Visible-light-induced iminyl radical formation via electron-donor–acceptor complexes: a photocatalyst-free approach to phenanthridines and quinolines

Abstract

A visible light-induced synthesis of nitrogen-containing arenes from O-2,4-dinitrophenyl oximes has been reported. This photochemical strategy is photocatalyst-free and enabled by electron-donor–acceptor (EDA) complexes of O-2,4-dinitrophenyl oximes and Et3N.

Electron Donor‐Acceptor Complexes in Perfluoroalkylation Reactions

“…Chen and colleagues[20a] have uncovered the use of N , N , N′,N′ ‐tetraethylethylenediamine (TEEDA) as base in the EDA complex formation with R F –I towards the perfluoroalkylation of olefins and alkynes,[20b] employing a commercial fluorescent lamp (CFL, 25 W) as irradiation source . The scope of the transformation is depicted in Scheme .…”

“…Thus ruthenium and iridium salts with pyridine‐derived ligands {i.e. : [Ru(bpy) 3 Cl 2 ], ruthenium‐tris(2,2′‐bipyridyl) dichloride and [Ir(dtbbpy)(ppy) 2 ]PF 6 , (4,4′‐Di‐ tert ‐butyl‐2,2′‐bipyridine)bis[(2‐pyridinyl)phenyl]iridium(III) Hexafluorophosphate and others} are among the most popular metal‐organo photocatalysts to achieve an array of synthetic organic transformations , . However, metal complexes are expensive and can cause toxicity issues arising from metal residues when employed in the synthesis of medicinal targets.…”

Radical Transformations towards the Synthesis of Quinoline: A Review

“…Initially, electron-deficient o-benzoyl oximes 56 (electron acceptors), were prepared as per the literature, [88] further irradiated with triethylamine and acetonitrile in the presence of blew LEDs (5 W) for 17 h to afford the desired quinoline 57 in excellent yield. [89] (Scheme 23) The reaction follows a radical chain mechanism, the aryl oxime reacts with ET 3 N to form EDA complex, further undergoes a photocatalyzed single electron transfer to give iminyl radical, [90] which underwent as intramolecular cyclization followed by deprotonation to provide corresponding quinoline product in more generous yields.…”

Photocatalyzed syntheses of phenanthrenes and their aza-analogues. A review

“…In this case, the reaction was photoorganocatalyzed by eosin Y and took place in the presence of an excess (3 equiv) of a sacrificial donor, such as iPr 2 NEt [79]. Later, it was discovered that phenanthridines could be formed starting again from O-2,4-dinitrophenyloximes under photocatalyst-free conditions, by exploiting the capability of these oximes to form visible light absorbing EDA (electron donor-acceptor) complexes with Et 3 N. Thus, a good variety of highly functionalized phenanthridines was prepared in excellent yields [80].…”