CYCLIC AMIDE DERIVATIVE AND HERBICIDE CONTAINING THE SAME COMPOUND AS THE ACTIVE COMPONENT

PURPOSE:To obtain a new cyclic amide derivative exhibiting a herbicidal effect on various kinds of weeds in a remarkably small amount without damaging useful crops. CONSTITUTION:This compound is expressed by formula I [R is a lower alkyl, a lower alkenyl, a lower alkynyl, an aryl which may be substituted or an aralkyl which may be substituted; R is a five- to six-membered heterocyclic group which may be substituted (with H, a halogen, a lower alkyl, a lower alkoxy, a lower haloalkyl or a lower haloalkoxy) or fused with a benzene ring as necessary; R and R are each a lower alkyl; X 18 O or CH2l, e.g. 6-methyl-3-[ 1-methyl-1-(3-thienyl)ethyl]-5-phenyl-2,3-dihydro-4H-1, 3-oxazin-4-one. In the case of X:O, the compound of formula I can be synthesized by reacting a compound of formula II with a compound of formula III in a suitable solvent or without using a solvent at 90 to 160 deg.C. This compound has a high activity on annual and perennial weeds in a paddy field and broad leaf weeds, cyperaceous weeds and gramineous weeds in an upland field.