An Enantiomerically Pure Alleno-Acetylenic Macrocycle: Synthesis and Rationalization of Its Outstanding Chiroptical Response

First enantiomerically pure alleno-acetylenic macrocycles were synthesized. The origin of the main CD band proposed by calcns. was found to be in accordance with the exptl. conclusion obtained from the g-factor plot. The unique combination of geometric and electronic properties explains the magnitude of the Cotton effects.