N-Azolyl Phenoxypyrimidine Herbicides: Novel Inhibitors of Carotenoid Biosynthesis Part 1

摘要

Substituted 2-azolyl-4-phenoxypyrimidines of formula 1 represent a new family of highly active herbicides that act by inhibiting carotenoid biosynthesis. Azole substituents on the pyrimidine are nitrogen-linked and include pyrazole, imidazole and triazole. These compounds are active preemergence and postemergence but tend to be more active preemergence. Selectivity was observed on wheat, corn, and soybeans. There was particular interest in these compounds as cereal herbicides for preemergent and early-postemergent weed control. High field efficacy was observed, particularly on broadleaf weeds. Pyrazolylpyrimidine 1a showed optimum activity in cereal field trials and gave excellent broadleaf weed control at rates as low at 5-10 g/ha, with good wheat safety. This paper will focus on chemistry, biology, structure-activity relationships, mode-of-action, and field activity for compounds of this herbicide class.