| abstract |
New 3-phenyl-5-substituted-4(1H)pyridones of the formula I <IMAGE> and salts thereof are prepared by cyclising a compound of the formula IV <IMAGE> in which one of the substituents Q<1> and Q<2> represents the group =CH-OH and the other of the two substituents Q<1> and Q<2> represents the group =CH-N(R<9>)2 with a compound of the formula RNH2 or with acid addition salts thereof. However, those compounds of the formula I in which R is an acetoxy group are prepared by cyclising the compounds of the formula IV with hydroxylamine or its acid addition salt and then acetylating the resulting compounds where R has the meaning of a hydroxyl group. Reacting them with phosphorus pentasulphide, the pyridones of the formula I are converted into the corresponding pyridothiones. In the compounds of the formulae I and IV, the substituents have the meaning given in Patent Claim 1. The new 3-phenyl-5-substituted-4(1H)pyridones, the corresponding pyridothiones, and also their salts, possess a herbicidal activity against a very wide spectrum of weeds, and they are therefore used as the active component in herbicides. |