Chiral arylene-ethynylene macrocycles (AEMs) were synthesized via alkyne metathesis. The effect of chirality on the product distribution was investigated via depolymerization of enantiomeric BINOL-based polymers. Complete selectivity for the homochiral dimers is observed from metathesis of an alternating racemic polymer or of a mixture of enantiomeric polymers. No mixing is observed between the enantiopure dimers. Chiral dynamic libraries are often complex due to the presence of many diastereomers. Typically, a template is required in chiral dynamic libraries to perturb the equilibrium in favor of enantiomerically enriched macrocyclic targets. However, in this system, the homochiral BINOL-based dimers are the thermodynamic products formed from a racemic library via a non-chiral alkyne metathesis catalyst. In addition to discovering a unique dynamic thermodynamic resolution of two enantiopure AEMs, this also demonstrates the first thermodynamically-controlled synthesis of chiral AEMs.

Dynamic deracemization of BINOL-based arylene-ethynylene macrocycles

246th National Meeting (2013)

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