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

Stereocontrol of cyclophane-type planar chirality was achieved by spontaneo us 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 r ope-skipping isomerization with precipitation of the solid (S.3'S)-1a-f, co mpleting the disequilibriation to (S,3'S)-1a-f with up to 99% de. (C) 2001 Elsevier Science Ltd. All rights reserved.