A site-selective amination catalyst discriminates between nearly identical C-H bonds of unsymmetrical disubstituted
1Department of Chemistry, Columbia University, New York, NY, USA.
Abstract:
C-H activation reactions enable chemists to unveil new retrosynthetic disconnections and streamline conventional synthetic approaches. A long-standing 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. Here 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 in the 1JCH coupling constants of the two competing allylic C-H bonds (Δ1JCH) and the C-H activation barriers (ΔΔG‡) has also been determined.
Related Concept Videos
02:17Reduction of Alkenes: Asymmetric Catalytic Hydrogenation
The metal catalyst used can be either heterogeneous or homogeneous. When hydrogenation of an alkene generates a chiral center, a pair of enantiomeric products is expected to form. However, an enantiomeric excess of one of the products can be facilitated using an enantioselective reaction or an...
02:17Regioselectivity of Electrophilic Additions to Alkenes: Markovnikov's Rule
The hydrohalogenation of an unsymmetrical alkene can yield two haloalkane products, depending on which vinylic carbon takes up the halogen. However, one product usually predominates, where hydrogen adds to the vinylic carbon bearing the...
02:34Regioselectivity and Stereochemistry of Acid-Catalyzed Hydration
02:24Reduction of Alkynes to cis-Alkenes: Catalytic Hydrogenation
Like alkenes, alkynes can be reduced to alkanes in the presence of transition metal catalysts such as Pt, Pd, or Ni. The reaction involves two sequential syn additions of hydrogen via a cis-alkene intermediate.
02:35Regioselectivity of Electrophilic Additions-Peroxide Effect
01:11Nucleophilic Aromatic Substitution: Elimination–Addition