Chirale 2,2′‐Polyoxaalkano‐9,9′‐spirobifluorene

Abstract

Chiral 2,2′‐polyoxaalkano‐9,9′‐spirobifluorenes From 2,2′‐diacetyl‐9,9′‐spirobifluorene (2) , twelve chiral polyethers have been prepared as potential ion‐ and enantiomer‐selective ionophores. The absolute configuration of the polyethers 15 – 17 , 19 – 22 , and 25 has been determined by chemical correlation with vespirenes [11] [29], by circular dichroism, and by X‐ray analysis. The circular dichroism of 15 – 17 , 19 and 21 depends on the size of the macrocycle and indicates that the fluorene chromophores of 19 and 21 with 13‐ and 16‐membered rings respectively deviate considerably from orthogonality.