Enantiomerically pure substances with the capacity to simultaneously activate two reagents towards one another, offer numerous opportunities for the discovery of powerful, asymmetric bond forming reactions.
When a compound possesses a combination of Lewis basic and Lewis acidic sites, has a well-defined chiral pocket constructed around a fairly rigid skeleton and appropriate distances between the two activating groups, the templating of a pro-nucleophile (NuH) and an electrophile via a ternary complex can lead to excellent levels of enantio- and diastereo-control in efficient addition reactions at low catalyst loadings.
The synergistic cooperation of multicenters (metal/metal and metal/Lewis base) has been invoked in reactions to reactive imines, aldehydes and electron poor double bonds. However, enantioselective carbon-carbon bond forming addition reactions of NuH to unactivated alkyne and alkene systems have not, despite the synthetic power of creating new carbon-carbon bonds and quaternary stereogenic centres from such unreactive substrates.
Here we propose to introduce a number of new families of metal-containing, cooperative multifunctional catalysts derived from the privileged cinchona alkaloid family. Where this idea differs conceptually from other bi functional or multifunctional catalyst systems is that our ligand canopy is intended to bind selectively to soft metal ions via soft ligating groups such as phosphines.
The unbound bridgehead nitrogen will retain its basic properties and the combination of strong Lewis base and soft Lewis acid held around the fairly rigid cinchona scaffold should confer new reactivity and stereocontrol over a wide range of reagents and substrattes.
Accordingly, we aim to introduce new catalysts, use them to discover new and powerful carbon-carbon and carbon-heteroatom bond forming reactions and ultimately control the arising stereochemistry in these reactions to an impressive degree.
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