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An oxidative strategy is reported to access α-oxo BMIDA gold carbenes directly from BMIDA-terminated alkynes. Besides offering expedient access to seldom studied boryl metal carbenes, these BMIDA gold carbene species undergo facile insertions into methyl, methylene, methine, and benzylic C-H bonds in the absence of the Thorpe-Ingold effect. They also undergo efficient OH insertion, cyclopropanation, and F-C alkylations. This chemistry provides rapid access to structurally diverse α-BMIDA ketones, which are scarcely documented. In combination with DFT studies, the role of BMIDA is established to be an electron-donating group that attenuates the high electrophilicity of the gold carbene center.

The mono-base-stabilized 1,2-diboranylidenehydrazine derivatives featuring a 1,3-dipolar BNN skeleton are obtained by dehydrobromination of [ArB(Br)NH]2 (Ar = 2,6-diphenylphenyl (Dpp), Ar = 2,6-bis(2,4,6-trimethylphenyl)phenyl (Dmp) or Ar = 2,4,6-tri-tert-butylphenyl (Mes*)) with N-heterocyclic carbenes (NHCs). Depending on the Ar substituents, such species can be isolated as a crystalline solid (Ar = Mes*) or generated as reactive intermediates undergoing spontaneous intramolecular aminoboration of the proximal arene rings via [3 + 2] cycloaddition (Ar = Dpp or Dmp). The latter reactions showcase the 1,3-dipolar reactivity toward unactivated arenes at ambient temperature. In addition, double cycloaddition of the isolable BNN species with two CO2 molecules affords a bicyclic species consisting of two fused five-membered BN2CO rings. The electronic structures of these BNN species and the mechanisms of these cascade reactions are interrogated through density functional theory (DFT) calculations.

Dehydrogenative coupling (DC) and borrowing hydrogen(ation) (BH) reactions are crucial in modern organic synthesis, offering efficient and sustainable ways to create valuable compounds. However, they often face a significant challenge: the alkoxide trap. This Concept explores the alkoxide trap in DC and BH reactions, starting with the basic mechanisms and the role of alkoxide intermediates. It then examines how the alkoxide trap leads to catalyst deactivation and reduced selectivity, influenced by thermodynamic and kinetic factors. To address this, we review recent advances in catalyst design, ligand engineering, and optimized reaction conditions, along with the use of in‐situ spectroscopy and computational modelling, to better understand the underlying processes and guide rational catalyst development. Furthermore, this Concept highlights the broad applicability of DC, and BH reactions across various substrates, underscoring the urgency of addressing the alkoxide trap issue to unlock their full synthetic potential. [ABSTRACT FROM AUTHOR]

The Guerbet reaction is important for the synthesis of longer‐chain monoalcohols like isobutanol through catalytic transfer hydrogenation from short‐chain methanol and ethanol. However, the mechanism becomes complicated, especially considering the variations in the different metal‐ligand cooperation (MLC) catalysts used. In order to further understand the Guerbet reaction, DFT studies were performed to figure out the detailed mechanism initiated by the unique Mn‐PCP MLC Catalyst. Our results suggest that even with the assistance of the carbanion site of the PCP ligand, the direct substitution mechanism is less favored than the condensation‐reduction mechanism. The key step of the reaction is the final reduction of the carbonyl, in which the 1,4‐reduction of the unsaturated aldehyde is prior to the 3,4‐reduction or 1,2‐reduction due to the stronger interaction between the catalyst and the substrate. It is found that the production of isobutanol is preferred over n‐butanol because of the lower total free energy barrier and lower relative free energy of the product. Finally, by changing the electronic effect of the carbanion site of the catalyst, we found that the relation between the electronic effect and the highest free energy span was not monotonous and a point with optimal electronic effect exists numerically. [ABSTRACT FROM AUTHOR]

Gold allenylidene species have been seldom exploited as reactive intermediates in synthetically versatile catalytic reactions. By employing alkynylbenziodoxoles as the substrates and bifunctional WangPhos as the metal ligand, this work demonstrated ready catalytic access to these intermediates of general substitution patterns and their electrophilic reactivities at the γ‐carbon center with a diverse range of nucleophiles. The reaction is driven by the reductive decomposition of the benziodoxole moiety and achieves the replacement of a propargylic proton with an N/O/C‐based nucleophile, hence realizing reactivity umpolung. Corroborated by Density Functional Theory (DFT) calculations, the reaction mechanism involves a mild propargylic deprotonation. In contrast to prior works employing a tertiary amine functionality, a weakly BrØnsted‐basic amide group in WangPhos is surprisingly effective in deprotonation at the propargylic position under a gold‐ligand cooperation regime. [ABSTRACT FROM AUTHOR]

2D organic crystals play a unique role in photodetection owing to their tunable detection wavelength, low manufacturing cost, compatibility with lightweight, and controllable synthesis. However, their detection wavelength range mainly encompasses the visible (Vis) and near‐infrared (NIR) spectra. Herein, 2D erucamide crystals are synthesized using nitrogen gas and methanol as raw materials without catalysts at room temperature under atmospheric pressure via laser processing. The synthesized 2D erucamide is demonstrated to be a promising broad bandgap organic semiconductor material. A UV photodetector made of 2D erucamide exhibited a responsivity as high as 145 mA W−1, a millisecond‐level response speed, and an excellent detectivity of 4.96 × 109 Jones. Furthermore, the synthesized erucamide showed an excellent UV–vis suppression ratio (R254 nm/R532 nm) of 59. The synthesis mechanism of erucamide via laser bubbling in liquids is proposed. Thermodynamically, the high temperature of the bubbles is beneficial for nitrogen and methanol decomposition. Kinetically, rapid bubble quenching facilitates final product formation. This accomplishment represented the pioneering utilization of lasers in converting nitrogen gas into organic compounds while introducing 2D erucamide into the realm of organic UV photodetectors. [ABSTRACT FROM AUTHOR]

Mechanistic studies involving characterization of crucial intermediates are desirable for rational optimization of molecular catalysts toward CO2 reduction, while fundamental challenges are associated with such studies. Herein we present the systematic mechanistic investigations on a pyrene‐appended CoII macrocyclic catalyst in comparison with its pyrene‐free prototype. The comparative results also verify the reasons of the higher catalytic activity of the pyrene‐tethered catalyst in noble‐metal‐free CO2 photoreduction with various photosensitizers, where a remarkable apparent quantum yield of 36±3 % at 425 nm can be obtained for selective CO production. Electrochemical and spectroelectrochemical studies in conjunction with DFT calculations between the two catalysts have characterized the key CO‐bound intermediates and revealed their different CO‐binding behavior, demonstrating that the pyrene group endows the corresponding CoII catalyst a lower catalytic potential, a higher stability, and a greater ease in CO release, all of which contribute to its better performance. [ABSTRACT FROM AUTHOR]

We disclose the development of the Rh-catalyzed amine-directed remote 5,6-carboamination protocol of pyridines via dual Csp2–H functionalizations. A variety of readily available 2-aminopyridines and 1,2,3-triazoles are allowed for coupling cyclization to access polyfunctionalized azaindoles. Mechanistic studies including DFT calculations unveil that relay carbenoid-electrophilic addition to pyridines and the sequential pyridyl Csp2–H amination are involved in this transformation. The post-synthetic utility of this methodology is showcased by versatile and site-selective modification of azaindoles. [ABSTRACT FROM AUTHOR]