1044232-97-4Relevant academic research and scientific papers
Twin triptycyl spinning tops: A simple case of molecular gearing with dynamic C2 symmetry
Nikitin, Kirill,Mueller-Bunz, Helge,Ortin, Yannick,Risse, Wilhelm,McGlinchey, Michael J.
, p. 3079 - 3084 (2008)
Lithiation and subsequent oxidation of the recently described prototype molecular paddlewheel 9-(2-indenyl)triptycene (1) leads to the racemic dimer 2,2′-bis(9-triptycyl)-1,1′-biindenyl (4). In the solid state this very congested molecule adopts a conformation in which the two triptycenyl paddlewheel fragments are attached to the C2-symmetric biindenyl core. However, the orientation of the triptycene blades, dictated by their size and shape, is gear-like and breaks the nascent C2-symmetry of the whole molecule. Nevertheless, effective C2-symmetry is restored in solution when the triptycene paddlewheels, although apparently tightly interlocked, undergo rapid contra-rotation on the NMR time-scale. The analogous reaction of (2-phenylindenyl)lithium (6), likewise yields racemic (RR/SS) 2,2′-diphenyl-1,1′-biindenyl(7). Interestingly, although the treatment of 6 with a CuII salt leads to both rac-7 and its diastereomer meso-7, the reaction of 6 and 2-phenylindenyl bromide furnishes selectively rac-7. Overall, these data suggest that the oxidative dimerisation to yield racemic products occurs through a nucleophilic substitution mechanism.
