Traditional Wacker-type oxidations of unbiased alkenes produce ketones as major products. Recently, Grubbs’ group reported a Wacker-type oxidation system in which aldehydes (rather than ketones) have been generated predominantly in the presence of a nitrite co-catalyst. To elucidate the mechanistic origin of the aldehyde selectivity, density functional theory (DFT) studies have been conducted in this study. Two oxymetalation pathways, i.e., syn addition and anti addition pathways, were considered for various possible active species including monomeric Pd, bimetallic Pd−Pd, heterobimetallic Pd−Cu, and heterobimetallic Pd−Ag complexes. It is found that syn addition is kinetically more favored than anti addition in general. Meanwhile, the most feasible oxymetalation processes occur on the heterobimetallic Pd−Cu complexes. Investigations on the subsequent aldehyde formation process show that 1,2-H shift mechanism on tBuOH-ligated Pd−Cu complexes is superior to the betaH-elimination mechani

Trifluoromethylation reactions are important transformations in the research and development of drugs, agrochemicals and functional materials. An oxidation/reduction process of trifluoromethyl-containing compounds is thought to be involved in many recently tested catalytic trifluoromethylation reactions. To provide helpful physical chemical data for mechanistic studies on trifluoromethylation reactions, the redox potentials of a variety of trifluoromethyl-containing compounds and trifluoromethylated radicals were studied by quantum-chemical methods. First, wB97X-D was found to be a reliable method in predicting the ionization potentials, electron affinities, bond dissociation enthalpies and redox potentials of trifluoromethylcontaining compounds. One-electron absolute redox potentials of 79 trifluoromethyl substrates and 107 trifluoromethylated radicals in acetonitrile were then calculated with this method. The theoretical results were found to be helpful for interpreting experimental

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

Here, an unpresented non-C1 synthon function of CO2 is reported to facilitate electrochemical defluorination. The introduction of CO2 modulates the electron distribution of the radical anion intermediate generated through one-electron reduction, thereby weakening the reduction potential and facilitating reduction and defluorination. CO2 is released subsequently via spontaneous decarboxylation to complete its promotion role. The presented results shed light on a distinctive utilization of CO2, which may stimulate interest in developing non-C1 synthon functions of CO2.

A KOtBu-mediated C2-benzylation of quinoline N-oxides with benzylboronates under mild reaction conditions has been developed. The reaction shows broad scope for both of the quinoline N-oxides and benzylboronates, especially, secondary and tertiary benzylboronates are also compatible with this reaction. DFT calculations indicate that the reaction is promoted by the nucleophilic addition of KOtBu to boronate rather than the deprotonation of benzylic C−H bond with KOtBu.

A 1,1-hydroboration of alkynylgermanes with unique transGe/B stereochemistry under transition-metal-free conditions is reported. Mechanistic studies suggest that a pathway involving α boration followed by a stepwise 1,2-Ge/H shift on the intermediate structurally lies between an alkyne−Ge+ π complex and a typical vinyl cation. The resulting Ge/B bimetallic modules, along with a Ge*/Ge/B trimetallic variant, can be conveniently transformed into trisubstituted olefins through iterative divergent cross-coupling. This work demonstrates that incorporating metalloids into classical organic reactions may offer unconventional chemical selectivity and efficient synthetic applications.

Nickel/photoredox dual catalyzed cross-coupling of aryl halides with alkylboron compounds is one of the effective methodologies for the construction of C(sp2) C(sp3) bonds. Although elegant results have been achieved by using alkyl trifluoroborates as alkyl radical precursors, the generation of alkyl radicals from readily available alkyl boronic esters is still limited due to their high oxidation potential. We disclosed here that activation of alkyl boronic esters by MeOLi is highly efficient for the generation of alkyl radicals under photocatalysis conditions. The reaction featured with a wide substrate scope, high functional group tolerance, and late-stage modification of bioactive substances. In addition, the method was also successfully extended to alkyl boronic acids. Experimental and computational mechanistic studies indicated that the crosscoupling likely proceeds via a Ni(I)-catalyzed pathway.

Here, an unpresented non-C1 synthon function of CO2 is reported to facilitate electrochemical defluorination. The introduction of CO2 modulates the electron distribution of the radical anion intermediate generated through one-electron reduction, thereby weakening the reduction potential and facilitating reduction and defluorination. CO2 is released subsequently via spontaneous decarboxylation to complete its promotion role. The presented results shed light on a distinctive utilization of CO2, which may stimulate interest in developing non-C1 synthon functions of CO2.

A KOtBu-mediated C2-benzylation of quinoline N-oxides with benzylboronates under mild reaction conditions has been developed. The reaction shows broad scope for both of the quinoline N-oxides and benzylboronates, especially, secondary and tertiary benzylboronates are also compatible with this reaction. DFT calculations indicate that the reaction is promoted by the nucleophilic addition of KOtBu to boronate rather than the deprotonation of benzylic C−H bond with KOtBu.

A 1,1-hydroboration of alkynylgermanes with unique transGe/B stereochemistry under transition-metal-free conditions is reported. Mechanistic studies suggest that a pathway involving α boration followed by a stepwise 1,2-Ge/H shift on the intermediate structurally lies between an alkyne−Ge+ π complex and a typical vinyl cation. The resulting Ge/B bimetallic modules, along with a Ge*/Ge/B trimetallic variant, can be conveniently transformed into trisubstituted olefins through iterative divergent cross-coupling. This work demonstrates that incorporating metalloids into classical organic reactions may offer unconventional chemical selectivity and efficient synthetic applications.

Nickel/photoredox dual catalyzed cross-coupling of aryl halides with alkylboron compounds is one of the effective methodologies for the construction of C(sp2) C(sp3) bonds. Although elegant results have been achieved by using alkyl trifluoroborates as alkyl radical precursors, the generation of alkyl radicals from readily available alkyl boronic esters is still limited due to their high oxidation potential. We disclosed here that activation of alkyl boronic esters by MeOLi is highly efficient for the generation of alkyl radicals under photocatalysis conditions. The reaction featured with a wide substrate scope, high functional group tolerance, and late-stage modification of bioactive substances. In addition, the method was also successfully extended to alkyl boronic acids. Experimental and computational mechanistic studies indicated that the crosscoupling likely proceeds via a Ni(I)-catalyzed pathway.