synthesis of heteroaromatic compounds by oxidative aromatization using an activated carbonmolecular oxygen systemheteroaromatic化合物的合成氧化芳构化使用激活carbonmolecular氧气系统.pdf

Molecules 2009, 14, 3073-3093; doi:10.3390/molecule OPEN ACCESS molecules ISSN 1420-3049 /journal/molecules Review Synthesis of Heteroaromatic Compounds by Oxidative Aromatization Using an Activated Carbon/Molecular Oxygen System Yuka Kawashita and Masahiko Hayashi * Department of Chemistry, Graduate School of Science, Kobe University, Kobe 657-8501, Japan; E-mail: mhayashi@kobe-u.ac.jp (Y.K.) * Author to whom correspondence should be addressed; E-mail: mhayashi@kobe-u.ac.jp Received: 6 July 2009; in revised form: 31 July 2009 / Accepted: 10 August 2009 / Published: 14 August 2009 Abstract: A variety of heteroaromatic compounds, such as substituted pyridines, pyrazoles, indoles, 2-substituted imidazoles, 2-substituted imidazoles, 2-arylbenzazoles and pyrimidin-2(1H)-ones are synthesized by oxidative aromatization using the activated carbon and molecular oxygen system. Mechanistic study focused on the role of activated carbon in the synthesis of 2-arylbenzazoles is also discussed. In the final section, we will disclose the efficient synthesis of substituted 9,10-anthracenes via oxidative aromatization. Keywords: oxidation; aromatization; heteroaromatic compound; activated carbon 1. Introduction 1.1. Activated carbon—O oxidation system; How we discovered it! 2 The oxidation of alcohols to carbonyl compounds is one of the most fundamental reactions in organic synthesis [1]. In 1999, we first reported a Pd/C—ethylene system for the oxidation of benzylic