Synthesis of 6,8-Diarylimino-7H-Pyrano[3,2-c:5,6-c’]Dicoumarins; Chemoselective Hydrolysis of the Ether- and Imino-Functions

Abstract

POCl3-induced dehydration of 3,3'-methylenedi(2-arylamino-4 H-chromen-4-ones) gives 6,8-diarylimino-7 H-pyrano[3,2- c:5,6- c’]dicoumarins, which undergo chemoselective hydrolysis of the imino function to form 7 H-pyrano[3,2- c:5,6- c’]dicoumarins by heating with HCl in methanol However, cleavage of the ether function occurs upon heating in acetic acid to give 3,3'-methylenedi(2-arylamino-4 H-chromen-4-ones).