Alkali-metal mediated reactivity of a diaminobromoborane: mono- and bis-borylation of naphthalene versus boryl lithium or hydroborane formation

Reaction of lithium with PDABBr [PDA = C(6)H(4)-1,2-(NTripp)(2), Tripp = 2,4,6-Pr(i)(3)C(6)H(2)] and naphthalene afforded 2- and 2,6-borylated naphthalenes; conversely, use of high-sodium lithium (0.5% Na) afforded the lithium boryl [(PDAB)Li(THF)(2)]; this work establishes that main group reagents can achieve selective borylations of fused polycyclic aromatics under mild conditions in good yields.