Circular Dichroism Studies on Three Isomeric Dimethylbenzo-15-crown-5 Ethers and Some of Their Complexes
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: (5f?,15R)-5,15-dimethyl-5,6,8,9,ll,12,14,15-octahydrobenzo-l,4,7,10,13-pentaoxacyclopentadecinandthe (6S,14S)-6,14-dimethyl and (8S,12S)-8,12-dimethyl isomers, termed the a, 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 orientation of the macrocycle in relation to the aromatic ring. The behavior of the γ isomer with Ba + and with low ratios of K+ suggests dominance of 2:1 (sandwich) complexes. © 1983, American Chemical Society. All rights reserved.
Mack, MP; Hendrixson, RR; Palmer, RA; Ghirardelli, RG
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