6-heterocyclyl-1-(substituted phenyl)benzotriazole herbicidal agents

A method for the preparation of a compound having the structural formula ##STR89## wherein R is hydrogen, halogen or C.sub.1 -C.sub.4 alkyl;

• and
• R.sub.16 and R.sub.17 are each independently hydrogen,
• C.sub.1 -C.sub.6 alkyl optionally substituted with one or more halogen atoms, or
• C.sub.3 -C.sub.6 cycloalkyl optionally substituted with one or more halogen atoms, and
• when R.sub.16 and R.sub.17 are taken together with the atoms to which they are attached, they may form a ring in which R.sub.16 R.sub.17 is a C.sub.2 -C.sub.5 alkylene group optionally substituted with one to three methyl groups or one or more halogen atoms,
• which comprises:
• reducing a first compound having the structural formula ##STR90## wherein R is as described above with iron in the presence of an organic acid to form a second compound having the structural formula ##STR91## wherein R is as described above, cyclizing the second compound with sodium nitrite in the presence of an organic acid to form a third compound having the structural formula ##STR92## wherein R is as described above, reacting the third compound with aqueous acid to form a fourth compound having the structural formula ##STR93## wherein R is as described above, reacting the fourth compound with an anhydride compound having the structural formula ##STR94## wherein R.sub.16 and R.sub.17 are as described above to form a fifth compound having the structural formula ##STR95## wherein R.sub.16 and R.sub.17 are as described above, and reacting the fifth compound with boron tribromide.