title: Highly diastereoselective chelation-controlled additions to α-silyloxy ketones.
abstract: The polar Felkin-Anh, Cornforth-Evans, and Cram-chelation models predict that the addition of organometallic reagents to silyl-protected α-hydroxy ketones proceeds via a nonchelation pathway to give anti-diol addition products. This prediction has held true for the vast majority of additions reported in the literature, and few methods for chelation-controlled additions of organometallic reagents to silyl-protected α-hydroxy ketones have been introduced. Herein, we present a general and highly diastereoselective method for the addition of dialkylzincs and (E)-di-, (E)-tri-, and (Z)-disubstituted vinylzinc reagents to α-silyloxy ketones using alkyl zinc halide Lewis acids, RZnX, to give chelation-controlled products (dr ≥18:1). The compatibility of organozinc reagents with other functional groups makes this method potentially very useful in complex molecule synthesis.
authors.affiliation: P. Roy and Diana T. Vagelos Laboratories, Department of Chemistry, University of Pennsylvania, 231 South 34th Street, Philadelphia, Pennsylvania 19104-6323, USA.
authors.forename: Gretchen R
authors.initials: GR
authors.lastname: Stanton
authors.forename: Gamze
authors.initials: G
authors.lastname: Koz
authors.forename: Patrick J
authors.initials: PJ
authors.lastname: Walsh
mesh_terms: D002614:Chelating Agents / Q000737:chemistry*; D007659:Ketones / Q000737:chemistry*; D013237:Stereoisomerism
chemical_list: D002614:Chelating Agents; D007659:Ketones