Turpentine‐Derived sec‐p‐Menthane‐1‐amine Derivatives: Synthesis, Herbicidal Activity, and 3D‐QSAR Study

Abstract

AbstractIn this study, a series of turpentine‐derived secondary amines (4 a–4 y) were synthesized and their structures were characterized by FTIR, 1HNMR, 13CNMR, and HRMS. The post‐emergence herbicidal activities against barnyard grass and rape were evaluated by the Petri dish method. The preliminary results showed that most of the amines exhibited higher herbicidal activities than that of glyphosate. Compound 4 n was the most potential compound whose IC50 values against root and shoot growth of barnyard grass were 1.75 mg L−1, and 9.33 mg L−1, against shoot growth of rape was 13.12 mg L−1, which were 6.9‐folds, 4.5‐folds, and 13.5‐folds, higher than that of glyphosate, respectively. In addition, compounds 4 e, 4 c, and 4 n were found to be selective to monocotyledons such as Lolium perenne, Setaria viridis, Digitaria sanguinalis and Echinochloa crus‐galli, and they were safe to wheat, sorghum, maize, and peanut at 100 mg L−1. Furthermore, a 3D‐QSAR model was built by the CoMFA method to study the relationship between herbicidal activities with structures, and its coefficient were r2=0.85, q2=0.58, indicating the 3D‐QSAR model was reasonable and predictable.