title: Solvent-dependent divergent functions of Sc(OTf)₃ in stereoselective epoxide-opening spiroketalizations.
abstract: A stereocontrolled synthesis of benzannulated spiroketals has been developed using solvent-dependent Sc(OTf)3-mediated spirocyclizations of exo-glycal epoxides having alcohol side chains. In THF, the reaction proceeds via Lewis acid catalysis under kinetic control with inversion of configuration at the anomeric carbon. In contrast, in CH2Cl2, Brønsted acid catalysis under thermodynamic control leads to retention of configuration. The reactions accommodate a variety of aryl substituents and ring sizes and provide stereochemically diverse spiroketals.
authors.affiliation: Molecular Pharmacology & Chemistry Program, ‡Tri-Institutional PhD Program in Chemical Biology, and Tri-Institutional Research Program, Memorial Sloan Kettering Cancer Center , 1275 York Avenue, Box 422, New York, New York 10065, United States.
authors.forename: Indrajeet
authors.initials: I
authors.lastname: Sharma
authors.forename: Jacqueline M
authors.initials: JM
authors.lastname: Wurst
authors.forename: Derek S
authors.initials: DS
authors.lastname: Tan
mesh_terms: D004852:Epoxy Compounds / Q000737:chemistry*; D005663:Furans / Q000138:chemical synthesis* / Q000737:chemistry; D058116:Lewis Acids / Q000737:chemistry*; D008698:Mesylates / Q000737:chemistry*; D015394:Molecular Structure; D012538:Scandium / Q000737:chemistry*; D012997:Solvents / Q000737:chemistry*; D013141:Spiro Compounds / Q000138:chemical synthesis* / Q000737:chemistry; D013237:Stereoisomerism
chemical_list: D004852:Epoxy Compounds; D005663:Furans; D058116:Lewis Acids; D008698:Mesylates; D012997:Solvents; D013141:Spiro Compounds; C436603:scandium triflate; C520774:spiroketal; D012538:Scandium
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