Rapid Assembly of Spiroisoxazolidines by [4 + 1] Dearomative Spiroannulation of α-Bromo-β-naphthol and Nitroolefin.

A novel [4 + 1] dearomative spiroannulation of α-halo-β-naphthol and nitroolefin has been developed for the direct construction of various spiroisoxazolidines in high chemo- and diastereoselectivity. Notably, halophenols (X = Cl and I) were also tolerated by this reaction. This transformation was realized through a sequence of electrophilic dearomatization/dehalogenation, and mechanistic studies revealed that different routes occurred for C(sp 3 )-X bond cleavage. Moreover, the potential application of this method was exemplified by several further transformations.