title: Ligand scaffold optimization of a supramolecular hydrogenation catalyst: Analyzing the influence of key structural subunits on reactivity and selectivity.
abstract: Results are reported for the catalytic asymmetric hydrogenation of two prototypical substrates with a series of more than 150 closely related supramolecular catalysts differing in only their ligand/catalyst scaffold. These modular catalysts are constructed from four subunits and vary widely in their reactivity (no reaction to quantitative yield) and enantioselectivity (racemic to 96% ee). Analysis of the ligand/catalyst scaffold optimization data reveals how each subunit contributes to the effectiveness of the modular supramolecular catalyst. The results suggest that a balance between key elements of rigidity and flexibility is required for the successful catalysts and, moreover, that this balance is required to enable effective fine-tuning via catalyst scaffold optimization.
authors.affiliation: Department of Chemistry, University of Nebraska-Lincoln, Lincoln, Nebraska 68588-0304, USA.
authors.forename: Nathan C
authors.initials: NC
authors.lastname: Thacker
authors.forename: Shin A
authors.initials: SA
authors.lastname: Moteki
authors.forename: James M
authors.initials: JM
authors.lastname: Takacs
keywords: asymmetric catalysis; asymmetric hydrogenation; rhodium-catalyzed; self-assembled ligands; self-assembly; supramolecular catalysis