Circular Dichroism Studies on Three Isomeric Dimethylbenzo-15-crown-5 Ethers and Some of Their Complexes

Article abstract of DOI:10.1021/jo00160a018

With ethyl lactate as an optically active precursor and with employment of Williamson reactions, three isomeric and axially symmetric dimethylbenzo-15-crown-5 ethers were prepared and characterized: (5R,15R)-5,15-dimethyl-5,6,8,9,11,12,14,15-octahydrobenzo-1,4,7,10,13-pentaoxacyclopentadecin and the (6S,14S)-6,14-dimethyl and (8S,12S)-8,12-dimethyl isomers, termed the α, β, and γ isomers, respectively.The circular dichroism spectra of the ethers and their complexes with Na⁺ in CH3OH have been determined and interpreted in terms of the gross overall orientationof the macrocycle in relation to the aromatic ring.The behavior of the γ-isomer with Ba²⁺ and with low ratios of K⁺ suggests dominance of 2:1 (sandwich) complexes.