Supramolecular Protecting Groups Can Impart Prosthetic Stereoselectivity to Catalytic Systems Employing Unmodified Achiral Heterogenous Catalysts

Use of homogeneous catalysis – typically based on scarce precious metals – remains a dominant approach to afford good yields of enantiopure compounds. Combining typical strengths of heterogenous catalysts (low cost, sustainable, recyclable) with those of precious metal-mediated homogenous catalysis (amenability to design for selectivity) is desirable: several approaches have been demonstrated (chiral material surfaces, modification of surfaces with chiral auxiliaries, immobilisation of chiral catalysts), but it remains a challenge. Here we present a systems catalysis approach, with a heterogenous material providing catalytic activity, and a separate host species controlling access to the catalyst to impart ‘prosthetic’ chiral selectivity. Since this non-covalent analogue to conventional covalent protecting group strategies is modular, the same substrate/host combination may be applied to a range of catalytic surfaces. The potential of this approach to achieve effective kinetic resolution is demonstrated in stereoselective synthesis of the drug (R)-cinacalcet.