Synthesis of Spiro Polycyclic N-Heterocycles and Indolecarbazoles via Merging Oxidative Coupling and Cascade Palladium-Catalyzed Intramolecular Oxidative Cyclization

2024/04/12 by Yu Dong, Mei-Feng Lan, Yue-Qin Lin +10 · 2 citations
Pharmacology, Toxicology and Pharmaceutics · Chemistry · #Bioactive Compounds and Antitumor Agents #Catalytic C–H Functionalization Methods #Axial and Atropisomeric Chirality Synthesis

paper · doi:10.1021/acs.joc.4c00545

Abstract

We report a step-economic strategy for the direct synthesis of spiro polycyclic N-heterocycles and indolecarbazole-fused naphthoquinones by merging oxidative coupling and cascade palladium-catalyzed intramolecular oxidative cyclization. In the protocol, bi-indolylnaphthoquinones were first synthesized by oxidative coupling of indoles and naphthoquinones. Subsequent cascade palladium-catalyzed intramolecular oxidative cyclization of bi-indolylnaphthoquinones gave spiro polycyclic N-heterocycles and indolecarbazoles. The intramolecular oxidative cyclization approach could also be realized by the presence or absence of iron catalysts under standard conditions. This protocol is featured with moderate to excellent yields, a wide substrate scope, and divergent structures of products.

Cited by

• Pd/Ag-Cocatalyzed Merging Intramolecular Oxidative Coupling and Cascade [4 + 2] Cycloaddition: Synthesis and Photophysical Properties of Novel Polycyclic N -Heterocycles Fused Naphthoquinones. [europepmc]
• Base-Regulated Spiroannulation: Insights into the Palladium-Catalyzed [2 + 2 + 1] Annulation of 1,2-Dihaloarenes, Alkynes, and 2‑Naphthol. [europepmc]

Related

• Double Palladium Catalyzed Reductive Cyclizations. Synthesis of 2,2′-, 2,3′-, and 3,3′-Bi-1H-indoles, Indolo[3,2-b]indoles, and Indolo[2,3-b]indoles
• Organocatalytic Enantioselective Synthesis of Chiral Spiro‐indoline‐pyrazolones through a formal [4+1] Annulation Reaction of 4‐Bromopyrazolones and aza‐ortho‐Quinone Methides
• Recyclable Palladium-Catalyzed Carbonylative Cyclization of Aryl Iodides and 2-Hydroxyacetophenones towards Flavones
• Stereoselective one-pot synthesis of spiro-indenoquinoxaline–pyrrolidine hybrids: structural elucidation and biological evaluation
• Visible light-mediated dearomative spirocyclization/imination of nonactivated arenes through energy transfer catalysis