Transition‐Metal‐Free Synthesis of Acridones via Base‐Mediated Intramolecular Oxidative C−H Amination

Abstract

Intramolecular oxidative CÀH amination of 2-aminobenzophenones was achieved in the presence of potassium tert-butoxide and dimethyl sulfoxide. A series of functionalized acridones were prepared in moderate to excellent yields in a mild, efficient, and transition-metal-free manner.

Metal‐Free Synthesis of Alkenylazaarenes and 2‐Aminoquinolines through Base‐Mediated Aerobic Oxidative Dehydrogenation of Benzyl Alcohols

“…Literature cites the formation of such product oxidative CÀ H amination of 2aminobenzophenone in the presence of KO t Bu and DMSO. [18] However, when the same reaction was performed in the presence of KOH, we isolated the required 2-amino-3,4,diphenylquinoline 14 in 25 % yield together with the 2-aminobenzophenone 15 but with no trace of acridin-9(10H)-one.…”

“…Accordingly, when (2‐aminophenyl)(phenyl)methanol 12 was subjected to reaction with 9 a in the presence of CsOH.H 2 O, we isolated acridin‐9(10 H )‐one 13 as the major product in 30 % yield (Scheme 6). Literature cites the formation of such product oxidative C−H amination of 2‐aminobenzophenone in the presence of KO t Bu and DMSO [18] …”

Base-Controlled Synthesis of Fluorescent Acridone Derivatives via Formal (4 + 2) Cycloaddition

“…Generally, the classical approaches to constructing acridones rely on C–C or C–N bond formation through C–H activation and intramolecular cyclization of 2-amino benzophenones or N -arylsubstituted acids, esters, aldehydes, or ketones, intermolecular cyclization of arylboronic acids and o -aminoacetophenones or anthranils, palladium/copper cocatalyzed carbonyl insertion of diarylamines with CO, in addition to several other methods . As is well-known, arynes generated from 2-(trimethylsilyl)­aryl triflates have been employed as powerful and prominent building blocks for the synthesis of heteroaromatic compounds .…”

K2CO3-Catalyzed Dual C–C-Coupled Cyclization to 3-Amino-4-benzoylbiphenyls and In Situ I2-Catalyzed C–N Bond Forming Annulation: A Metal-Free Synthesis of Arylacridones

“…In 2018, Zhang’s group reported a Cu­(NO 3 ) 2 (0.5 equiv)-mediated synthesis of acridones through intermolecular Suzuki cross-coupling of O-amino acetophenone and aryl boronic acid (Scheme a) . Zou and co-workers described the construction of acridones involving C–H amination using three equivalents of t-BuOK (Scheme b) . We were curious to synthesize C-aryl-substituted acridones for their possible material application.…”