Development of a New Herbicide, Oxaziclomefone

「INTRODUCTION」 A novel oxazinone class herbicide, oxaziclomefone is a pre- and post-emergence paddy rice herbicide and pre-emergence turf herbicide. It controls barnyardgrass, sedges and certain broad-leaved weeds in paddy rice and annual grass in turf at low rates. It was discovered by the former Mitsubishi Petrochemical Co., Ltd. (Bayer CropScience K.K.) and subsequently developed in collaboration with the National Federation of Agricultural Co-operative Associations (ZEN-NOH). The herbicide was first registered in Japan in 2000 under the trade name of Fullhouse(R) for use on turf and also approved in combination with sulfonylurea herbicides for paddy rice as Homerue(R), THOROUGHBRED(R), Pat-Ful(R), Sat-Ful(R), and Tredy(R). Registration occurred for another combination product mixed with pyrazole class herbicide and sedge herbicide as Samurai(R). This paper briefly describes the history of discovery, synthesis, herbicidal characteristics and safety of oxaziclomefone. DISCOVERY and SYNTHESIS Through a prototype lead compound, 3-(1-phenyl-1-methylethyl)-2,3-dihydro-6-methyl-5-phenyl-2H-1,3-oxazin-4-one, many oxazinone derivatives were synthesized and their herbicidal activity and crop safety were evaluated. As a result of precise investigations, 3-[1-(3,5-dichlorophenyl)-1-methylethyl]-2,3-dihydro-6-methyl-5-phenyl-2H-1,3-oxazin-4-one (oxaziclomefone; MY-100) was selected as the most potent candidate active against barnyardgrass.