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A Site-Selective Amination Catalyst Discriminates Between Nearly Identical C-H Bonds of Unsymmetrical Disubstituted Alkenes
preprintsubmitted on 29.10.2019, 18:09 and posted on 31.10.2019, 18:26 by Tomislav Rovis, Honghui Lei
C−H activation reactions enable chemists to unveil new retrosynthetic disconnections and streamline conventional synthetic approaches. A longstanding challenge in C−H activation is the inability to distinguish electronically and sterically similar C–H bonds. Although numerous synergistic combinations of transition-metal complexes and chelating directing groups have been utilized to distinguish C−H bonds, undirected regioselective C−H functionalization strategies remain elusive. Herein, we report a regioselective C−H activation/amination reaction of various unsymmetrical dialkyl-substituted alkenes. The regioselectivity of C−H activation is correlated to the electronic properties of allylic C−H bonds indicated by the corresponding 1JCH coupling constants. A linear relationship between the difference of 1JCH coupling constants of the two competing allylic C−H bonds (Δ 1JCH) and the C−H activation barriers (Δ ΔG ‡ ) has also been determined.