Studies on the oxidative cyclization of 3-hydroxyalkyl-1,2,4-trialkoxynaphthalenes and synthetic application for the biologically active natural compound rhinacanthone
作者:Tokutaro Ogata、Misae Doe、Aya Matsubara、Eri Torii、Chiaki Nishiura、Arisa Nishiuchi、Yusuke Kobayashi、Tetsutaro Kimachi
DOI:10.1016/j.tet.2013.11.025
日期:2014.1
The oxidative intramolecular cyclization of 3-hydroxyalkyl-1,2,4-trimethoxynaphthalenes was investigated. A series of 1,2-naphthoquinone fused cyclic ethers were synthesized directly from 3-hydroxyalkyl-1,2,4-trimethoxynaphthalenes by exposure to diammonium cerium (IV) nitrate. To understand the reaction mechanism, the intramolecular cyclization of 3-hydroxyalkyl-naphthoquinones that were formed as reaction intermediates was also examined. The results suggested that the reaction proceeds by a stepwise oxidation-cyclization mechanism. Using this methodology, five-step synthesis of rhinacanthone was achieved with high yield. (C) 2013 Elsevier Ltd. All rights reserved.