Benzoxazoles as novel herbicidal agents

• Published in: Pest management science 2019-01, Vol.75 (1), p.262-269
• Main Authors: Sangi, Diego P, Meira, Yuri G, Moreira, Natália M, Lopes, Thais A, Leite, Mathias P, Pereira‐Flores, Milton E, Alvarenga, Elson S
• Format: Article
• Language: English
• Subjects: benzoxazoles; Benzoxazoles - pharmacology; Biological activity; cucumber; Cucumis sativus - drug effects; Germination; herbicide; Herbicide resistance; Herbicides; Herbicides - pharmacology; Lycopersicon esculentum - drug effects; onion; Onions - drug effects; Organic chemistry; Oxazole; Oxazolidine; Phytotoxicity; Seed germination; Sorghum; Sorghum - drug effects; Structure-Activity Relationship; Substitution reactions; synthesis; tomato; Tomatoes
• ISSN: 1526-498X; 1526-4998
• DOI: 10.1002/ps.5111

BACKGROUND Despite the need to develop new herbicides with different modes of action, due to weed resistance, many important classes of compounds have been studied poorly for this purpose. Benzoxazoles are considered privileged structures because of their biological activities, but their phytotoxic activities have not received a lot of attention until now. RESULTS Double vinylic substitution reactions were carried out to furnish four 2‐nitromethylbenzoxazoles and one oxazolidine. Benzoxazol‐2‐ylmethanamine was obtained by reduction of compound 3a. These compounds were evaluated for their phytotoxicity in Allium cepa (onion), Solanum lycopersicum (tomato), Cucumis sativus (cucumber) and Sorghum bicolor (sorghum). Comparison with oxazolidine analogue allowed us to understand that the benzoxazolic structure is very important for the herbicidal activity. CONCLUSION All the synthesized compounds exhibited biological activity on seed germination. The four 2‐nitromethylbenzoxazoles showed phytotoxic activity and the 5‐chloro‐2‐(nitromethyl)benzo[d]oxazole (3b) exhibited higher inhibition than the commercial herbicide against all four plant species tested. © 2018 Society of Chemical Industry This article presents the synthesis and phytotoxic evaluation of benzoxazole derivatives. Two compounds are significantly better than S‐metolachlor (Dual) on three species tested.