Green Synthesis and Antifungal Activities of Novel <i>N</i>-Aryl Carbamate Derivatives

Abstract

Carbamate is a key structural motif in the development of fungicidal compounds, which is still promising and robust in the discovery of green pesticides. Herein, we report the synthesis and evaluation of the fungicidal activity of 35 carbamate derivatives, among which 19 compounds were synthesized in our previous report. These derivatives were synthesized from aromatic amides in a single step, which was a green oxidation process for Hofmann rearrangement using oxone, KCl and NaOH. Their chemical structures were characterized by 1H NMR, 13C NMR and high-resolution mass spectrometry. Their antifungal activity was tested against seven plant fungal pathogens. Many of the compounds exhibited good antifungal activity in vitro (inhibitory rate > 60% at 50 μg/mL). Compound 1ag exhibited excellent broad-spectrum antifungal activities with inhibition rates close to or higher than 70% at 50 μg/mL. Notably, compound 1af demonstrated the most potent inhibition against F. graminearum, with an EC50 value of 12.50 μg/mL, while compound 1z was the most promising candidate fungicide against F. oxysporum (EC50 = 16.65 μg/mL). The structure–activity relationships are also discussed in this paper. These results suggest that the N-aryl carbamate derivatives secured by our green protocol warrant further investigation as potential lead compounds for novel antifungal agents.

Keywords

• carbamate derivatives
• green synthesis
• phytopathogenic fungi
• antifungal activity
• structure–activity relationship