Double and Single Hydroboration of Nitriles Catalyzed by a Ruthenium-Bis(silyl)xanthene Complex: Application to One-Pot Synthesis of Diarylamines and N-Arylimines

A ruthenium complex bearing a bis(silyl)xanthene chelate ligand xantsil, i.e. Ru[κ ³ (Si,O,Si)-xantsil](CO)(PCyp ₃ ) (1a, Cyp = cyclopentyl), was found to catalyze both double and single hydroboration reactions of nitriles with pinacolborane (HBpin) and 9-borabicyclo[3.3.1]nonane (9-BBN) to give bis(boryl)amines 2 and N-borylimines 3, respectively, in mostly >99% yields. By combination of these reactions with subsequent palladium-catalyzed deborylative C-N coupling reactions of 2 and 3 with a 1:1 mixture of bromoarenes and KO ^t Bu, one-pot synthetic routes to tertiary N,N-diarylamines 4 and N-arylaldimines 5 from nitriles were developed.