Synthesis of 3-(quinolin-2-yl)- and 3,6-bis(quinolin-2-yl)-9H-carbazoles

A new approach toward the synthesis of 2,4-bis(fluoroalkyl)-substituted quinoline derivatives using fluoroalkyl amino reagent chemistry

The present work describes the unprecedented use of Fluoroalkyl Amino Reagents (FARs) to afford 2,4-bis(fluoroalkyl)-substituted quinoline derivatives in two steps under mild reaction conditions, in good yields and with a very good regioselectivity.

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

An 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 novel and facile synthesis of 3-(2-benzofuroyl)- and 3,6-bis(2-benzofuroyl)carbazole derivatives

A facile synthesis of hitherto unreported 3-(2-benzofuroyl)carbazoles 3a-k, 3,6-bis(2-benzofuroyl)carbazoles 5a-k, and naphtho[2,1-b]furoylcarbazoles 3l and 5l is described. The synthesis mainly relies on the ultrasound-assisted Rap-Stoermer reaction of 3-chloroacetyl- (1) or 3,6-dichloroacetyl-9-ethyl-9H-carbazole (4) with various salicylaldehydes 2a-k as well as 2-hydroxy-1-naphthaldehyde (2l) in CH(3)CN with the presence of PEG-400 as catalyst. The procedure offers easy access to benzofuroylcarbazoles in short reaction times and the products are obtained in moderate to good yields.

First synthesis of 2-(benzofuran-2-yl)-6,7-methylene dioxyquinoline-3-carboxylic acid derivatives

A facile and inexpensive synthesis of a series of novel methylenedioxy-bearing 2-(benzofuran-2-yl)-quinoline-3-carboxylic acid derivatives 3a-h via the one-pot reaction of ethyl 2-chloromethyl-6,7-methylenedioxyquinoline-3-carboxylate (5) with various substituted salicylaldehydes 6a-g as well as 2-hydroxy-1-naphthaldehyde (6h) is described. Substrate 5 was synthesized by the Friedländer condensation reaction of 2-amino-4,5-methylenedioxybenzaldehyde (4) with ethyl 4-chloro-3-oxobutanoate using KHSO(4) as catalyst under ultrasound irradiation conditions. The targeted compounds 3a-h were obtained in good yields of 52-82% and their structures were established based on spectral data and elemental analyses.