Multivalent Molecular Shuttles – Effect of Increasing the Number of Centers in Switchable Catalysts. Issue 30 (23rd September 2015) - Álvarez, Celedonio M.
Abstract: A family of three molecular shuttles based upon ammonium/triazolinium salt motifs with one, two, and three catalytic centers were prepared along with their corresponding non‐interlocked threads. The switching process for all rotaxanes was tested through an in situ procedure in solution. Furthermore, their organocatalysis of two Michale‐type reactions by iminium activation was tested to check whether the increase of the number of catalytic centers in the same shuttle is a decisive factor to improve their efficiencies compared with those of single‐active‐site organocatalytic shuttles under the same conditions. Abstract : Three molecular shuttles based upon ammonium/triazolinium salt motifs with one, two, and three catalytic centers are prepared. Their organocatalysis of two Michale‐type reactions shows that the catalysis process occurs if the amine is exposed, but this catalysis stops if the ammonium salt is covered by the crown ether.