Imidazonaphthothiazole derivatives 3-6 were prepared by treatment of 2-aminonaphtho[2,3-d]-thiazole-4,9-dione(1) with phenacyl bromide, chloroacetic acid, diethyl oxalate and 2,3-dichloroquinoxaline respectively. The reaction of 1 with ethyl acrylate, ethyl acetoacetate and diethyl malonate gave the corresponding naphthothiazolopyrimidine derivatives 8-11.