Asymmetric hydrogenation of aromatic carbocycles

The dearomative reduction of (hetero)aromatic compounds represents one of straightforward and attractive transformations for the construction of chiral cyclic compounds, which contain important structural motifs in a wide range of scientific disciplines. Stereoselective hydrogenation of carbocyclic arenes requires higher reaction temperature than that of heteroarenes because the benzene ring is highly stabilized with its inherent aromaticity. Considering the kinetic aspects of enantioselective transformations, high reaction temperature is generally unfavorable. To achieve high stereoselectivity, therefore, carefully and precisely designed chiral auxiliary or catalyst is particularly desirable. Herein, we will summarize two distinct approaches for the asymmetric hydrogenation of aromatic carbocycles: (1) through combinational use of chiral auxiliary and heterogeneous catalysis, (2) with chiral homogeneous metal complex as the catalyst.