Asymmetric hydrogenation of imines with chiral alkene-derived boron Lewis acids
作者:Xiaoqin Liu、Ting Liu、Wei Meng、Haifeng Du
DOI:10.1039/c8ob02446d
日期:——
With the aim of developing easily accessible chiral Lewis acids for asymmetrichydrogenation, a variety of binaphthyl-based chiral alkenes were prepared in one step from the corresponding diols. Using the in situ generated chiral boron Lewis acids through the hydroboration of chiral alkenes with Piers’ borane, metal-free asymmetrichydrogenations of imines were realized to furnish the desired amine
A Reusable Co Catalyst for the Selective Hydrogenation of Functionalized Nitroarenes and the Direct Synthesis of Imines and Benzimidazoles from Nitroarenes and Aldehydes
作者:Tobias Schwob、Rhett Kempe
DOI:10.1002/anie.201608321
日期:2016.11.21
presence of highly hydrogenation‐sensitive functional groups, as well as the direct synthesis of imines from nitroarenes and aldehydes or ketones in the presence of such substituents. Furthermore, we introduce the first base‐metal‐mediated direct synthesis of benzimidazolesfrom nitroarenes and aldehydes. Functional groups that are easy to hydrogenate are again well tolerated.
The Ir-catalyzed asymmetric hydrogenation of acyclic aromatic N-aryl imines with Josiphos-type binaphane ligands has been described. Under the optimized conditions, a wide range of imines were hydrogenated to afford the corresponding chiral amines in high yields (up to 94%) and good to excellent enantioselectivities (up to >99% ee). The synthetic utility of the present protocol has been demonstrated