The synthesis of new substituted 6H-imidazo[1,2-c]quinazolin-5-ones (2
) is described. 3-Substituted 6H-imidazo[1,2-c]quinazolin-5-ones (3) u
ndergo a Dimroth-type rearrangement to the thermodynamically more stab
le 2-substituted 6H-imidazo[1,2-c]quinazolin-5-ones (4).