jo9b02154_si_001.pdf (3.67 MB)
Density Functional Theory Mechanistic Insight into the Base-Free Nickel-Catalyzed Suzuki–Miyaura Cross-Coupling of Acid Fluoride: Concerted versus Stepwise Transmetalation
journal contribution
posted on 2019-10-18, 20:13 authored by Chaoshen Zhang, Ruihua Zhao, Wasihun Menberu Dagnaw, Zheyuan Liu, Yu Lu, Zhi-Xiang WangDensity
functional theory mechanistic study has been carried out
to account for the base-free nickel-catalyzed Suzuki–Miyaura
coupling of acid fluorides (ArC(O)F) with boronic acids (Ar′B(OH)2). After oxidative addition to break the C–F bond of
acid fluoride, the resultant ArC(O)[Ni]F species undergoes transmetalation
with Ar′B(OH)2 to give ArC(O)[Ni]Ar′. Subsequently,
ArC(O)[Ni]Ar′ can either undergo decarbonylation, finally leading
to the coupling product (ArAr′), or reductive elimination to
give ketone byproduct ArC(O)Ar′. The kinetic competition between
the two pathways controls the chemoselectivity of the reaction, and
transmetalation is the rate-determining step of the coupling. Importantly,
it was found that transmetalation prefers a stepwise mechanism over
a conventional concerted one. Detailed analyses indicate that the
strong fluorophilicity of boron facilitates the base-free transmetalation
and the coordination interaction between an oxygen atom of boronic
acid and nickel gears the base-free transmetalation to undergo the
stepwise pathway. The stepwise transmetalation mechanism also involves
the nickel-catalyzed Suzuki–Miyaura coupling of aldehydes with
ketone (PhC(O)CF3) as the transmetalation promoter.