Palladium catalyzes the cyclopropanation of 2-substituted 1,1-diborylalkenes with (trimethylsilyl)diazomethane. The relative stereoselectivity is controlled via a carbene insertion sequence generating an exclusive conformation between the R and SiMe substituents. Mixed 1,1-diborylalkenes also contributed to the formation of stereoselective B, B, Si-cyclopropanes. Orthogonal activation with NaOBu gives protodeborylation preferentially on the boron moiety to the aryl group. Further oxidation gives access to polyfunctional cyclopropyl alcohols with controlled enantioselectivity when chiral boryl motifs are involved.
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| http://dx.doi.org/10.1021/acs.orglett.2c01885 | DOI Listing |
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