The stabilized iminium catalyzed (E)-polyene cyclization: trapping of non-activated terminating groups enabled by cation-pi interactions

A cyclic hydrazide catalyst bearing a pendant anthracene catalyzes the polyene cyclization of 1,5-hexadiene-2-carboxaldehydes. Bicyclic closure proceeds in substrates with non-activated terminating groups that fail to react with simple hydrazide catalysts. Computational analysis shows that stabilization through cation-pi interactions throughout the reaction sequence leads to the enhanced reactivity of the catalyst.