Compounds of the formula ##STR1## wherein R, R.sub.1, R.sub.2 and R.sub.3 are substituents of diverse types, and salts thereof. The compounds as well as their salts are useful as herbicides.
式为##STR1##的化合物,其中R、R.sub.1、R.sub.2和R.sub.3是不同类型的取代基,以及它们的盐。这些化合物及其盐可用作
除草剂。