Stereocontrol of molecular jump-rope: crystallization-induced asymmetric transformation of planar-chiral cyclophanes

Stereocontrol of cyclophane-type planar chirality was achieved by spontaneous dynamic resolution via crystallization-induced asymmetric transformation. Simply heating a 1/1 mixture of the solid and the liquid diastereoisomers of bridged nicotinamides (S,3′S)-1a–f and (R,3′S)-2a–f accelerated their rope-skipping isomerization with precipitation of the solid (S,3′S)-1a–f, completing the disequilibriation to (S,3′S)-1a–f with up to 99% de.