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Synthesis 2018; 50(16): 3169-3176
DOI: 10.1055/s-0037-1610139
special topic
© Georg Thieme Verlag Stuttgart · New York

A Metal-Free Synthesis of 3-Phenoxyimidazo Heterocycles by Catalytic Oxidative Cyclization of 2-Amino-azaarenes with Lignin Models

Authors


We gratefully acknowledge the National Natural Science Foundation of China (NSFC) (21502037, 21373073, and 21672048) and the Pandeng Plan Foundation of Hangzhou Normal University for Youth Scholars of Materials, Chemistry and Chemical Engineering for financial support. G. Z. acknowledges a Qianjiang Scholar award from Zhejiang Province, China.
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Publication History

Received: 28 February 2018

Accepted after revision: 09 April 2018

Publication Date:
23 May 2018 (online)

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† Y. C. and S. W. contributed equally to this work

Published as part of the Special Topic Modern Coupling Approaches and their Strategic Applications in Synthesis

Abstract

A metal-free catalytic oxidative cyclization of 2-aminopyridines and 2-aminobenzothiazole with lignin model 2-phenoxyacetophenones was developed, in which inexpensive iodine was used as the catalyst and tert-butyl hydroperoxide (TBHP) was the oxidant. The reaction proceeded smoothly under an air atmosphere to produce valuable 3-phenoxyimidazo[1,2-a]pyridines and 3-phenoxybenzo[d]imidazo[2,1-b]thiazoles, respectively, in moderate to good yields.

Key words

metal-free - oxidative cyclization - lignin model - 2-phenoxyacetophenone - imidazo[1,2-a]pyridine - benzo[d]imidazo[2,1-b]thiazole

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