Formation of Phenalenone Skeleton by an Unusual Rearrangement Reaction

The frame rearrangement
reaction of dinaphthyl ketones, possessing
hydroxy groups at appropriate positions, into phenalenone derivatives
under acidic conditions was discovered serendipitously. Although this
rearrangement had limited scope, its mechanism was unusual, involving
the division of naphthalene rings into one phenalenone ring and one
benzene ring. The reaction mechanism was elucidated by direct determination
of intermediate structures using 1H NMR measurements. The
generated phenalenones are expected to be key intermediates toward
natural products and functional materials.