Herbidical compounds of the formula: <IMAGE> in which R1 denotes an optionally substituted hydrocarbon radical, R denotes the hydrogen atom or has one of the meanings given for R1; R2 and R3 denote the hydrogen atom or are such that OR2 and OR3 are hydrolyzable groups; R4 denotes a hydrogen atom or a hydrogenolyzable group, and the agriculturally acceptable salts of these compounds.
