The Rotatory Dispersion and Stereochemistry of Organic Compounds. XV. Nitrophenyl Glycosides

Abstract

Abstract It has been reported that some ortho-nitrophenyl glycosides exhibit anomalous optical rotation (Montgomery et al., J. Am. Chem. Soc., 64, 690 (1942)). To investigate this anomalous effect of the ortho-nitro group the authors have observed the RD spectra on twenty-five derivatives of o-nitrophenyl, p-nitrophenyl and phenyl glycosides. Every o-nitrophenyl derivative (I, IV, VII, XI, XIV, XVII and XX) exhibited a positive Cotton effect near 340 mμ. Furthermore, in order to inquire into this anomaly the authors have observed the CD and UV spectra of these compounds. It follows that the o-nitro group is twisted from the benzene ring plane, and that the o-nitrophenyl group itself becomes an optical active chromophore, so that the Cotton effects near 340 mμ are caused by the n→π* transition of the nitro group. Therefore, the anomaly of o-nitrophenyl glycosides in the [α]D values is concluded to be affected by the strong Cotton effect near 340 mμ.