Stereospecific Intramolecular Reductive Cross-Electrophile Coupling Reactions for Cyclopropane Synthesis

The stereo­specific reductive cross-electro­phile coupling reaction of 2-aryl-4-chloro­tetra­hydro­pyrans to afford disubstituted cyclo­propanes is reported. This ring contraction presents surprises with respect to the stereo­chemical outcome of reaction of the alkyl halide moiety. While cross-coupling and reductive cross-electro­phile coupling reactions of alkyl halides are typically stereo­ablative, using a chiral catalyst to set the stereo­center, this transformation proceeds with high stereo­chemical fidelity at the alkyl halide and ether bearing stereo­genic centers. This approach provides straightforward access to highly substituted cyclopropanes in two steps from commercially available aldehydes.