Highly efficient ruthenium-catalyzed asymmetric hydrogenation of N-heteroaryl vinyl ethers

A highly efficient N-heteroaryl-directed Ru-catalyzed asymmetric hydrogenation of α,α-disubstituted vinyl ethers was successfully achieved by using the commercially available ligand ( R / S )-RuCl[( p -cymene)(BINAP)]Cl. Hundred-gram scale-up of 6a was successfully completed with a consistent ee value and good yield. Various types of N-heteroaryl-substituted vinyl ethers could be hydrogenated with good to excellent enantioselectivities, providing an attractive method for the synthesis of pharmaceutically active heteroaryl compounds containing chiral ether units.