Self-Assembly of Bidentate Ligands for Combinatorial Homogeneous Catalysis Based on an A—T Base Pair Model

ChemInform ◽  
2006 ◽  
Vol 37 (31) ◽  
Author(s):  
Bernhard Breit ◽  
Wolfgang Seiche
Keyword(s):  
Homogeneous Catalysis ◽  
Base Pair ◽  
Self Assembly ◽  
Bidentate Ligands ◽  
Pair Model

Self-assembly of bidentate ligands for combinatorial homogeneous catalysis based on an A-T base pair model

2006 ◽  
Vol 78 (2) ◽  
pp. 249-256 ◽  
Author(s):  
Bernhard Breit ◽  
Wolfgang Seiche
Keyword(s):  
Hydrogen Bonding ◽  
Metal Complex ◽  
Base Pair ◽  
Self Assembly ◽  
Bidentate Ligands ◽  
Metal Complex Catalysis ◽  
System A ◽  
Pair Model ◽  
Excellent Activity ◽  
Monodentate Ligands

A new concept for generation of chelating ligand libraries for homogeneous metal complex catalysis based on self-assembly is presented. Thus, self-assembly of structurally simple monodentate ligands in order to give structurally more complex bidentate ligands is achieved employing hydrogen bonding. Based on this concept and on the 2-pyridone/hydroxypyridine tautomeric system, a new rhodium catalyst was identified which operated with excellent activity and regioselectivity upon hydroformylation of terminal alkenes. In order to generate defined unsymmetrical heterodimeric ligands, an A-T base pair analog-the aminopyridine/isoquinolone system-was developed which allows for complementary hydrogen bonding. Based on this platform, a 4 x 4 phosphine ligand library was screened in the course of the rhodium-catalyzed hydroformylation of 1-octene. A catalyst operating with outstanding activity and regioselectivity in favor of the linear aldehyde was discovered.

scholarly journals Self-Assembly of Bidentate Ligands for Combinatorial Homogeneous Catalysis: Asymmetric Rhodium-Catalyzed Hydrogenation.

ChemInform ◽  
2006 ◽  
Vol 37 (31) ◽  
Author(s):  
Martine Weis ◽  
Christoph Waloch ◽  
Wolfgang Seiche ◽  
Bernhard Breit
Keyword(s):  
Homogeneous Catalysis ◽  
Self Assembly ◽  
Bidentate Ligands

Self-Assembly of Bidentate Ligands for Combinatorial Homogeneous Catalysis:  Asymmetric Rhodium-Catalyzed Hydrogenation

2006 ◽  
Vol 128 (13) ◽  
pp. 4188-4189 ◽  
Author(s):  
Martine Weis ◽  
Christoph Waloch ◽  
Wolfgang Seiche ◽  
Bernhard Breit
Keyword(s):  
Homogeneous Catalysis ◽  
Self Assembly ◽  
Bidentate Ligands

scholarly journals Rhodium-catalyzed asymmetric hydrogenation using self-assembled chiral bidentate ligands

2006 ◽  
Vol 78 (2) ◽  
pp. 501-509 ◽  
Author(s):  
James M. Takacs ◽  
Kittichai Chaiseeda ◽  
Shin A. Moteki ◽  
D. Sahadeva Reddy ◽  
Di Wu ◽  
...  
Keyword(s):  
Self Assembly ◽  
Metal Forming ◽  
Asymmetric Hydrogenation ◽  
Catalyst System ◽  
Asymmetric Induction ◽  
Bidentate Ligands ◽  
Catalytic Metal ◽  
Preliminary Study ◽  
Self Assembled ◽  
Heteroleptic Complex

The chirality-directed self-assembly of bifunctional subunits around a structural metal - typically, zinc(II) - is used to form a heteroleptic complex in which a second set of ligating groups are suitably disposed to bind a second metal, forming a heterobimetallic catalyst system. We find that subtle changes in the structural backbone (i.e., ligand scaffold) of such chiral bidentate self-assembled ligands (SALs) can be used to manipulate the ligand topography and chiral environment around catalytic metal; thus, the scaffold can be optimized to maximize asymmetric induction. Using this combinatorial strategy for ligand synthesis, a preliminary study was carried out in which a library of 110 SALs was evaluated in the rhodium-catalyzed asymmetric hydrogenation of a simple N-acyl enamide. The level of enantioselectivity obtained varies from near racemic to greater than 80 % ee as a function of the ligand scaffold, with the possibility of further improvement yet to be explored.

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