Metal??Free Oxidative Coupling: Xanthone Formation via Direct Annulation of 2??Aryloxybenzaldehyde using Tetrabutylammonium Bromide as a Promoter in Aqueous …

H Rao, X Ma, Q Liu, Z Li, S Cao…

Index: Rao, Honghua; Ma, Xinyi; Liu, Qianzi; Li, Zhongfeng; Cao, Shengli; Li, Chao-Jun Advanced Synthesis and Catalysis, 2013 , vol. 355, # 11-12 p. 2191 - 2196

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Citation Number: 25

Abstract

Abstract: A metal-free intramolecular annulation of 2-aryloxybenzaldehydes to xanthones is disclosed, which proceeds through the direct oxidative coupling of an aldehyde CÀH bond and aromatic CÀH bonds using tetrabutylammonium bromide (TBAB) as a promoter in aqueous medium. This strategy works smoothly in the presence of both electron-donating and electron-withdrawing groups, and displays good tolerance towards catalytically ...