New routes to phenalenones from 2,7-dihydroxynaphthalene. X-Ray crystal structure of 4-(α-hydroxybenzyl)-2-phenyl-6H-phenaleno-[1,9-bc]pyran-6-one

Abstract

9-Aryl-6-hydroxy-1H-phenalen-1-ones and 2-aryl-4-aroyl-6H-phenaleno[1,9-bc]pyran-6-ones can be obtained by the reaction of 2,7-dihydroxynaphthalene-1-carbaldehyde with acetophenones and by condensation of aroylacetaldehydes with 2,7-dihydroxynaphthalene under acid conditions. Aroylacetaldehydes may be involved in the former reaction also, arising by transfer of the formyl group from the naphthaldehyde to the acetophenone. 2,7-Dihydroxynaphthalene-1-carbaldehyde reacts with 2-hydroxy-acetophenone to form 1H-naphtho[2,1,8-mna]xanthen-1-one.

Interaction of naphthalene-2,7-dioxybismagnesium dibromide with cinnamaldehydes affords 4-benzyl-2-phenyl-6H-phenaleno[1,9-bc]pyran-6-ones.