Redox-Active Esters in Fe-Catalyzed C–C Coupling

Cross-couplings
of alkyl halides and organometallic species based
on single electron transfer using Ni and Fe catalyst systems have
been studied extensively, and separately, for decades. Here we demonstrate
the first couplings of redox-active esters (both isolated and derived in situ from carboxylic acids) with organozinc and organomagnesium
species using an Fe-based catalyst system originally developed for
alkyl halides. This work is placed in context by showing a direct
comparison with a Ni catalyst for >40 examples spanning a range
of
primary, secondary, and tertiary substrates. This new C–C coupling
is scalable and sustainable, and it exhibits a number of clear advantages
in several cases over its Ni-based counterpart.