title: Ortho-quinone methides as reactive intermediates in asymmetric brønsted Acid catalyzed cycloadditions with unactivated alkenes by exclusive activation of the electrophile.
abstract: An efficient method for the highly enantioselective synthesis of chiral chromanes bearing multiple stereogenic centers was developed. A chiral BINOL-based N-triflylphosphoramide proved to be an effective catalyst for the in situ generation of ortho-quinone methides (o-QMs) and their subsequent cycloaddition reaction with unactivated alkenes provided chromanes with excellent diastereo- and enantioselectivity.
authors.affiliation: Institute of Organic Chemistry, RWTH Aachen, Landoltweg 1, 52074 Aachen (Germany).
authors.forename: Chien-Chi
authors.initials: CC
authors.lastname: Hsiao
authors.forename: Sadiya
authors.initials: S
authors.lastname: Raja
authors.forename: Hsuan-Hung
authors.initials: HH
authors.lastname: Liao
authors.forename: Iuliana
authors.initials: I
authors.lastname: Atodiresei
authors.forename: Magnus
authors.initials: M
authors.lastname: Rueping
keywords: chromanes; cycloaddition; homogeneous catalysis; n-triflylphosphoramide; ortho-quinone methide