A mechanistic investigation of α-alkynylation and α- allenylation of aldehydes under the synergistic catalysis of AuCl/ amine was performed using density functional theory (DFT) calculations. For such a reaction that delivers two products, this study reveals that the reaction undergoes such a mechanistic mode: reactants → alkynyl product → allenyl product, implying that the allenyl product cannot be obtained directly from reactants. The product ratio obtained experimentally was rationalized based on the computed results that both products can reversibly interconvert with AuCl as the catalyst and with N-containing Lewis bases as additives such as 4,5-diazafluorenone. For the relative stability of alkynyl versus allenyl compounds, unsaturated substituents are found to favor the allenyl compounds.

Density functional theory (DFT) calculations have been conducted to study the mechanisms, substituent effects, and the role of bases in Au- and Cu-catalyzed hydroacylation of terminal alkyne with glyoxal derivatives. The two reactions, despite being catalyzed by the same group of transition metals, follow distinctive reaction mechanisms. Through the detailed DFT calculations, insights into the mechanisms are obtained, and the substituent effects and the role of the bases are understood.

A comprehensive density functional theory study has been performed on the mechanism of Cp*Rh(III)- catalyzed C–H activation of N-(pivaloyloxy)acrylamide with alkynyl triazene. The calculated results reveal that a concerted Lossen rearrangement/OPiv migration from N to Rh is the most favorable pathway to afford an isocyanate intermediate, where a redox-neutral process is involved without the involvement of a Rh(V)-nitrenoid species. Subsequently, the annulation of a rearranged six-membered ring intermediate is realized through a nucleophilic attack of Rh-bonded carbon on the isocyanate carbon, and this process is likely to be the rate-determining step for the entire catalytic cycle, with an overall energy barrier of 20.5 kcal mol1. In addition, the stepwise OPiv migration from N to Rh and C–N reductive elimination, and vice versa, are competitive to yield a non-rearranged byproduct, which experiences a Rh(III)–Rh(V)–Rh(III) transformation of oxidation state.

Transition-metal-catalyzed decarboxylative and C–H functionalization strategy for the construction of Csp2-Csp2, Csp2-Csp, and Csp2-Csp3 bonds has been extensively studied. However, research surveys of this synthetic strategy for the Csp3-Csp3 bond forming reactions are surprisingly scarce. Herein, we present an efficient approach for the rapid formation of Csp3–Csp3 bond through copper-catalyzed decarboxylative Csp3–H functionalization. The present method should provide a useful access to C3-substituted indole scaffolds with possible biological activities. Mechanistic experiments and DFT calculations supported a dual-Cu(II)-catalytic cycle involving rate-determining decarboxylation in an outer-sphere radical pathway and spin-crossover-promoted C–C bond formation. This strategy offers a promising synthesis method for the construction of Csp3–Csp3 bond in the field of synthetic and pharmaceutical chemistry and extends the number of still limited copper-catalyzed decarboxylative Csp3–Csp

A tris(4-methoxyphenyl)amine (TMPA)-catalyzed paired-electrolysis sulfonylation is reported. TMPA first serves as the electron donor, thereby facilitating the reduction of sulfonyl chloride; subsequently, the resulting TMPA•+ oxidizes the benzyl radical intermediate. TMPA and the chloride anion also act as a Brønsted base to promote deprotonation at the α-carbon of the sulfonyl group. The current results elucidate a novel paradigm of triarylamine multiple activation, which may stimulate continuous exploration of multiple action modes of other mediators.

Cu-catalyzed aerobic epoxidation offers cost-effective access to epoxides, a class of versatile chemical building blocks. Herein, a computational mechanistic study was performed to investigate Cu-catalyzed aerobic epoxidation of tertiary allylic alcohols and ethers. In contrast to the previously proposed solvent−O2 cascade activation and the O2-activation mechanisms, a substrate− O2−solvent cascade activation mechanism was revealed for not only high-strained substrates but also low- and nonstrained substrates tested herein. Specifically, it involves an induction period for the in situ generation of the actual catalyst, a Cu(II)- alkylperoxide complex derived from solvent 1,4-dioxane. Three substrate-activation pathways, depending on the substrate strain and the presence or absence of an allylic hydroxyl group, were found to be operative in this period. For the actual catalytic epoxidation, the mononuclear Cu(II) pathway was found to be favored over the dinuclear Cu(III)-oxo pathway and

1,4-Dicarbonyl motifs are notoriously difficult to synthesize, yet the mechanistic underpinnings of conventional electron donor– acceptor (EDA) strategies remain contentious. Here, we unambiguously resolve this debate and disprove the hydrogenbonding EDA (H-EDA) mechanism for decarboxylative acylation of activated alkenes with α-keto acids, establishing a concerted proton-coupled electron transfer (PCET) pathway as the exclusive operative mechanism. A combination of spectroscopic, electrochemical, photophysical, and computational studies provides definitive evidence against EDA/H-EDA formation and electron transfer, while DFT calculations revealed an exceptionally low activation barrier for concerted PCET (ΔG‡/ΔE‡ = 5.1–11.6 kcal mol-1), consistent with high efficiency under mild conditions. This photocatalyst- and base-free visible-light protocol enables rapid assembly of diverse 1,4-dicarbonyl compounds, with broad substrate scope, exceptional functional group compatibility, and reli

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 tris(4-methoxyphenyl)amine (TMPA)-catalyzed paired-electrolysis sulfonylation is reported. TMPA first serves as the electron donor, thereby facilitating the reduction of sulfonyl chloride; subsequently, the resulting TMPA•+ oxidizes the benzyl radical intermediate. TMPA and the chloride anion also act as a Brønsted base to promote deprotonation at the α-carbon of the sulfonyl group. The current results elucidate a novel paradigm of triarylamine multiple activation, which may stimulate continuous exploration of multiple action modes of other mediators.

Cu-catalyzed aerobic epoxidation offers cost-effective access to epoxides, a class of versatile chemical building blocks. Herein, a computational mechanistic study was performed to investigate Cu-catalyzed aerobic epoxidation of tertiary allylic alcohols and ethers. In contrast to the previously proposed solvent−O2 cascade activation and the O2-activation mechanisms, a substrate− O2−solvent cascade activation mechanism was revealed for not only high-strained substrates but also low- and nonstrained substrates tested herein. Specifically, it involves an induction period for the in situ generation of the actual catalyst, a Cu(II)- alkylperoxide complex derived from solvent 1,4-dioxane. Three substrate-activation pathways, depending on the substrate strain and the presence or absence of an allylic hydroxyl group, were found to be operative in this period. For the actual catalytic epoxidation, the mononuclear Cu(II) pathway was found to be favored over the dinuclear Cu(III)-oxo pathway and

1,4-Dicarbonyl motifs are notoriously difficult to synthesize, yet the mechanistic underpinnings of conventional electron donor– acceptor (EDA) strategies remain contentious. Here, we unambiguously resolve this debate and disprove the hydrogenbonding EDA (H-EDA) mechanism for decarboxylative acylation of activated alkenes with α-keto acids, establishing a concerted proton-coupled electron transfer (PCET) pathway as the exclusive operative mechanism. A combination of spectroscopic, electrochemical, photophysical, and computational studies provides definitive evidence against EDA/H-EDA formation and electron transfer, while DFT calculations revealed an exceptionally low activation barrier for concerted PCET (ΔG‡/ΔE‡ = 5.1–11.6 kcal mol-1), consistent with high efficiency under mild conditions. This photocatalyst- and base-free visible-light protocol enables rapid assembly of diverse 1,4-dicarbonyl compounds, with broad substrate scope, exceptional functional group compatibility, and reli

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.