scholarly journals Asymmetric Hydrogenation of Dehydrodipeptides with Rhodium(I)–Chiral Diphosphinites. Selective (S,S)- and (R,R)-Product Formation by Double Asymmetric Induction

1984 ◽  
Vol 57 (3) ◽  
pp. 823-826 ◽  
Author(s):  
Masanobu Yatagai ◽  
Takamichi Yamagishi ◽  
Mitsuhiko Hida
Keyword(s):  
Asymmetric Hydrogenation ◽  
Product Formation ◽  
Asymmetric Induction

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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