Metal‐Free Allylic C−H Amination of Vinylsilanes and Vinylboronates using Silicon or Boron as a Regioselectivity Switch

• Published in: Angewandte Chemie International Edition 2022-11, Vol.61 (45), p.e202210109-n/a
• Main Authors: Maloney, T. Parker, Berman, Janna L., Michael, Forrest E.
• Format: Article
• Language: English
• Subjects: allylation; Amination; Boron; Cross coupling; C−H amination; Density functional theory; Regioselectivity; Selenium; selenium catalysis; Silicon; vinylboron; vinylsilane
• ISSN: 1433-7851; 1521-3773
• DOI: 10.1002/anie.202210109

Vinylsilanes and vinylboronates are common building blocks for organic synthesis, but direct functionalization of these species without the participation of either the C=C or C−Si/B bonds is rare. Herein, we report a metal‐free allylic C−H amination reaction of these vinylmetalloid species that installs a new C−N bond without competing transmetallation or alkene addition. In this transformation, the silicon or boron substituent inverts the usual regioselectivity, directing amination to the site distal to that group. Subsequent cross‐coupling or demetallation allows access to complementary regioisomeric products. Density Functional Theory computations revealed that the observed regioselectivity is due to a subtle combination of electronic and counterintuitive steric factors that favor initial attack of selenium at the silicon‐bearing carbon atom. A metal‐free allylic C−H amination protocol allows simple vinylsilanes and vinylboronates to be selectively functionalized without competitive consumption of the reactive vinylmetalloid core structure, preserving its reactivity for future transformations such as cross‐coupling or addition reactions. The silicon/boron group directs the regioselectivity of amination to the distal side of the C=C bond, allowing access to a complementary substitution pattern.