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Myrosinase (Myr), as a unique β-thioglucosidase enzyme capable of converting natural and gut bacterial metabolite glucosinolates into bioactive agents, has recently attracted a great deal of attention because of its essential functions in exerting homeostasis dynamics and promoting human health. Such nutraceutical and biomedical significance demands unique and reliable strategies for specific identification of Myr enzymes of gut bacterial origin in living systems, whereas the dearth of methods for bacterial Myr detection and visualization remains a challenging concern. Herein, we present a series of unique molecular probes for specific identification and imaging of Myr-expressing gut bacterial strains. Typically, an artificial glucosinolate with an azide group in aglycone was synthesized and sequentially linked with the probe moieties of versatile channels through simple click conjugation. Upon gut bacterial enzymatic cleavage, the as-prepared probe molecules could be converted into reactive isothiocyanate forms, which can further act as reactive electrophiles for the covalent labeling of gut bacteria, thus realizing their localized fluorescent imaging within a wide range of wavelength channels in live bacterial strains and animal models. Overall, our proposed method presents a novel technology for selective gut bacterial Myr enzyme labeling in vitro and in vivo . We envision that such a rational probe design would serve as a promising solution for chemoprevention assessment, microflora metabolic mechanistic study, and gut bacterium-mediated physiopathological exploration.

A metal-free method for the construction of 2-substituted quinolines and benzo[ f ]quinolines from aromatic amines, aldehydes, and tertiary amines has been demonstrated. Cheap and readily available tertiary amines acted as the vinyl source. A new pyridine ring was selectively formed via [4 + 2] condensation that was promoted by ammonium salt under neutral conditions and an oxygen atmosphere. This strategy provided a new route for the preparation of various quinoline derivatives with different substituents at the pyridine ring, which provides the possibility of further modification.

A CuBr 2 -catalyzed annulation of 2-bromo- N -arylbenzimidamide with selenium/sulfur powder for the synthesis of benzo[ d ]isoselenazole and benzo[ d ]isothiazole in generally good yields was investigated. This synthetic strategy features good substrate scope and functional group tolerance. Furthermore, the corresponding products could be converted into N -aryl indoles via rhodium III -catalyzed ortho C-H activation of the N -phenyl ring, providing an efficient approach for axial aromatic molecules.

A novel strategy for the preparation of functional carbazoles through NaI-catalyzed formal [4 + 2] annulation of 2-(indol-3-yl)cyclohexanones and alkynes/alkenes has been developed. The present approach started from easily available raw materials and provided a variety of tetrahydrobenzo[ c ]carbazolones in satisfactory yields under metal- and solvent-free conditions. Furthermore, the products could be further transformed into structurally valuable carbazole-based conjugated derivatives.