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

ABSTRACT: 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. Upon developing a rapid and efficient synthesis of 2,1-borazaronaphthalenes starting from simple, readily available starting materials,1 we subsequently developed the Suzuki− Miyaura cross-coupling of brominated 2,1-borazaronaphtha