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M. E. Zwaagstra, H. Timmerman, A. C. Van De Stolpe, F. J. De Kanter, M. Tamura, Y. Wada and M. Q. Zhang, “Synthesis and Structure-Activity relatIonships of Carboxyflavones as Structurally Rigid CysLT1 (LTD4) Receptor Antagonists,” Journal of Medicinal Chemistry, Vol. 41, No. 9, 1998, pp. 1428-1438. doi:10.1021/jm970179x

has been cited by the following article:

• TITLE: A Facile Synthesis of 9,10-Dimethoxybenzo[6,7]- ox-epino[3,4-b]quinolin-13(6H)-one and Its Derivatives

  AUTHORS: Dingqiao Yang, Xiuli Liang, Xiongjun Zuo, Yuhua Long

  KEYWORDS: The Intramolecular Friedel-Crafts Acylation Reaction: 9, 10-Dimethoxybenzo; [6, 7]oxepino[3, 4-b]quinolin-13(6H)-one and Its Derivatives; 6, 7-Dimethoxy-2-(phenoxymethyl)quinoline-3-carboxylic Acid: Ethyl; 6, 7-dimethoxy-2-(phenoxymethyl)quinoline-3-carboxylate: PPA

  JOURNAL NAME: International Journal of Organic Chemistry, Vol.3 No.2, June 13, 2013

  ABSTRACT: A concise and efficient method for the synthesis of novel 9,10-imethoxybenzo[6,7]oxepino[3,4-b]quinolin13(6H)-one and its derivatives 7a-p has been developed via the intramolecular Friedel-Crafts acylation reactions of 6,7-dimethoxy-2-(phenoxymethyl)quinoline-3-carboxylic acids 6a-p with polyphosphoric acid (PPA) as catalyst and solvent under mild conditions. The key intermediates 6a-p were prepared through the in situ formation of ethyl 6,7-dimethoxy-2-(phenoxymethyl)quinoline-3-carboxylates 5a-p followed by hydrolysis with aqueous ethanolic sodium hydroxide solution. The novel synthetic method has the advantages of good yields, easy work-up, and environmentally friendly character, which may provide a novel highly efficient process for making quinoline and related azaheterocycle libraries.