Pyryliumolate. III. Synthese anellierter Benzotropolone

Pyryliumolates. III. Synthesis of Annulated Benzotropolones Dirhodiumtetraacetate catalyzed nitrogen extrusion from diazocarbonyl compounds (2a–f, 19c, 23d–f, 25b) yields benzopyryliumolates (3), which were trapped intramolecularly in situ to give tetracyclic adducts (4a, 5a–d, 20, 24a–c, 26). Starting with 5a and 5d annulated benzotropolones (12a, d) are accessible.