Accessing 2,1-Borazaronaphthols: Self-Arylation of 1‑Alkyl-2-aryl-3-bromo-2,1-borazaronaphthalenes

Unlike
their B-alkyl counterparts, brominated N-alkyl B-aryl 2,1-borazaronaphthalenes
undergo a self-arylation reaction in the presence of a catalytic amount
of palladium and base, in which the azaborine serves as both the electrophile
and the nucleophile. The products of the self-arylation are air- and
moisture-stable 2,1-borazaronaphthols, previously only observed in
basic alcoholic solvents. The steric encumbrance of the azaborine
appears to prevent formation of the corresponding boron acid anhydride,
allowing access to a family of 2,1-borazaronaphthol derivatives.