title: Enantiomerically Pure Tribenzotriquinacenes through Stereoselective Synthesis.
abstract: Inherently chiral acetophenones and benzaldehydes bearing the large, bowl-shaped framework of tribenzotriquinacene (TBTQ) were synthesized in enantiomerically pure form employing enzyme catalysis. Five-step sequences involving lipase CAL-B lead to the (M)-enantiomers, (+)-2-acetyl-TBTQ (M)-5 and (+)-2-formyl-TBTQ (M)-6, whereas use of lipase PS leads to the (P)-enantiomers, (-)-2-acetyl-TBTQ (P)-5 and (-)-2-formyl-TBTQ (P)-6, with at least 99% ee in each case. The absolute configuration of these rigid 3D building blocks was determined by X-ray diffraction analysis of the ketones 5 and by comparison of their chiroptical properties with those of the aldehydes 6.
authors.affiliation: Department of Chemistry, Bielefeld University, Universitätsstrasse 25, 33615 Bielefeld (Germany).
authors.forename: Wilko
authors.initials: W
authors.lastname: Greschner
authors.affiliation: Department of Chemistry, Bielefeld University, Universitätsstrasse 25, 33615 Bielefeld (Germany).
authors.forename: Beate
authors.initials: B
authors.lastname: Neumann
authors.affiliation: Department of Chemistry, Bielefeld University, Universitätsstrasse 25, 33615 Bielefeld (Germany).
authors.forename: Hans-Georg
authors.initials: HG
authors.lastname: Stammler
authors.affiliation: Department of Chemistry, Bielefeld University, Universitätsstrasse 25, 33615 Bielefeld (Germany). harald.groeger@uni-bielefeld.de.|Center for Molecular Materials (CM2), Bielefeld University, Universitätsstrasse 25, 33615 Bielefeld (Germany). harald.groeger@uni-bielefeld.de.
authors.forename: Harald
authors.initials: H
authors.lastname: Gröger
authors.affiliation: Department of Chemistry, Bielefeld University, Universitätsstrasse 25, 33615 Bielefeld (Germany). dietmar.kuck@uni-bielefeld.de.|Center for Molecular Materials (CM2), Bielefeld University, Universitätsstrasse 25, 33615 Bielefeld (Germany). dietmar.kuck@uni-bielefeld.de.
authors.forename: Dietmar
authors.initials: D
authors.lastname: Kuck
keywords: bowl-shaped molecules; enzyme catalysis; inherent chirality; lipases; tribenzotriquinacenes