Oxidative cyclization of 3‐cinnamoyltropolones with I₂/DMSO/H₂SO₄ system

<jats:title>Abstract</jats:title><jats:p> <jats:boxed-text content-type="graphic" position="anchor"><jats:graphic xmlns:xlink="http://www.w3.org/1999/xlink" mimetype="image/gif" position="anchor" specific-use="enlarged-web-image" xlink:href="graphic/mgra001.gif"><jats:alt-text>magnified image</jats:alt-text></jats:graphic></jats:boxed-text></jats:p><jats:p>In this study, a facile and general method synthesizing flavone‐like 2‐aryl‐4,9‐dihydrocyclohepta[<jats:italic>b</jats:italic>]pyran‐4,9‐diones (<jats:bold>2a</jats:bold>, <jats:bold>2b</jats:bold>, <jats:bold>2c</jats:bold>, <jats:bold>2d</jats:bold>, <jats:bold>2e</jats:bold>, <jats:bold>2f</jats:bold>, <jats:bold>2g</jats:bold>, <jats:bold>2h</jats:bold>, <jats:bold>2i</jats:bold>, <jats:bold>2j</jats:bold>, <jats:bold>2k</jats:bold>, <jats:bold>2l</jats:bold>, <jats:bold>2m</jats:bold>, <jats:bold>2n</jats:bold>, <jats:bold>2o</jats:bold>, <jats:bold>2p</jats:bold>, <jats:bold>2q</jats:bold>, <jats:bold>2r</jats:bold>, <jats:bold>2s</jats:bold>, <jats:bold>2t</jats:bold>, <jats:bold>2u</jats:bold>, <jats:bold>2v</jats:bold>, <jats:bold>2w</jats:bold>, <jats:bold>2x</jats:bold>, <jats:bold>2y</jats:bold>) from 3‐cinnamoyltropolones (<jats:bold>1a</jats:bold>, <jats:bold>1b</jats:bold>, <jats:bold>1c</jats:bold>, <jats:bold>1d</jats:bold>, <jats:bold>1e</jats:bold>, <jats:bold>1f</jats:bold>, <jats:bold>1g</jats:bold>, <jats:bold>1h</jats:bold>, <jats:bold>1i</jats:bold>, <jats:bold>1j</jats:bold>, <jats:bold>1k</jats:bold>, <jats:bold>1l</jats:bold>, <jats:bold>1m</jats:bold>, <jats:bold>1n</jats:bold>, <jats:bold>1o</jats:bold>, <jats:bold>1p</jats:bold>, <jats:bold>1q</jats:bold>, <jats:bold>1r</jats:bold>, <jats:bold>1s</jats:bold>, <jats:bold>1t</jats:bold>, <jats:bold>1u</jats:bold>, <jats:bold>1v</jats:bold>, <jats:bold>1w</jats:bold>, <jats:bold>1x</jats:bold>, <jats:bold>1y</jats:bold>) <jats:italic>via</jats:italic> oxidative cyclization reaction by using I<jats:sub>2</jats:sub>/DMSO/H<jats:sub>2</jats:sub>SO<jats:sub>4</jats:sub> system is described. The method was found to be successfully applicable to a wide range of 3‐cinnamoyltropolone derivatives and characterized by generality, compatibility, and easy work‐up procedures. J. Heterocyclic Chem., (2009).</jats:p>