Synthesis of 2-(lutidinyl)organoboranes and their reactivities against dihydrogen and pinacol borane

Two 2,4,6-tris(trifluoromethyl)phenyl-substituted 2-(lutidinyl)organoboranes (5a and 5b) were prepared. These complexes can function as intramolecular vicinal B/N frustrated Lewis pairs to heterolytically activate dihydrogen. When these complexes were treated with HBpin, two different reaction pathways took place. Whereas the reaction between 5a and HBpin affords a formal ligand-redistribution product, the reaction of 5b with HBpin leads to a dearomative dehydroborylation product.