title: Directing group assisted nucleophilic substitution of propargylic alcohols via o-quinone methide intermediates: Brønsted acid catalyzed, highly enantio- and diastereoselective synthesis of 7-alkynyl-12a-acetamido-substituted benzoxanthenes.
abstract: BINOL-based, chiral phosphoric acids catalyze the substitution of 1-(o-hydroxyphenyl)propargylic alcohols with enamides to furnish 7-alkynyl-12a-acetamido-substituted benzo[c]xanthenes and related heterocycles in a one-pot operation with excellent diastereo- and enantioselectivity. Ambient reaction temperature, operationally simple reaction conditions, low catalyst loading, high yields, and excellent stereocontrol are attractive features of this process and make it a highly practical and versatile transformation.
authors.affiliation: Institute of Organic Chemistry, University of Leipzig , Johannisallee 29, D-04103 Leipzig, Germany.
authors.forename: Satyajit
authors.initials: S
authors.lastname: Saha
authors.forename: Christoph
authors.initials: C
authors.lastname: Schneider