1. Click-Connected Scaffold Construction: A Versatile Route for Catalyst Scaffold Optimization
After investigating a series of Click-Connected Scaffolds, the spectroscopic and analytical data suggest the 16-membered P,P-macrocyclic Rh(I) chelate is shown to the left is relevant in the efficient asymmetric hydrogenation catalyzed by this complex. However, computational studies indicate the complex should be very quite strained. Further structural to resolve the discrepancy are in progress.
Bifunctional catalysts exploiting dual activation must position two groups to independently activate the substrate and reagent. Click-Connected Scaffold Construction affords the opportunity to vary the shape of the chiral substrate/reagent pocket and thereby control the reactivity and selectivity of the catalyst. While the first generation catalysts shown above achieve only modest levels of enantioselectivity, the preliminary data, particularly the wide variation in reaction rate as a function of catalyst scaffold, indicate that click-connected scaffolds can be used to develop effective organocatalysts exploiting dual activation in the oxy-Michael reaction.