Synthesis of Naphth[2', 3': 4, 5]imidazo[2, 1-b]thiazole-5, 10-diones

Abstract

Tetracyclic azole compounds with an additional thiazole ring fused to naphth[2, 3-cnimidazole4, 9-diones were synthesized. Naphth[2', 3': 4, 5]imidazo[2, 1-b]thiazole-5, 10-diones [15a-k]and [13]-[15] were obtained by cyclodehydration of 2- (2-oxoalkylthio)-1 H-naphth[2, 3-d]imidazole-4, 9-diones [4a-k]. Polyphosphoric acid was used to effect cyclodehydration of [4a-g]. With acetic anhydride and pyridine, [4b] and [4h-i] were found to undergo acetylation and cyclization to form [5g] and [5i]. The reactions of [4j-k] with acetic anhydride gave [5j-k] in the absence of pyridine, but in the presence of pyridine they afforded [14b] and [15]. The effects of the quinone group on the reaction and properties of these compounds are discussed.