obsolete 2-hydroxy-2H-benzo[h]chromene-2-carboxylate isomerase activity (obsolete GO:0018837)
OBSOLETE. Catalysis of the reaction: 2-hydroxy-2 H-benzo[h]chromene-2-carboxylate = cis -4-(1'-hydroxynaphth-2'-yl)-2-oxobut-3-enoate.