A metal-free visible-light photoredox-catalyzed intermolecular cyclization reaction of O-2,4-dinitrophenyl oximes to phenanthridines was developed. In this study, the organic dye eosin Y and i-Pr₂NEt were used as photocatalyst and terminal reductant, respectively. The oxime substrates were transformed into iminyl radical intermediates by single-electron reduction, which then underwent intermolecular
Synthesis of Phenanthridines and Analogues via Suzuki Coupling and Condensation
作者:Jayanta Ray、Shubhendu Dhara、Munmun Ghosh
DOI:10.1055/s-0033-1339793
日期:——
A convenient and short methodology has been developed towards the synthesis of highly substituted phenanthridines and their analogous benzo[k] and benzo[i] derivatives in a single step viaSuzukicoupling and condensation between suitably substituted aromatic ortho-bromoaldehydes and ortho-aminobenzeneboronic acids in good to excellent yields.
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 (SNAr). 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.