Interlocking the Catalyst: Thread versus Rotaxane-Mediated Enantiodivergent Michael Addition of Ketones to β-Nitrostyrene

Fumaramide threads bearing one L-prolinamide fragment have been designed as templates for promoting the efficient formation of novel Leigh's [2]rotaxanes. Both threads and rotaxanes are shown to catalyze the asymmetric addition of ketones to beta-nitrostyrene in an enantio- and diastereoselective manner. Interestingly, the enantioselective course of these processes is reversed simply by changing from thread to rotaxane as catalyst. DFT computations have allowed to rationalize the stereo-divergence shown by the interlocked and noninterlocked catalysts.