| Abstract: | A modified three-component reaction of arylamines, cyanoguanidine, and acetone is described, wherein formation of anomalous guanidinoquinazoline byproducts is greatly enhanced at the expense of the normal dihydro-s-triazines. Four new guanidinoquinazolines and four new dihydro-s-triazines were synthesized via this modification, starting from 2,4-, 2,5-, 3,4-, and 3,5-dimethoxyaniline. The guanidinoquinazoline to dihydro-s-triazine ratio was much higher with 3,4- and 3,5-dimethoxyaniline than with 2,4-dimethoxyaniline. 2,5-Dimethoxyaniline gave an unexpectedly low yield of guanidinoquinazoline, apparently because of steric hindrance. The modified three-component synthesis was also examined in detail with 2-naphthylamine. |
