Iron-Catalyzed Tunable and Site-Selective Olefin Transposition

The catalytic isomerization of C–C
double bonds is an indispensable
chemical transformation used to deliver higher-value analogues and
has important utility in the chemical industry. Notwithstanding the
advances reported in this field, there is compelling demand for a
general catalytic solution that enables precise control of the CC
bond migration position, in both cyclic and acyclic systems, to furnish
disubstituted and trisubstituted alkenes. Here, we show that catalytic
amounts of an appropriate earth-abundant iron-based complex, a base
and a boryl compound, promote efficient and controllable alkene transposition.
Mechanistic investigations reveal that these processes likely involve
in situ formation of an iron-hydride species which promotes olefin
isomerization through sequential olefin insertion/β-hydride
elimination. Through this strategy, regiodivergent access to different
products from one substrate can be facilitated, isomeric olefin mixtures
commonly found in petroleum-derived feedstock can be transformed to
a single alkene product, and unsaturated moieties embedded within
linear and heterocyclic biologically active entities can be obtained.