Site‐Fixed Hydroboration of Terminal and Internal Alkenes using BX<sub>3</sub>/<sup><i>i</i></sup>Pr<sub>2</sub>NEt**
Sida Li, Chenyang Hu, Xin Cui, Jiong Zhang, Liu Leo Liu, Lipeng Wu
Abstract
Abstract An unprecedented and general hydroboration of alkenes with BX 3 (X=Br, Cl) as the boration reagent in the presence of i Pr 2 NEt is reported. The addition of i Pr 2 NEt not only suppresses alkene polymerization and haloboration side reactions but also provides an “H” source for hydroboration. More importantly, the site‐fixed installation of a boryl group at the original position of the internal double bond is readily achieved in contrast to conventional transition‐metal‐catalyzed hydroboration processes. Further application to the synthesis of 1, n ‐diborylalkanes ( n =3–10) is also demonstrated. Preliminary mechanistic studies reveal a major reaction pathway that involves radical species and operates through a frustrated Lewis pair type single‐electron‐transfer mechanism.