Substituted 2,4-diaminoquinazolines and 2,4-diamino-8-alkylpurines as antagonists of the neurokinin-2 (NK2) receptor

Modification of the heterocyclic nucleus of a lead pyrrolopyrimidine (1) found to be active as an antagonist at the neurokinin-2 (NK2) receptor is described. Compounds based on the purine nucleus (3) were found to be particularly interesting, and were modified in the C(2), C(4) and C(8) substituents to afford compounds with high potency.