Cyclopropanes are both valuable building blocks in synthetic chemistry and important
functional moieties existing in natural products and biologically active molecules.
The Simmons-Smith cyclopropanation has become a very useful and reliable method for
the synthesis of cyclopropanes from olefins. Aiming at the development of tunable
and highly reactive zinc carbenoids, Shi and coworkers put forward an effective strategy
for the generation of zinc carbenoids RXZnCH2I by reacting RXH with an appropriate
organozinc reagent, which allows tuning the reactivity of RXZnCH2I reagents simply
by changing the modifier RXH. This type of carbenoid reagents was known as Shi carbenoid
or reagent and found to be highly effective for each type of olefins, which attracts
intensive attention and results in numerous successful applications in the synthesis
of complex molecules as well as important cyclopropane building blocks. Significantly,
the asymmetric Simmons-Smith cyclopropanation of unfunctionalized olefines has also
been achieved using a chiral modifier.
