1. Second Coordination Sphere Promoted Catalysis: Organometallic Hydrogen
Bond Donors for Enantioselective Organic Transformations
First time description of the development of new chiral-at-metal ruthenium based
organometallic hydrogen bond donors derived from 2-guanidinobenzimidazole (GBI) and their
application in second coordination sphere promoted catalysis (SCSPC). Unlike most transition
metal catalyzed reactions, there is no direct interaction of the substrate with the ruthenium;
rather, association involves hydrogen bonding derived from NH groups which are remote from
the metal center (Figure 1).
The hydrogen bonding interactions and the activation of the substrates occurs solely in
the second coordination sphere, and thereby promote the reactions (Figure 1). Thus, these
systems successfully justify the term second coordination sphere promoted catalysis.
Isolation and successful application of enantiopure ruthenium complexes in SCSPC
establishes the viability of using these transition metal complexes containing ligand based NH
hydrogen bond donors to catalyze enantioselective organic transformations in high yields and
enantioselectivities.