Reactions of thiocarboxylic acids and dithiocarbamate-terminal amines provide a linker-traceless method for amide bond formation under mild conditions, whereas the reaction mechanism is not clear. A systematic study was performed herein with density functional theory (DFT) calculations to elucidate the detailed mechanism, the substitution effect on the proposed CS2-releasing 1,3-acyl transfer and the differences between CS2- and CO2-releasing 1,3-acyl transfer. Relevant results indicate that this type of reaction proceeds via the nucleophilic addition of an in situ generated dithiocarbamic acid on thiocarboxylic acid, H2S elimination, rate-determining 1,3-acyl transfer and CS2 release. For the generation of secondary amides via the 1,3-acyl transfer, a thiocarboxylic acid- or dithiocarbamic acid-assisted pathway, in which both the carbonyl group and amide nitrogen are activated, is the most favored. For the generation of tertiary amides, MeOH-assisted carbonyl-activation is the most fa

Pd-catalyzed C(sp3)−H activation/alkylation of 2-tert-butylaryl halides with alkyl halides and CH2Br2 represents an advantageous strategy for the C−H functionalization with halogens as traceless directing groups. Several possible mechanisms were proposed for the reactions, but no further evidence was available to judge their relative feasibilities. Herein, a mechanistic study was performed with the aid of density functional theory (DFT) methods. Calculations indicate that the coupling of aryl bromides with alkyl chlorides is likely to generate alkylated benzocyclobutenes via aryl−Br oxidative addition on Pd(0) catalysts, C(sp3)−H activation, alkyl−Cl oxidative addition, aryl−alkyl reductive elimination, aryl−H activation, and aryl−C(sp3) reductive elimination. The coupling of aryl iodides with CH2Br2 is likely to generate indane derivatives via aryl−I oxidative addition, C(sp3)−H activation, alkyl−Br oxidative addition, aryl−CH2Br reductive elimination, alkyl−Br oxidative addition, C(s

A novel boron ester-catalyzed amidation reaction of carboxylic acids and amines with unprecedented functional group tolerance was recently reported. To gain deeper insights into this reaction, a computational study with density functional theory methods was performed in this manuscript. Calculations indicate that the amidation starts with the condensation of carboxylic acids with the boron ester catalyst. The resulting monoacyloxylated boron species further undergoes the carboxylic acid-assisted nucleophilic addition with amines to generate the amide product and a monohydroxyboron species. The condensation of the carboxylic acid with the monohydroxyboron species with the assistance of an amine regenerates monoacyloxylated boron species to finish the catalytic cycle. The rate-determining step is catalyst regeneration and the amine-coordinated monohydroxyboron species is the resting state in the catalytic cycle. The present results are consistent with the previous NMR study and the obser

Iridium complexes have been widely applied to energy and chemical industry, pharmaceutical industry, and organic synthesis. As a parameter reflecting the interaction between ligands and metal centers, trans-effect plays an important role in the kinetics/thermodynamic stability, the reactivity and the catalytic performance of transition metal complexes. A systematic study was conducted herein to address the abnormal trans-effect of iridium halide complexes reported by Werneke et al. It is found that the observed unconventional trans-effect mainly results from the different cis-to-trans isomerization energies of different tetra-coordinated iridium complexes. The relevant results provide deeper insights into understanding the trans-effect based on the experimentally measured bond dissociation energies, and thus benefit the design and development of new, highly effective hydrogen fuel carrier metal complexes.

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.