Practical and Asymmetric Reductive Coupling of Isoquinolines Templated by Chiral Diborons

We herein describe a chiral diboron-templated highly diastereoselective and enantioselective reductive coupling of isoquinolines that provided expedited access to a series of chiral substituted bisisoquinolines in good yields and excellent ee's under mild conditions. The method enjoys a broad substrate scope and good functional group compatibility. Mechanistic investigation suggests the reaction proceeds through a concerted [3,3]-sigmatropic rearrangement.