Organocatalyzed reactions between chromones and acetylenedicarboxylates
leading either to xanthone derivatives or to functionalized benzophenones
are described. The outcome of the reactions was found to depend
both on the nature of the chromone substituents and on the basicity
of the organocatalyst.
DMAP - hetero-Diels-Alder reactions - Friedel-Crafts reactions - organocatalysis -
xanthones - zwitterions