This review describes the development of enantioselective methods for the ring opening of cyclopropanes. Both approaches based on the reaction of nonchiral cyclopropanes and (dynamic) kinetic resolutions and asymmetric transformations of chiral substrates are presented. The review is organized according to substrate classes, starting by the more mature field of donor−acceptor cyclopropanes. Emerging methods for enantioselective ring opening of acceptor-or donor-only cyclopropanes are then presented. The last part of the review describes the ring opening of more reactive three-membered rings substituted with unsaturations with a particular focus on vinylcyclopropanes, alkylidenecyclopropanes, and vinylidenecyclopropanes. In the last two decades, the field has grown from a proof of concept stage to a broad range of methods for accessing enantioenriched building blocks, and further extensive developments can be expected in the future.
The efficient catalytic activation of Donor-Acceptor aminocyclopropanes lacking the commonly used diester acceptor is reported here in a (3+2) dearomative annulation with indoles. Bench-stable tosyl-protected aminocyclopropyl esters were converted into...
The photosensitized p-anisaldehyde-mediated
addition
of sulfonylcyanides onto the π-system of cyclobutenes is shown
to afford highly functionalized cyclobutanes in high yields and diastereocontrol.
The homochiral cyclobutene precursors are accessible on multigram
scale in two steps through an asymmetric [2 + 2] cycloaddition/vinyl
thioether reduction sequence. The enantiopure cyclobutylnitriles can
be elaborated further through SmI2-mediated ring opening
or converted into new enantiopure cyclobutenes through base-mediated
sulfone elimination.
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