TFA-mediated tandem Friedel-Crafts alkylation/cyclization/hydrogen transfer process for the synthesis of flavylium compounds

…, L Liu, YL Liu, D Wang, YJ Chen

Index: Wu, Yan-Chao; Liu, Li; Liu, Yu-Liang; Wang, Dong; Chen, Yong-Jun Journal of Organic Chemistry, 2007 , vol. 72, # 24 p. 9383 - 9386

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Citation Number: 34

Abstract

The tandem reaction of phenols and chalcones in refluxing TFA gave the flavylium species of 2-hydroxy-2-phenyl-2 H-chromenes in moderate to good isolated yields. The reaction was proposed to involve a tandem transformation of Friedel-Crafts alkylation, dehydrative cyclization, intermolecular hydrogen transfer, and hydration. As a multifunctional catalyst, TFA mediated the processes efficiently and cleanly.