title: Stereodivergent organocatalytic intramolecular Michael addition/lactonization for the asymmetric synthesis of substituted dihydrobenzofurans and tetrahydrofurans.
abstract: A stereodivergent asymmetric Lewis base catalyzed Michael addition/lactonization of enone acids into substituted dihydrobenzofuran and tetrahydrofuran derivatives is reported. Commercially available (S)-(-)-tetramisole hydrochloride gives products with high syn diastereoselectivity in excellent enantioselectivity (up to 99:1 d.r.syn/anti , 99 % eesyn ), whereas using a cinchona alkaloid derived catalyst gives the corresponding anti-diastereoisomers as the major product (up to 10:90 d.r.syn/anti , 99 % eeanti ).
authors.affiliation: EaStCHEM, School of Chemistry, University of St. Andrews, North Haugh, St. Andrews, KY16 9ST (UK).
authors.forename: Dorine
authors.initials: D
authors.lastname: Belmessieri
authors.forename: Alix
authors.initials: A
authors.lastname: de la Houpliere
authors.forename: Ewen D D
authors.initials: ED
authors.lastname: Calder
authors.forename: James E
authors.initials: JE
authors.lastname: Taylor
authors.forename: Andrew D
authors.initials: AD
authors.lastname: Smith
mesh_terms: D001572:Benzofurans / Q000138:chemical synthesis* / Q000737:chemistry; D002384:Catalysis; D005663:Furans / Q000138:chemical synthesis* / Q000737:chemistry; D013237:Stereoisomerism
chemical_list: D001572:Benzofurans; D005663:Furans
keywords: Michael addition; asymmetric catalysis; cinchona alkaloid; isothiourea; organocatalysis; oxygen heterocycles; stereodivergent