Chiral dithia[n]paracyclophanes - Synthesis, crystal structure, and chiroptical properties

The synthesis of the shortly bridged dithia[n]paracyclophanes (n=7, 8) 1-5 was achieved by the cesium-assisted high-dilution cyclization for the first time. A chiral molecular structure is induced by the pattern of the two methyl substituents. A structure with CI symmetry for the dithia[7]paracyclophane 1 is proven by X-ray structure analysis and by low-temperature NMR experiments. The benzene ring is strongly deformed to a boat-shaped conformation. Enantiomeric separation of the cyclophanes 2-5 and the circular dichrograms of the enantiomers are discussed. Copyright (C) 1996 Elsevier Science Ltd