posted on 2021-06-21, 13:03authored byChen-Fei Liu, Xiaohua Luo, Hongyu Wang, Ming Joo Koh
Alkene hydrocarbofunctionalization
represents one of the most important
classes of chemical transformations, but related branched-selective
examples with unactivated olefins are scarce. Here, we report that
catalytic amounts of a dimeric Ni(I) complex and an exogenous alkoxide
base promote Markovnikov-selective hydroarylation(alkenylation) of
unactivated and activated olefins using organo bromides or triflates
derived from widely available phenols and ketones. Products bearing
aryl- and alkenyl-substituted tertiary and quaternary centers could
be isolated in up to 95% yield and >99:1 regioisomeric ratios.
Contrary
to previous dual-catalytic methods that rely on metal-hydride atom
transfer (MHAT) to the olefin prior to carbofunctionalization with
a cocatalyst, our mechanistic evidence points toward a nonradical
reaction pathway that begins with site-selective carbonickelation
across the CC bond followed by hydride transfer using alkoxide
as the hydride source. Utility of the single-catalyst protocol is
highlighted through the synthesis of medicinally relevant scaffolds.