Rotatory Dispersion and Stereochemistry of Organic Compounds. XVI. Carbonylphenyl Glucosides

Abstract Rotatory dispersion, circular dichroism and ultraviolet absorption of six kinds of carbonylphenyl tetraacetyl glucoside (carbonyl=o- and p-CHO, o- and p-COCH3, o- and p-COC2H5) and their deacetylation products were measured, and the optical rotatory contributions of carbonyl groups were investigated, especially with respect to the effect of the bulk and position of the substituent. This led to the conclusion that all the absorption bands due to the n→π* and π→π* transitions are optically active. Anomaly was also observed in the o-substitution products, thus making the general effect of electrophilic substituents on optical rotation definite, viz., that all the Cotton effects of the longer wavelength (due to the n→π* transition) are negative in p-carbonylphenyl β-glucosides, and in good accordance with the optical contribution of C1-configuration, but optical anomaly was invariably observed with the o-isomers which displayed positive Cotton effects. This rule in rotatory dispersion holds with the deacetylated compounds, in contrast to the deacetylated o-nitrophenyl glucosides (in this sense o-nitro group is anomalous). Some regularities were found with the Cotton effects due to the π→π* transition and the effect of the bulk of the carbonyl groups was discussed.