One-Pot Synthesis of Functionally Enriched Benzo[ b ]fluorenones: An Eco-Friendly Embedment of Diverse 1-Indanones into o -Bis-Ynones.

An efficient, base-promoted, one-pot, metal-free, open-flask synthesis of diverse, functionally enriched benzo[ b ]fluoren-11-ones has been discovered, and wide applicability of this exceptionally simple protocol with green flavors has been scoped. This synthesis proceeds via an unanticipated, tandem, double-aldol condensation between in situ -generated 1-indanone dianions and o -bis-ynones to furnish benzo[ b ]fluoren-11-ones harboring as many as six variegated substituents on their tetracyclic framework. This methodology has also been amplified to access heterocyclic analogues 2- and 4-azabenzo[ b ]fluorenones of benzo[ b ]fluoren-11-ones and extended to mixed linear-angular annulated pentacyclic dibenzo[ a , h ]fluoren-13-one.