Synthesis of Dihydro‐5H‐Benzo[c]‐Fluorenes, Dihydroindeno[c]‐Chromenes and Thiochromenes via Intramolecular Cyclization and their Effect on Human Leukemia Cells

Abstract In this work, we describe the construction of a series of 6,7‐dihydro‐5H‐benzo[ c ]fluorenes. Their synthesis is based on an intramolecular‐cyclization of tricyclic substrates, which has an alcohol functional group in acidic conditions at ambient temperature. Certain reaction optimization conditions reveal that triflic acid was the most convenient reagent for this transformation, affording a broad range of fluorene derivatives in a 37 to 93% yield. We illustrate the robustness of this methodology through a gram‐scale synthesis, and the preparation of dihydroindeno[ c ]‐chromenes thiochromenes, and azulenes derivatives. magnified image