Dearomatization of Halonaphthols via an Intermolecular [4+1] Spiroannulation with in situ Formed Aza-ortho-quinone Methides

A base promoted dearomatization strategy for [4+1] spiroannulation of halonaphthols with N-(o-chloromethyl) aryl amides is reported, which is used to efficiently synthesize azaspirocycles. A range of azaspirocycles were obtained in satisfactory to excellent yield with high diastereoselectivity under mild conditions. Variety functional groups including aldehyde and free hydroxyl group, and different N-protecting groups, such as Bz and Ts are compatibility. The transformation of the product and a possible mechanism were also provided.