Planar Chirality of Imidazole‐Containing Macrocycles – Understanding and Tuning Atropisomerism

Abstract

Abstract The synthesis and characterization of imidazole‐containing macrocycles displaying planar chirality has been achieved. HLPC and NMR studies revealed the crucial role of the alicyclic chain length in determining the rate of stereoisomerisation: 15‐ and 16‐membered cyclic compounds are chiral whereas their larger‐ringed analogues equilibrate rapidly at room temperature. Computational calculations are in good agreement with experimental observations and allow us to understand the mechanism and the interactions involved in the conformational equilibrium between the two atropisomers. Separation of the two enantiomers of the 15‐membered macrocycle by semipreparative chiral HPLC allowed us to investigate the influence of chirality on its biological activity.