Rhodium-Catalyzed Enantioselective Silylation of Cyclopropyl C-H Bonds
1Department of Chemistry, University of California, Berkeley, CA, 94720, USA.
Abstract:
Hydrosilyl ethers, generated in situ by the dehydrogenative silylation of cyclopropylmethanols with diethylsilane, undergo asymmetric, intramolecular silylation of cyclopropyl C-H bonds in high yields and with high enantiomeric excesses in the presence of a rhodium catalyst derived from a rhodium precursor and the bisphosphine (S)-DTBM-SEGPHOS. The resulting enantioenriched oxasilolanes are suitable substrates for the Tamao-Fleming oxidation to form cyclopropanols with conservation of the ee value from the C-H silylation. Preliminary mechanistic data suggest that C-H cleavage is likely to be the turnover-limiting and enantioselectivity-determining step.
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