An efficient synthesis of highly functionalized chiral β-amino ester derivatives containing benzothiophene and benzothiazole moieties is developed by a Mannich-type reaction using a cinchona alkaloid-derived thiourea catalyst. The desired products were obtained in good yields and high enantioselectivities (~86% yield, >99% ee) using to the optimized reaction conditions. The synthesized compounds were characterized by ¹H-NMR, ¹³C-NMR, IR, and HREI-MS analyses. The bioassays identified that compound 5dr has excellent antifungal activity, with a 60.53% inhibition rate against F. oxysporum, higher than that of the commercial agricultural fungicide hymexazol, whose inhibition rate was 56.12%.

Fifteen novel carbazole derivatives of 2-(9H-carbazol-9-yl)-N-(5-phenyl-1,3,4-thiadiazol-2-yl)acetamide were designed, synthesized and evaluated for their antifungal activities against Pellicularia sasakii (P. sasakii), Fusarium oxysporum (F. oxysporum), Gibberella zeae (G. zeae), Phytophthora infestans (P. infestans), Cytospora mandshurica (C. mandshurica) and Capsicum wilt (C. wilt). The results of antifungal activity tests indicated that the inhibitory rates of compounds 2-(2-chloro-9H-carbazol-9-yl)-N-(5-(4-fluorophenyl)-1,3,4-thiadiazol-2-yl)acetamide (3h) and 2-(2-chloro-9H-carbazol-9-yl)-N-(5-(thiophen-2-yl)-1,3,4-thiadiazol-2-yl)acetamide (3o) against P. sasakii were 72.89% and 74.29%, respectively, which displayed better bioactivity compared with commercial fungicides hymexazol (53.09%) and carbendazim (69.65%). Meanwhile, compounds 2-(9H-carbazol-9-yl)-N-(5-(thiophen-2-yl)-1,3,4-thiadiazol-2-yl)acetamide (3f) and 2-(3-iodo-9H-carbazol-9-yl)-N-(5-(p-tolyl)-1,3,4-thiadiazol-2-yl)acetamide (3 l) exhibited the inhibition rates of 72.40% and 67.65% against C. wilt, respectively, which were better than the commercial fungicides hymexazol (50.21%) and carbendazim (65.33%). Graphical Abstract

Starting from benzofuran-2-methanal, 6-substituted benzothiazole-2-amines and malonic esters, sixteen title compounds were designed and synthesized seeking to introduce anti-TMV activity. The structures of the newly synthesized compounds were confirmed by ¹H-NMR, ¹³C-NMR, IR spectra, and MS (HREI) analysis. The bioassays identified some of these new compounds as having moderate to good anti-TMV activity. The compounds 5i and 5m have good antiviral activity against TMV with a curative rate of 52.23% and 54.41%, respectively, at a concentration of 0.5 mg/mL.

A series of 1,4-benzoxazin-3-one derivatives containing an acylhydrazone moiety were designed, synthesized and evaluated for their in vitro antifungal activities against Gibberella zeae, Pellicularia sasakii, Phytophthora infestans, Capsicum wilt, and Phytophthora capsica. The structures of target compounds were characterized by ¹H NMR, ¹³H NMR, ¹⁹F NMR and HRMS. The preliminary antifungal evaluation of all target compounds showed that some target compounds possessed moderate to good activities against G. zeae, P. sasakii, P. infestans and C. wilt. Among them, compounds 5L and 5o exhibited noticeable inhibition effects against G. zeae with the EC₅₀ values (effective concentration for 50% activity) of 20.06 and 23.17 μg/ml, respectively, which were even nearly double effective than that of hymexazol (40.51 μg/ml). Meanwhile, compound 5q displayed a notable inhibitory effect toward P. sasakii, with the EC₅₀ value of 26.66 μg/ml, which was better than that of hymexazol (32.77 μg/ml). In addition, compound 5r yielded the EC₅₀ value of 15.37 μg/ml against P. infestans, which was less than those of hymexazol (18.35 μg/ml) and carbendazim (34.41 μg/ml). Eventually, compound 5p showed higher inhibitory effect against C. wilt, with EC₅₀ value of 26.76 μg/ml, which was better than that of hymexazol (>50 μg/ml).

A novel class of eighteen 2-((9H-carbazol-9-yl)methyl)-5-(benzylthio)-1,3,4-oxadiazole derivatives were designed, synthesized and screened for their in vitro antibacterial activities against Pseudomonas syringae pv. Actinidiae (Psa), Xanthomonas oryzae pv. Oryzae (Xoo) and Xanthomonas axonopodis pv. Citri (Xac). Preliminary bioactivity test results indicated that some compounds showed moderate to good inhibitory effects against the tested bacteria at the concentrations of 100 μg/mL and 50 μg/mL. Among them, compounds 2-((9H-carbazol-9-yl)methyl)-5-((2,6-dichloro benzyl) thio)-1,3,4-oxadiazole (5e) and 2-((9H-carbazol-9-yl)methyl)-5-((4-(trifluoromethyl)benzyl)thio)- 1,3,4-oxadiazole (5m) exhibited the best inhibitory effects against Psa, Xoo and Xac than other compounds, which displayed a wide range of antibacterial activities. Further bioactive applications of these molecules are in progress in our laboratories.