The scope of catalytic asymmetric hydroboration/oxidation with rhodium complexes of 1,1 '-(2-diarylphosphino-1-naphthyl)isoquinolines

Preformed cationic Rh complexes of the title ligands are effective for the asymmetric hydroboration/oxidation of vinylarenes at ambient temperature. T hese vinylarenes may carry E- or Z-beta substituents but not a substituents . Enantiomer excesses of up to 97% can be obtained in the most favourable c ases. The enantioselectivity is moderately sensitive to the structure of th e ligand: the difurylphosphino ligand gave superior results for electron-po or styrenes and the diphenylphosphino ligand the best results for electron- rich reactants. Mechanistic aspects are discussed.