Synthesis of 4-arylaminoquinazolines from 2-amino-n'-arylbenzamidines and orthoesters via the dimroth rearrangement of intermediate quinazolin-4(3h)-imines

A reaction of 2-amino-N'-arylbenzamidines with triethyl orthoformate, orthoacetate and orthopropionate leads to quinazolin-4(3H)-imines. These compounds transform to 4-arylaminoquinazolines by heating in acetic acid according to the Dimroth rearrangement mechanism. Unexpectedly, these imines heated in ethanol gave mixtures of 4-arylaminoquinazolines and 4-ethoxy-quinazoline.