Theoretical Investigation on TfOH Catalyzed Cascade Cyclization Reaction with Conjugated 1,5-Enyneto Construct Benzo[b]-Fluorenone and Benzo[de]Anthracen 7-One

Abstract

Abstract: Our DFT calculation provided the first theoretical investigation on TfOH-mediated cascade cyclization from ethyl (E)-2-(2,3-diphenyl-1H-inden-1-ylidene)acetate. The triple bond was activated via protonation forming carbocation intermediate followed by rate-limiting 6-endo-dig cyclization resulting in six-membered ring. The naphthalene ester was generated via aromatization and concomitant recover of TfOH. The ester group is activated under acidic condition, from which two paths are competitive not only from similar barriers but relative energy of counterparts. One is intramolecular acylation from the first aromatic ring followed by dealcoholation producing major benzofluorenone product. The alternative from counterpart is via retro-Friedel−Crafts C−C cleavage and subsequent intramolecular acylation by a third aryl ring furnishing another benzo[de] anthracen-7-one product.

Keywords: Benzofluorenone; Cascade Cyclization; 1,5-Enyne; 6-Endo-Dig; Intramolecular Acylation

Citation

Nan Lu. Theoretical Investigation on TfOH Catalyzed Cascade Cyclization Reaction with Conjugated 1,5-Enyneto Construct Benzo[b]-Fluorenone and Benzo[de]Anthracen-7-One. WebLog J Mol Cell Biol. wjmcb.2025.i2607. https://doi.org/10.5281/zenodo.17290903