title: Rhodium-Catalyzed Enantioselective Silylation of Cyclopropyl C-H Bonds.
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.
authors.affiliation: Department of Chemistry, University of California, Berkeley, CA, 94720, USA.
authors.forename: Taegyo
authors.initials: T
authors.lastname: Lee
authors.affiliation: Department of Chemistry, University of California, Berkeley, CA, 94720, USA. jhartwig@berkeley.edu.
authors.forename: John F
authors.initials: JF
authors.lastname: Hartwig
mesh_terms: D002244:Carbon / Q000737:chemistry; D002384:Catalysis; D003521:Cyclopropanes / Q000737:chemistry*; D006859:Hydrogen / Q000737:chemistry; D012238:Rhodium / Q000737:chemistry*; D012821:Silanes / Q000737:chemistry*; D013237:Stereoisomerism
chemical_list: D003521:Cyclopropanes; D012821:Silanes; D002244:Carbon; D006859:Hydrogen; C030797:cyclopropane; D012238:Rhodium
keywords: C−H activation; asymmetric catalysis; cyclopropanes; rhodium; silylation