Cu-Catalyzed Hydroboration of Benzylidenecyclopropanes: Reaction Optimization, (Hetero)Aryl Scope, and Origins of Pathway Selectivity Jose M. Medina Taeho Kang Tuğçe G. Erbay Huiling Shao Gary M. Gallego Shouliang Yang Michelle Tran-Dubé Paul F. Richardson Joseph Derosa Ryan T. Helsel Ryan L. Patman Fen Wang Christopher P. Ashcroft John F. Braganza Indrawan McAlpine Peng Liu Keary M. Engle 10.1021/acscatal.9b03557.s002 https://acs.figshare.com/articles/dataset/Cu-Catalyzed_Hydroboration_of_Benzylidenecyclopropanes_Reaction_Optimization_Hetero_Aryl_Scope_and_Origins_of_Pathway_Selectivity/10274801 The copper-catalyzed hydroboration of benzylidenecyclopropanes, conveniently accessed in one step from readily available benzaldehydes, is reported. Under otherwise identical reaction conditions, two distinct phosphine ligands grant access to different products by either suppressing or promoting the cyclopropane opening via β-carbon elimination. Computational studies provide insight into how the rigidity and steric environment of these different bis-phosphine ligands influence the relative activation energies of β-carbon elimination versus protodecupration from the key benzylcopper intermediate. The method tolerates a wide variety of heterocycles prevalent in clinical and preclinical drug development, giving access to valuable synthetic intermediates. The versatility of the tertiary cyclopropylboronic ester products is demonstrated through several derivatization reactions. 2019-11-08 14:43:51 phosphine ligands grant access reaction conditions copper-catalyzed hydroboration Hetero activation energies Scope benzylidenecyclopropane rigidity cyclopropane opening Pathway Selectivity cyclopropylboronic ester products steric environment versatility intermediate benzylcopper β- carbon elimination benzaldehyde Cu-Catalyzed Hydroboration insight Origins protodecupration derivatization reactions bis-phosphine ligands influence heterocycle Computational studies variety method Reaction Optimization drug development Benzylidenecyclopropane