Tricyclic Systems: Central Carbocyclic Ring with Fused Five- and Six-membered Rings

Abstract

This chapter on tricyclic ring systems with a central carbocyclic ring and fused five- and six-membered heterocyclic rings focuses on a handful of specialized classes of compounds that are clearly representative of the title compounds as a whole. Updating material from the corresponding chapter in CHEC-II(1996), the chemistry of the imidazo[4,5-g]quinazoline-based benzo-separated purines, the furo[2,3-h]benzopyran- and furo[3,2-g]chromene-based furocoumarins and furochromones, the pyrrolo[3,2-g]isoquinoline-based tetracyclic ellipticines, and the pyrrolo[2,3-f]quinoline-based PQQ and related compounds are examined. These are especially important classes of compounds with specialized applications, and with syntheses that are instructive in the state-of-the-art methods for preparing tricyclic heterocycles with a central carbocyclic rings in general. In addition, a new section on the syntheses of imidazo- and triazoloquinolines has been included, as the syntheses and reactions of these particular tricyclics (not covered in CHEC-II(1996)) highlight important chemical transformations widely applicable to the title compounds as a whole. Altogether, with 201 structures, 30 Schemes, and 68 references citing journal articles mainly from the period 1996–2006, this chapter provides a detailed and informative overview of tricyclic ring systems with a central carbocyclic ring.