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.