光气 、 6-Amino-3,4-dihydro-3-oxo-4-(2-propynyl)-2H-1,4-benzoxazine 以to produce the 3,4-dihydro-6-isocyanato-3-oxo-4-(2-propynyl)-2H-1,4-benzoxazine which的产率得到3,4-dihydro-6-isocyanato-3-oxo-4-(2-propynyl)-2H-1,4-benzoxazine
The invention is concerned with compounds of the formula ##STR1## wherein R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5, R.sup.6, R.sup.7, n and X have the significances given in the description, as well as enol ethers and salts thereof and their manufacture. The compounds have herbicidal properties and are accordingly suitable as active ingredients of weed control compositions. The invention is also concerned with weed control compositions containing one or more of such substances as well as the use of the substances or compositions for the control of weeds. Certain starting materials, which also have herbicidal activity, and their production are also described.