant iC3F7I. Herein, we employ density functional theory (DFT) methods to resolve the mechanistic controversies. Two previously proposed mechanisms are excluded, and our proposed mechanism involving iodine-atom transfer (IAT) between iC3F7I and the NiII intermediate was found to be more feasible. With this mechanism, the presence of a carbon radical is consistent with the experimental observation that (2,2,6,6-tetramethylpiperidin- 1-yl)oxyl (TEMPO) completely quenches the reaction. Meanwhile, the hydrogen-atom abstraction of toluene is irreversible and the activation of the C(sp2)¢H bond of benzamides is reversible. Both of these conclusions are in good agreement with Chatani’s deuterium-labeling experiments.

Recently, the Li group reported the first Ag-catalyzed hydrogenation of aldehydes in water, demonstrating the utility of Ag complexes in homogeneous catalytic transformations through hydrogen activation. In the present study, density functional theory methods have been used to study the mechanism of Ag-catalyzed hydrogen activation. Three possible pathways, including base-assisted hydrogen activation, ligand-assisted hydrogen activation, and oxidative addition were investigated. The ligand-assisted hydrogen activation is disfavored because the neutral biaryl phosphine ligand XPhos is not a competent proton acceptor and results in the destruction of the aromaticity of an aryl group. Oxidative addition of H2 on AgI complexes was also found to be unlikely. The resulting AgIII hydride complexes are highly unstable and can undergo spontaneous reduction due to the weakly electron-donating ligand and the relatively low electronegativity of hydrogen. By contrast, the base-assisted hydrogen act

Flavin-dependent catalysts are widely applied to aerobic monooxygenation/oxidation reactions. In contrast, flavin-catalyzed aerobic dioxygenation reactions exhibit higher atomic economy but are less reported, not to mention the relevant mechanistic studies. Herein, a density functional theory study on flavin-catalyzed aerobic epoxidation-oxygenolysis of alkenyl thio-esters was performed for the first time. Different from the previous mechanistic proposal, a pathway featuring two catalytic stages, monoanionic flavin-C(4a)-peroxide/oxide intermediates, and a reverse reaction sequence (epoxidation goes prior to oxygenolysis) was revealed. In comparison, the pathways involving dianionic flavin catalysts, monoanionic flavin-N(5)-(hydro)peroxide/C-(10a)-peroxide, or neutral flavin-C(4a)-hydroperoxide/hydroxide/N(5)-oxide, and the pathways where oxygenolysis goes prior to epoxidation are less favored. Epoxidation goes through intramolecular substitution of the O−O bond of anionic flavin-C(4a)

DFT calculations are carried out to investigate the hydroacylation mechanism based on copper-catalyzed A3- coupling tandem reaction of terminal alkynes, aldehydes and amines. The study reveals significant mechanistic differences between copper(I) and copper(II) catalysts. In the Cu(II)-catalyzed system, incorporation of a ligand is deemed necessary for facilitating reactivity, whereas no ancillary ligand is required in Cu(I) system. The ligand, through coordination with the Cu(II) center, stabilizes the key transition states and intermediates, resulting in a substantial reduction in the activation barrier. The ligand exhibits varying effect, with the order of activity being piperidine > pyridine > DMSO, correlating positively with the interaction energy between ligand and Cu complex. Additionally, the study sheds light on the pivotal roles played by the catalyst, ligand, base, and solvent DMSO in the reaction.

Developing applicable methods to forge linkages between sp3 and sp2-hydridized carbons is of great significance in drug discovery. We show here a new, Ni-catalyzed reductive crosscoupling reaction that forms Csp3−Csp2 bonds from aryl iodides and cyclic sulfonium salts. Notably, Csp3−Csp2 bonds can be forged selectively at the iodine-bearing carbon of bromo(iodo)arenes which is usually recognized as a huge challenge under the catalytic reductive cross-coupling (CRCC) conditions. Experimental and computational mechanistic studies support LNiIAr as an active species, while the untraditional anti-Markovnikov selective alkylation of asymmetric sulfonium salts is determined by the oxidative S-substitution of sulfonium salts with LNiIAr. This protocol further expands the range of alkyl electrophiles under the CRCC conditions and provides a new strategy for the construction of Csp3−Csp2 bonds.

An unprecedented transient promotion function (TPF) of CO2 in the electrochemical hydrogenation/deuteration of imines (especially α-iminonitriles) is reported. The TPF influence of CO2 results from the introduction of CO2 that disperses the negative charges of the imine radical anion intermediate. The resulting redistribution of electrons leads to a lower reduction potential of the CO2-substituted imine radical anion and thus facilitates the succeeding one-electron reduction. CO2 is finally released via spontaneous decarboxylation to complete the transient promotion process.

Flavin-dependent catalysts are widely applied to aerobic monooxygenation/oxidation reactions. In contrast, flavin-catalyzed aerobic dioxygenation reactions exhibit higher atomic economy but are less reported, not to mention the relevant mechanistic studies. Herein, a density functional theory study on flavin-catalyzed aerobic epoxidation-oxygenolysis of alkenyl thio-esters was performed for the first time. Different from the previous mechanistic proposal, a pathway featuring two catalytic stages, monoanionic flavin-C(4a)-peroxide/oxide intermediates, and a reverse reaction sequence (epoxidation goes prior to oxygenolysis) was revealed. In comparison, the pathways involving dianionic flavin catalysts, monoanionic flavin-N(5)-(hydro)peroxide/C-(10a)-peroxide, or neutral flavin-C(4a)-hydroperoxide/hydroxide/N(5)-oxide, and the pathways where oxygenolysis goes prior to epoxidation are less favored. Epoxidation goes through intramolecular substitution of the O−O bond of anionic flavin-C(4a)

DFT calculations are carried out to investigate the hydroacylation mechanism based on copper-catalyzed A3- coupling tandem reaction of terminal alkynes, aldehydes and amines. The study reveals significant mechanistic differences between copper(I) and copper(II) catalysts. In the Cu(II)-catalyzed system, incorporation of a ligand is deemed necessary for facilitating reactivity, whereas no ancillary ligand is required in Cu(I) system. The ligand, through coordination with the Cu(II) center, stabilizes the key transition states and intermediates, resulting in a substantial reduction in the activation barrier. The ligand exhibits varying effect, with the order of activity being piperidine > pyridine > DMSO, correlating positively with the interaction energy between ligand and Cu complex. Additionally, the study sheds light on the pivotal roles played by the catalyst, ligand, base, and solvent DMSO in the reaction.

Developing applicable methods to forge linkages between sp3 and sp2-hydridized carbons is of great significance in drug discovery. We show here a new, Ni-catalyzed reductive crosscoupling reaction that forms Csp3−Csp2 bonds from aryl iodides and cyclic sulfonium salts. Notably, Csp3−Csp2 bonds can be forged selectively at the iodine-bearing carbon of bromo(iodo)arenes which is usually recognized as a huge challenge under the catalytic reductive cross-coupling (CRCC) conditions. Experimental and computational mechanistic studies support LNiIAr as an active species, while the untraditional anti-Markovnikov selective alkylation of asymmetric sulfonium salts is determined by the oxidative S-substitution of sulfonium salts with LNiIAr. This protocol further expands the range of alkyl electrophiles under the CRCC conditions and provides a new strategy for the construction of Csp3−Csp2 bonds.

An unprecedented transient promotion function (TPF) of CO2 in the electrochemical hydrogenation/deuteration of imines (especially α-iminonitriles) is reported. The TPF influence of CO2 results from the introduction of CO2 that disperses the negative charges of the imine radical anion intermediate. The resulting redistribution of electrons leads to a lower reduction potential of the CO2-substituted imine radical anion and thus facilitates the succeeding one-electron reduction. CO2 is finally released via spontaneous decarboxylation to complete the transient promotion process.