Indazole-containing derivatives represent one of the most important heterocycles in drug molecules. Diversely substituted indazole derivatives bear a variety of functional groups and display versatile biological activities; hence, they have gained considerable attention in the field of medicinal chemistry. This review aims to summarize the recent advances in various methods for the synthesis of indazole derivatives. The current developments in the biological activities of indazole-based compounds are also presented.

Coumarin compounds have a variety of biological activities such as anti-tumor, anti-coagulation, anti-HIV, anti-fungal, and insecticidal. Amide and sulfonamide compounds have been used as fungicides for half a century, and dozens of varieties have been developed so far. This study focused on the introduction of carboxamide and sulfonamide moieties in a coumarin core to discover novel derivatives. Based on this strategy, we synthesized two series of novel carboxamide and sulfonamide substituted coumarin derivatives, and their fungicidal activity was also investigated. Some designed compounds possessed potential activities against six phytopathogenic fungi in the primary assays, highlighted by compound 6r. Compound 6r exhibited stronger fungicidal activity against Botrytis cinerea (EC₅₀ = 20.52 µg/mL) and will be the lead structure for further study.

Procymidone is a widely used fungicide in the prevention and treatment of fungal diseases on many crops in China. Part of the procymidone will enter the soil during the application process. Procymidone may exhibit environmental behavior diversity in different soils. Therefore, it is extremely important to clarify the environmental behavior of procymidone in soil for its environmental safety evaluation. Here, the degradation, adsorption, and mobility behaviors of procymidone in four typical types of Chinese soil were investigated for the first time. The half-lives of procymidone in the soils ranged from 14.3 d to 24.1 d. The degradation rates of procymidone in the soils were promoted by organic matter content, moisture content, and microorganisms. Furthermore, the degradation of procymidone on the soil surface was promoted by light. The desorption rates of procymidone in laterite soil, yellow brown soil, black soil, and chestnut soil were 27.52 ± 0.85%, 16.22 ± 0.78%, 13.67 ± 1.29%, and 7.62 ± 0.06%, respectively, which were contrary to the adsorption ability. The mobility order of procymidone in the soils was: laterite soil > yellow brown soil > black soil > chestnut soil, with the R_f values of 0.28, 0.22, 0.18, and 0.16, respectively. Three degradation products of procymidone were identified by liquid chromatography coupled with quadrupole/time-of-flight mass spectrometry, and the degradation pathway of procymidone in the soil was speculated. The results will provide a theoretical basis for the removal of procymidone in the soil environment.

A series of fluorinated 7-hydroxycoumarin derivatives containing an oxime ether moiety have been designed, synthesized and evaluated for their antifungal activity. All the target compounds were determined by ¹H-NMR, ¹³C-NMR, FTIR and HR-MS spectra. The single-crystal structures of compounds 4e, 4h, 5h and 6c were further confirmed using X-ray diffraction. The antifungal activities against Botrytis cinerea (B. cinerea), Alternariasolani (A. solani), Gibberella zeae (G. zeae), Rhizoctorzia solani (R. solani), Colletotrichum orbiculare (C. orbiculare) and Alternaria alternata (A. alternata) were evaluated in vitro. The preliminary bioassays showed that some of the designed compounds displayed the promising antifungal activities against the above tested fungi. Strikingly, the target compounds 5f and 6h exhibited outstanding antifungal activity against B. cinerea at 100 μg/mL, with the corresponding inhibition rates reached 90.1 and 85.0%, which were better than the positive control Osthole (83.6%) and Azoxystrobin (46.5%). The compound 5f was identified as the promising fungicide candidate against B. cinerea with the EC₅₀ values of 5.75 μg/mL, which was obviously better than Osthole (33.20 μg/mL) and Azoxystrobin (64.95 μg/mL). Meanwhile, the compound 5f showed remarkable antifungal activities against R. solani with the EC₅₀ values of 28.96 μg/mL, which was better than Osthole (67.18 μg/mL) and equivalent to Azoxystrobin (21.34 μg/mL). The results provide a significant foundation for the search of novel fluorinated 7-hydroxycoumarin derivatives with good antifungal activity.

Iron (III) triflate was used as an efficient catalyst for N- t-butoxycarbonylation of amines with di- t-butyl dicarbonate under solvent-free conditions at room temperature. Various aliphatic, aromatic, heterocyclic amines and aminols were protected as their corresponding mono-carbamates in excellent yields and short reaction times. Only two of the 23 monocarbamates were new. No competitive side reactions such as isocyanate, urea, nor N,N-di-Boc formation were observed. The reported method is mild and has the advantages of low cost, chemoselectivity and, because no solvent is used and the catalyst can be recycled, it is classifiable as a green procedure.