Abstract: This invention provides 1,3-oxazin-4-one derivatives represented by following general formula (I): ##STR1## in which R.sup.1 represents a phenyl group which may be substituted; R.sup.2 represents a hydrogen atom or a lower alkyl group; R.sup.3 represents a hydrogen atom, a lower alkyl group, an aralkyl group or a phenyl group which may be substituted; R.sup.4 and R.sup.5 each independently represent a lower alkyl group; and W represents an oxygen atom or a group represented by the formula --N(R.sup.6)-- in which R.sup.6 represents a hydrogen atom, a lower alkyl group, a lower alkenyl group or a lower alkynyl group. There are also provided herbicidal compositions containing the derivatives and intermediates for preparing them. The compounds according to the present invention exhibit strong herbicidal activities and thus they are useful as active ingredients of agricultural chemicals.

Abstract: A compounds represented by the formula ##STR1## wherein X represents a fluorine atom,W represents an oxygen atom, sulfur atom or group --OCH.sub.2 --,Z.sup.1 and Z .sup.2 each represent a nitrogen atom or group CH, but when Z.sup.1 is a nitrogen atom, Z.sup.2 represents a nitrogen atom or group CH and when Z.sup.1 is a group CH, Z.sup.2 represents a nitrogen atom,R.sup.1 and R.sup.2 each independently represent either a hydrogen atom, halogen atom or mono- or dilower alkyl-substituted amino, or a lower alkyl, lower alkoxy or lower alkylthio each of which may be substituted with a halogen atom,R.sup.3 and R.sup.4 form together with the carbon atoms to which they bind respectively a 5- to 8-membered carbon ring.