Abstract
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.
Conference
IUPAC International Symposium on Organometallic Chemistry Directed Towards Organic Synthesis (OMCOS-13), International Symposium on Organometallic Chemistry Directed Toward Organic Synthesis, OMCOS, Organometallic Chemistry Directed Toward Organic Synthesis, 13th, Geneva, Switzerland, 2005-07-17–2005-07-21
© 2013 Walter de Gruyter GmbH, Berlin/Boston
