NITROXIDES .73. ELECTRON-SPIN RESONANCE STUDY OF CHIRAL RECOGNITION BY CYCLODEXTRIN

The spectral changes associated with the complexation of biradical 1 (dispiro[(2, 2, 6, 6-tetramethypiperidine-l-oxyl)- 4, 4ʹ-(oxazolidine-3ʹ-oxyl)-2ʹ,1ʺ-(3ʺ-methylcyclohexane)] with β-cyclodextrin have been used to show the difference of complexation of (+)- and (-)-fenchone by β-cyclodextrin: in water/dimethyl sulfoxide (I/I by volume) and in the presence of β- cyclodextrin, biradical I shows a spectrum in which four peaks can be attributed to the biradical included in cyclodextrin. The intensity of these peaks decreases when fenchone is added, more with (+)-fenchone than with (-)-fenchone. This shows that (+)-fenchone is more complexed by β-cyclodextrin than (-)-fenchone. A precipitation experiment is in agreement with the spectroscopic result.© 1979, American Chemical Society. All rights reserved.