title: Formation of optically active chromanes by catalytic asymmetric tandem oxa-Michael addition-Friedel-Crafts alkylation reactions.
abstract: A novel tandem reaction involving an oxa-Michael addition, followed by a Friedel-Crafts alkylation has been developed. This catalytic tandem reaction, which provides facile and efficient access to optically active functionalised chromanes, proceeds under the influence of bisoxazoline-based catalysts to give diastereomerically pure products in enantioselectivities up to 81% and excellent yields. The optimisation studies, the scope of the reaction, and a model that on the basis of PM3 calculations predicts the outcome of the reaction will be detailed.
authors.affiliation: Danish National Research Foundation, Center for Catalysis, Department of Chemistry, Aarhus University, DK-8000 Aarhus C, Denmark.
authors.forename: Hester L
authors.initials: HL
authors.lastname: van Lingen
authors.forename: Wei
authors.initials: W
authors.lastname: Zhuang
authors.forename: Tore
authors.initials: T
authors.lastname: Hansen
authors.forename: Floris P J T
authors.initials: FP
authors.lastname: Rutjes
authors.forename: Karl Anker
authors.initials: KA
authors.lastname: Jørgensen