Divergent Synthesis of 2-Chromonyl-3-hydrazono-chromones and 2-Alkoxy-3-hydrazono-chromones through Switchable Annulation Reactions of <i>o</i>-Hydroxyphenylenaminones with Aryldiazonium Salts
Siyu Song, Menglin Peng, Zhilai Zhang, Huimin Hu, Yuanzheng Wei, Sheng‐Jiao Yan, Yongchao Wang, Fuchao Yu
Abstract
An unprecedented selective chromone annulation reaction controlled by solvent for the divergent synthesis of two types of 2,3-disubstituted chromone skeletons has been developed. A variety of 2-chromonyl-3-hydrazono-chromones and 2-alkoxy-3-hydrazono-chromones were constructed efficiently from readily available o -hydroxyphenylenaminones ( o -HPEs) and aryldiazonium salts at room temperature. This strategy is highly chemoselective and features mild reaction conditions, broad substrate scope, broad functional group tolerance, easy gram-scale preparation, and simple filtration to obtain the pure products without tedious column chromatography.