title: Asymmetric catalytic cycloetherification mediated by bifunctional organocatalysts.
abstract: Oxacyclic structures such as tetrahydrofuran (THF) rings are commonly found in many bioactive compounds, and this has led to several efforts toward their stereoselective syntheses. However, the process of catalytic asymmetric cycloetherification for their straightforward synthesis has remained a challenge. In this study, we demonstrate a novel asymmetric synthesis method for THF via the catalytic cycloetherification of ε-hydroxy-α,β-unsaturated ketones mediated by cinchona-alkaloid-thiourea-based bifunctional organocatalysts. This catalytic process represents a highly practical cycloetherification method that provides excellent enantioselectivities, even with low catalyst loadings at ambient temperature.
authors.affiliation: Department of Material Chemistry, Graduate School of Engineering, Kyoto University, Kyotodaigaku-Katsura, Nishikyo, Kyoto 615-8510, Japan.
authors.forename: Keisuke
authors.initials: K
authors.lastname: Asano
authors.forename: Seijiro
authors.initials: S
authors.lastname: Matsubara
mesh_terms: D002384:Catalysis; D002930:Cinchona Alkaloids / Q000737:chemistry; D003500:Cyclization; D004987:Ethers / Q000737:chemistry*; D005663:Furans / Q000138:chemical synthesis* / Q000737:chemistry; D007659:Ketones / Q000737:chemistry*; D015394:Molecular Structure; D013890:Thiourea / Q000737:chemistry
chemical_list: D002930:Cinchona Alkaloids; D004987:Ethers; D005663:Furans; D007659:Ketones; C018674:tetrahydrofuran; D013890:Thiourea