THIAZOLO[5,4-B]ACRIDINES AND THIAZOLO[4,5-B]ACRIDINES - PROBABLE PHARMACOPHORES OF ANTIVIRAL AND ANTITUMOR MARINE ALKALOIDS

Structural simplification of pentacyclic and hexacyclic antiviral and anti-tumor acridine alkaloids such as dercitin, cyclodercitin and kuanoniamine led to the identification of the thiazolo[5,4-b]acridine or the isomeric thiazolo[4,5-b]acridine nucleus as the putative pharmacophore. Synthetic approaches towards these tetracyclic ring systems and regiochemistry of thiazole ring in cyclodehydration reactions are discussed.