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
ChemInform ◽  
2006 ◽  
Vol 37 (31) ◽  
Author(s):  
Martine Weis ◽  
Christoph Waloch ◽  
Wolfgang Seiche ◽  
Bernhard Breit

2006 ◽  
Vol 78 (2) ◽  
pp. 501-509 ◽  
Author(s):  
James M. Takacs ◽  
Kittichai Chaiseeda ◽  
Shin A. Moteki ◽  
D. Sahadeva Reddy ◽  
Di Wu ◽  
...  

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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