Regio‐ and Enantioselective Catalytic Hydrophosphorylation of Vinylarenes

Regioselective and stereoselective hydrophosphorylation of vinylarenes 1 with pinacol H‐phosphonate 2 can be achieved with transition metal catalysts. The use of rhodium catalysts such as the Wilkinson complex leads to the anti‐Markovnikov adducts 3 as the only observable reaction products. In contrast, palladium catalysts give high selectivities for the Markovnikov adducts 4. In the presence of (R,S)‐BINAPHOS as a chiral ligand, significant enantioselectivities have been obtained for the first time in hydrophosphorylation reactions.