New 2-phenyl-4,5,6,7-tetrahydro-2H-indazole derivatives as paddy field herbicides

摘要

A series of 3-chloro-2-(4-chloro-2-fluorophenyl)-4,5,6,7-tetrahydro-2H-indazole derivatives containing various substituted isoxazolinylmethoxy groups at the 5-position of the benzene ring were synthesized and their herbicidal activities assessed under greenhouse and flooded paddy conditions.Among them,compounds having a phenyl or cyano substituent at the 3-position of the 5-methyl-isoxazolin-S-yl structure demonstrated good rice selectivity and potent herbicidal activity against annual weeds at 16-63 gAI ha~(-1) under greenhouse conditions.Field trials indicated that these two compounds controlled a wide range of annual weeds rapidly with a good tolerance on transplanted rice seedlings by pre-emergence application.They showed a low mammalian and environmental toxicity in various toxicological tests.