Catalytic Asymmetric Hydrogenation of Heteroarenes and Arenes

Abstract

A trans-chelating chiral bisphosphine, PhTRAP, allows the ruthenium-catalyzed hydrogenation of various azoles to proceed with high enantioselectivity. The PhTRAP-ruthenium catalyst transformed indoles, pyrroles, imidazoles, and oxazoles into the corresponding chiral heterocycles. Naphthalenes are also reduced with hydrogen by the chiral ruthenium catalyst, exclusively giving tetralins. Some 2-alkoxytetralins were obtained with over 90% ee from the catalytic asymmetric hydrogenation of the corresponding substituted naphthalenes.