SOME ANOMALOUS CARBONYL STRETCHING FREQUENCIES IN STEROID INFRARED SPECTRA

Abstract

Abnormal C=O and C=C stretching frequencies in the infrared spectra of Δ4-3-ketosteroids containing a 19,8-lactone bridge are discussed in relation to possible conformational structures. The C=O stretching frequencies of 1,11,17-triketo-5β-steroids and Δ2-1,11,17-triketo-5β-steroids are reported. It is noted that the anomalous C=O stretching band position previously recorded for the 11-ketone in 11,17-diketosteroids is also observed in these triketones, but no additional perturbation results from the introduction of the 1-ketone group, in spite of its proximity to the carbonyl at C11.