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Regioselective benzanilide bromination that generates either regioisomer from the same starting material is desirable. Herein, we develop switchable site-selective C(sp2)-H bromination by promoter regulation. This protocol leads to regiodivergent brominated benzanilide starting from the single substrate via selection of promoters. The protocol demonstrates excellent regioselectivity and good tolerance of functional groups with high yields. The utility effectiveness of this method has been well exemplified in the late-stage modification of biologically important molecules. [ABSTRACT FROM AUTHOR]

Rationale Methods Results Conclusions Electronically mismatched Diels–Alder reactions have gained much attention as an alternative pathway for C–C bond formation. To facilitate the development of facile organic transformations, mechanistic investigations are required. Spectroscopic methods (NMR, electron paramagnetic resonance and UV–visible) are normally adopted for mechanistic examinations, but further improvements in directly obtaining structural information of short‐lived intermediates are encouraged. Herein, an electronically mismatched Diels–Alder reaction between indole and 1,3‐cyclohexadiene was studied using in situ electrospray ionization mass spectrometry (in situ ESI‐MS). Based on direct sampling and detection of the in situ ESI‐MS without sample pretreatment, the structures and dynamics of important intermediates were examined on‐line.A syringe‐based photocatalytic reactor and in situ ambient MS (AMS) evaluation system was constructed for mechanism studies. The role of oxygen was confirmed via control reaction employed in the N2‐bubbled system. The stepwise cation radical‐based pathway and the [2 + 2] cycloaddition process were determined through a series of experiments, including solvent evaluation, MS/MS experiments and dynamic monitoring.The dependence of the reaction on solvent polarity demonstrated that the reaction occurs via the formation of cation radicals, which were captured, identified and dynamically monitored via in situ ESI‐MS. Without pre‐separation, the intermediate of [2 + 2] cycloaddition was identified and the cycloaddition process was thereby determined to be the combination of [4 + 2] cycloaddition and [2 + 2] cycloaddition. In addition, oxygen was proved to act as an electron mediator for both catalyst Ru(bpz)3(PF6)2 and radical cations.The mechanism of an electronically mismatched Diels–Alder reaction was successfully deduced by in situ MS associated with a syringe‐based photocatalytic reactor. The structures and dynamics of cation radicals, the effect of O2 for the reaction and the detailed process of [2 + 2] cycloaddition have been well demonstrated. This work could not only promote the understanding and development of facile photocatalytic transformations, but also enlarge the application range of AMS in on‐line monitoring. [ABSTRACT FROM AUTHOR]

Chemical reactions conducted in different media (liquid phase, gas phase, or surface) drive developments of versatile techniques for the detection of intermediates and prediction of reasonable reaction pathways. Without sample pretreatment, ambient mass spectrometry (AMS) has been applied to obtain structural information of reactive molecules that differ in polarity and molecular weight. Commercial ion sources (e.g., electrospray ionization, atmospheric pressure chemical ionization, and direct analysis in real‐time) have been reported to monitor substrates and products by offline reaction examination. While the interception or characterization of reactive intermediates with short lifetime are still limited by the offline modes. Notably, online ionization technologies, with high tolerance to salt, buffer, and pH, can achieve direct sampling and ionization of on‐going reactions conducted in different media (e.g., liquid phase, gas phase, or surface). Therefore, short‐lived intermediates could be captured at unprecedented timescales, and the reaction dynamics could be studied for mechanism examinations without sample pretreatments. In this review, via various AMS methods, chemical reaction monitoring and mechanism elucidation for different classifications of reactions have been reviewed. The developments and advances of common ionization methods for offline reaction monitoring will also be highlighted. [ABSTRACT FROM AUTHOR]

By simple microwave irradiation, a high-throughput, single-step, rapid but controllable synthesis of stable colloidal CsPbX3 perovskite NCs with tunable properties and morphologies (nanocubes, nanorods, nanowires, quadrate nanoplates and hexagonal nanoplates) was achieved. It was employed in a heterogeneous solid–liquid reaction system within minutes without any tedious pre-preparation. [ABSTRACT FROM AUTHOR]

Changes in chemical composition during food processing and handling are crucial for the alteration of food flavor and function, and accurate characterization of key chemical reaction pathways in complex food matrices is one of the core challenges in food chemistry research. Here, this study attempts to establish a strategy for sensitive characterization of chemical reactions during food processing based on on-line extraction electrospray ionization mass spectrometry (oEESI-MS). The process of making garlic into black garlic, a traditional global flavor food, was chosen as an exemplary research template. The direct MS characterization of raw garlic as well as black garlic samples with different processing times was achieved by using the self-constructed oEESI-MS device. Benefiting from the high tolerance of oEESI-MS to complex matrix interferences, all samples can be fingerprinted directly without any pre-processing or pre-separation. As a result, oEESI-MS achieved a sensitive characterization of the changes of key substances during the preparation of black garlic. Further, a new chemical reaction pathway, the degradation of γ-L-glutamyl-S-allyl-L-cysteine to S-allyl-l-cysteine, was completely demonstrated by analyzing the differential substances before and after the treatment, and verified by standard substances and chemical theory calculations. In conclusion, a complete oEESI-MS-based strategy for tracking the substance changes in food processing was established in this study, which has a widely applicable prospect for the precise setting of food processing time and parameters, and the innovation of processing technology., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2025 Elsevier Ltd. All rights reserved.)