Browsing by Subject "MECHANICAL BOND"

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    Enhancing the selectivity of prolinamide organocatalysts using the mechanical bond in [2]rotaxanes
    (Royal Society of Chemistry, 2020-03-11) Calles, Maria; Puigcerver, Julio; Alonso, Diego A.; Alajarín, Mateo; Martinez-Cuezva, Alberto; Berná Cánovas, José; Química Orgánica
    The synthesis of a pair of switchable interlocked prolinamides and their use as organocatalysts in three different enamine-activated processes are reported. A diacylaminopyridine moiety was incorporated into the thread for directing [2]rotaxane formation further allowing the association of complementary small molecules. The rotaxane-based systems were tested as organocatalysts in asymmetric enamine-mediated processes, revealing a significantly improved catalytic ability if compared with the non-interlocked thread. The presence of an electron-withdrawing nitro group at the macrocycle helps to achieve high conversions and enantioselectivities. These systems are able to interact with N-hexylthymine as a cofactor to form supramolecular catalysts displaying a divergent catalytic behaviour. The presence or absence of the cofactor controls the chemoselectivity in competitive reactions.