A new efficient synthesis of highly functionalized alizarins from alizarin, acetylenic esters, and isocyanides

Abstract

The reactive intermediates generated by the addition of isocyanides to dialkyl acetylenedicarboxylates were trapped by alizarin to produce dialkyl 2-alkyl (aryl) amino-6,11-dihydro-12-hydroxy-6,11-dioxo-4H-naphtho [2,3-g]chromene-3,4-dicarboxylates in good yields. When the reactions were carried out in the presence of ethyl propiolate as acetylenic component, ethyl 4-alkyl (aryl) imino-4-(9,10-dihydro-1-hydroxy-9,10-dioxoanthracen-2-yloxy)but-2-enoates were obtained.