| abstract |
Compounds of the formulan and salts thereof, W and W, being independently 0 and S, A being a nitrogen-containing heterocyclic ring system, E being 0, S(O) m or NR 3 where m is 0-2, R 1 , R 2 and R 3 is hydrogen, C 1 -C 4 alkyl or C2-C4. alkenyl or alkynyl and E 1 being hydrogen, halogen or one of a variety of organic substituents. n The compounds are effective herbicides. |