An efficient access to the synthesis of novel 12-phenylbenzo[6,7]oxepino[3,4-b]quinolin-13(6H)-one derivatives

Abstract

SummaryAn efficient access to the tetracyclic-fused quinoline systems, 12-phenylbenzo[6,7]oxepino[3,4-b]quinolin-13(6H)-one derivatives 4a–l, is described, involving the intramolecular Friedel–Crafts acylation reaction of 2-(phenoxymethyl)-4-phenylquinoline-3-carboxylic acid derivatives 3a–l aided by the treatment with PPA (polyphosphoric acid) or Eaton’s reagent. The required starting compound (2) was obtained by Friedländer reaction of 2-aminobenzophenone (1) with 4-chloroethylacetoacetate by using CAN (cerium ammonium nitrate, 10 mol %) as catalyst at room temperature. The substrates 3a–l were prepared through one-pot reaction of ethyl 2-(chloromethyl)-4-phenylquinoline-3-carboxylate (2) and substituted phenols. Our developed strategy, involving a three-step route, offers easy access to tetracyclic-fused quinoline systems in short reaction times, and the products are obtained in moderate to good yields.

A Simple and Facile Synthesis of 4‐Phenylquinoline‐fused Pyrrolidin‐2‐ones

“…The progress of reactions was monitored by TLC on silica gel GF254 using ethyl acetate/petroleum ether (1:3) as the eluent. Ethyl 2‐(chloromethyl)‐4‐phenylquinoline‐3‐carboxylate ( 1 ) was prepared according to the method of the literature , and the amines 2a–l used were obtained from Fluka without further purification.…”

Transition metal-free one-pot synthesis of nitrogen-containing heterocycles

“…The process involves a series of chemical events such as intermolecular addition of alkyne to in situ generated imine/ring-closure followed by oxidative aromatization (Scheme 78). An operationally simple and metal-free methodology for synthesis of tetracyclic-fused quinolines has been introduced by Gao et al [173] involving the Friedlander reaction of benzophenone derivatives 270 and substituted ethylacetoacetates 271 (Scheme 79, Path A). Silica-supported P 2 O 5 catalytic system was developed for synthesis of quinoline derivatives via the Friedlander annulation reaction of benzophenones 270 and ethylacetoacetates 271 in 15-40 min.…”

Synthesis of benzofurans from the cyclodehydration of α-phenoxy ketones mediated by Eaton’s reagent

“…47 The P 2 O 5 –MeSO 3 H combination is known as Eaton’s reagent, 48 which is an alternative reagent to polyphosphoric acid (PPA) for the promotion of (cyclo)dehydration reactions. 49–54 Herein, we have applied Eaton’s reagent to mediate the synthesis of 3-substituted or 2,3-disubstituted benzofurans efficiently under mild conditions.…”