Annulative π‐Extension by Rhodium(III)‐Catalyzed Ketone‐Directed C−H Activation: Rapid Access to Pyrenes and Related Polycyclic Aromatic Hydrocarbons (PAHs)

• Published in: Angewandte Chemie International Edition 2023-07, Vol.62 (30), p.e202305258-n/a
• Main Authors: Sk, Md Raja, Bhattacharyya, Arya, Saha, Shuvendu, Brahma, Arpita, Maji, Modhu Sudan
• Format: Article
• Language: English
• Subjects: Alkynes; Annulation; APEX; Carbonyl compounds; Carbonyls; C−H Activation; Dehydration; Graphene; Ketones; Polycyclic Aromatic Hydrocarbon; Polycyclic aromatic hydrocarbons; Pyrene; Pyrenes; Rhodium; Synthesis
• ISSN: 1433-7851; 1521-3773
• DOI: 10.1002/anie.202305258

Annulative π‐extension (APEX) reaction has become a powerful tool for the precise synthesis of well‐defined polycyclic aromatic hydrocarbons (PAHs) such as nanographene, graphene, and other PAHs possessing unique structure. Herein, an APEX reaction has been realized at the masked bay‐region for the efficient and rapid synthesis of valuable PAH, pyrene, bearing substitutions at the most challenging K‐region. RhIII‐catalyzed ketone‐directed C−H activation at the peri‐position of a naphthyl‐derived ketone, alkyne‐insertion, intramolecular nucleophilic attack at the carbonyl‐group, dehydration, and aromatization steps occurred in one‐pot to effectuate the protocol. Employing this strategy, a two‐fold APEX reaction on enantiopure BINOL‐derived ketones provided access to axially‐chiral bipyrene derivatives. The detailed DFT study to support proposed mechanism, and synthesis of helical PAHs like dipyrenothiophene and dipyrenofuran are other highlights of the present study. An annulative π‐extension (APEX) method is reported to build a benzene ring at the masked bay‐region of polycyclic aromatic hydrocarbons (PAHs) under RhIII‐catalysis. This one‐pot, ketone‐directed C−H activation/annulation reaction between a ketone and an alkyne selectively provides challenging 4,5‐disubstituted pyrenes, and optically pure bipyrene derivatives.