An efficient synthesis of (NH)-phenanthridinones via ligand-free copper-catalyzed annulation

Abstract

An efficient and concise procedure for the ligand-free copper-catalyzed cascade reaction of C–O and C–N bond coupling was developed to afford various (NH)-phenanthridinones.

Synthesis of N-Heterocycles via Transition-Metal-Catalyzed Tandem Addition/Cyclization of a Nitrile

“…Later, the same research group extended this copper catalytic tandem reaction to synthesize free NH-phenanthridinones by using biarylnitrile species as the substrates (Scheme 7). 16 Specifically, the reaction operates under ligand-free catalytic conditions and provides the desired products as versatile structures with high to excellent yields. Besides, the authors have indicated that the reac- Four amaryllidaceae alkaloids with similar structures can be obtained easily by further transformations of crinasiadine in one to four more synthetic steps (Scheme 8).…”

Copper-Catalyzed Dual Cyclization for the Synthesis of Quinindolines

“…In this respect, our recent work in the synthesis of norneocryptolepine derivatives through a Pd-catalysis can systematically offer the unprotected quinindolines various substituents on the benzene moieties ( Scheme 1 ) [ 22 ]. This work and our experience in the construction of heterocycles [ 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 ] encouraged us to continuously study in this field. In addition, during the investigation of optimized conditions, we found the possibility to proceed with the dual cyclization under a Cu/Lewis acid catalytic system.…”

Microwave‐Assisted Decarbonylative Coupling Reaction of o‐Halobenzamides for Phenanthridinone Synthesis

“…In addition, the insertion reactions of o ‐aryl anilines with CO, CO 2 or N,N ‐dimethyl formamide have also been disclosed as feasible approaches for the efficient synthesis of phenanthridinones. Furthermore, the intramolecular cyclization of functional o ‐phenyl benzamides, 2′‐bromo‐[1, 1′‐biphenyl]‐2‐carbonitriles, N ‐aryl 2‐halobenzaimides, N ‐phenyl benzamides have been proved to be practical tools toward the construction of these heterocycles, too. The coupling reactions of aryl carbamic chlorides with aryl iodides, o ‐halobenzoates and o ‐haloanilines, N ‐formyl o ‐haloanilines and benzynes, as well as ring expansion of spirolactam etc constitute even extended synthetic routes.…”