Hydride-Induced Anionic Cyclization: An Efficient Method for the Synthesis of 6-H-Phenanthridines via a Transition-Metal-Free Process

Abstract

A novel procedure for hydride-induced anionic cyclization has been developed. It includes the reduction of a biaryl bromo-nitrile with a nucleophilic aromatic substitution (S(N)Ar). A range of polysubstituted 6-H-phenanthridines were so obtained in moderate to good yield with good substrate tolerance. This method involves a concise transition-metal-free process and was applied to synthesize natural alkaloids.

Cascade C–C and C–N Bond Formation: A Straightforward Synthesis of Phenanthridines and Fused Quinol­ines

“…8‐(Trifluoromethyl)phenanthridine (3e): 18 Compound 3e was prepared according to the general experimental procedure as above, yield 0.215 g (87 %); white solid; m.p. 96–99 °C.…”

“…3‐Fluorophenanthridine (3u): 18 Compound 3u was prepared according to the general experimental procedure as above, yield 0.177 g (90 %); white solid. 1 H NMR (500 MHz, CDCl 3 ): δ = 9.26 (d, J = 7.7 Hz, 1 H), 8.39–8.63 (m, 2 H), 8.01 (s, 1 H), 7.75–7.92 (m, 2 H), 7.60–7.74 (m, 1 H), 7.32–7.54 (m, 1 H) ppm.…”

Vanadium(V) Complex-Catalyzed One-Pot Synthesis of Phenanthridines via a Pictet-Spengler-Dehydrogenative Aromatization Sequence

“…Phenanthridine was first synthesized from the reaction between benzaldehyde and aniline in 1889 [6], and a number of preparative methods have been reported to date [1,[7][8][9]. However, since most protocols necessitate harsh reaction conditions and/or multi-step reaction sequences from commercially available starting materials [10,11], concise and mild preparation procedures for this important class of compounds are still in high demand [12][13][14][15].…”

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.…”