1.3.5- Triazine 2,4,6-tris -, ring synthesi

Results concerning these ring systems are summarized in Scheme 52. Synthesis of a benzologue of the [l,2,3]tri-azolo[4,3-triazine ring system has been published by Abbott et al. <2002T3185>. The essence of the cyclization procedure is diazotation of the zwitterionic aminoaryltriazole compound 261, whereupon an internal azo coupling takes place to yield the fused triazine 262 in low yield (24%). 

So we were induced to try this approach, too, and we started synthesis work in the field of s-triazines. The result of our primary working hypothesis was disappointing derivatives bearing anilino radicals showed no herbicidal effects. Surprisingly, however, the herbicidal activity reappeared in the structure 2-chloro-4,6-bis-diethylamino-s-triazine, compound G-25804 shown previously. The awareness that we were confronted with a completely new herbicidal matrix with apparently superior usefulness led us to intensive work around the s-triazine ring system. 

A -Acylchloroformimidamides 7 are suitable building blocks for the synthesis of 1,3,5-tri-azines,411 414 reacting with amidines under mild conditions to provide several monoamino-1,3.5-triazines 8. The reaction presumably proceeds via an initial nucleophilic substitution of the chlorine atom, followed by a ring-closure reaction with the carbonyl carbon of the TV-acyl group 411... 

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