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

The unique combination of geometric and electronic properties explains the remarkable magnitude of the Cotton effects in the circular dichroism spectra of new enantiomerically pure alleno-acetylenic macrocycles (see picture). The macrocycles (P,P,P,P)-(−)-1 (red) and (M,M,M,M)-(+)-1 (blue) were prepared in three steps starting from optically pure 1,3-di-tert-butyl-1,3-diethynylallenes.