Conformational Study of N,N'-Diacyl Bispidines and Dioxo Bis-bispidines: Planar Chirality and Molecular Switching.

N,N'-Diacyl bispidines exhibit chirality in the absence of a chiral center and axis. Conformational analysis indicates planar chirality in the molecular structure as a result of open-ended chiral planes, which has been confirmed by X-ray diffraction studies. Substantial chiral-achiral molecular switching is observed in di(haloacetyl) bispidines upon changing the solvent polarity. Tethering the chiral planes with a bispidine linker alters the planar chirality significantly and renders the resulting bis-bispidine macrocycles achiral.