The Infrared Absorption Spectra of the Steroid Sapogenins

Abstract

Vol. 75 0.86 g. (0.01 mole) of vinyl ether, 0.098 g. (0.001 mole) of potassium acetate and 0.5 ml. of glacial acetic acid (0.01 mole) dissolved in 100 ml. of 80% dioxane. The solutions were sealed in Cams tubes and heated on a steam-bath for 64.5 hours. Distillation of the contents of one of the tubes into a 25-ml. portion of 2,4-dinitrophenylhydrazine reagent yielded no precipitate even on standing. Dilution of this same solution with water did yield a small amount of precipitate (less than 0.1 g.) melting point 174-177°, mixed m.p. with isobutyraldehyde 2,4-dmitrophenylhydrazone, 175-180°. The contents of the second tube were distilled into freshly prepared Fehling solution. No precipitate developed.Rate Measurements.-The rate measurements in anhydrous acetic acid and in "80%" dioxane were carried out as in previous work.3•5 The "80%" dioxane was the same solvent described previously.3 Good first order kinetics were observed.

Complete ¹H and 13C NMR assignments of isojuripidine from Solanum asterophorum Mart.

“…Compound 1 was obtained as an amorphous powder and gave a positive Dragendorff reagent test. The spectral data were in agreement of a (25R)-spirostan steroidal type skeleton, with the IR spectrum (KBr) showing absorptions at 3409 cm -1 (ν max N-H and O-H), with a 25R-spirostan structure (supported by peaks at 982, 956, 920 and 899 cm -1 , intensity 920<899,) 12 and confirmed by 1 H NMR 13,14 and 13 C NMR. 15,16 As expected the 1 H NMR spectrum (Table 1) showed the signals of two methyl singlets, two methyl doublets, and a multiplet due to an oxymethine hydrogen.…”

ESI‐QqTOF‐MS/MS and APCI‐IT‐MS/MS analysis of steroid saponins from the rhizomes of Dioscorea panthaica

“…It is notable that the band B is bigger than band C in 25S type SS, while the band B is smaller than band C in 25R type SS, on the basis of which the C-25 isomers can be differentiated. 13 For the saturated SS, there is no UV absorption. If isolated double bond, carbonyl,˛,ˇ-unsaturated ketone or conjugated double bonds were present, UV absorption would occur.…”

“…However, the major disadvantage of this method is the cyclization of furostanol to spirostanol aglycone and it can yield several alternative structures to that of the original compound. In such cases, 13 C NMR spectral analysis provides a nondestructive way for the characterization of a saponin. 14 In addition, the site at which one sugar is attached to another sugar of a saponin can readily be determined by 13 C NMR spectroscopy, and this is perhaps the most significant information contained in the spectrum, which is difficult to obtain by other methods.…”

“…In such cases, 13 C NMR spectral analysis provides a nondestructive way for the characterization of a saponin. 14 In addition, the site at which one sugar is attached to another sugar of a saponin can readily be determined by 13 C NMR spectroscopy, and this is perhaps the most significant information contained in the spectrum, which is difficult to obtain by other methods. 15 For workers engaged in the study of bioactive constituents of medicinal plants, one of the most time-consuming steps is the structural elucidation of saponins, after the extraction and isolation of effective components.…”

Aza Steroids: Iii. Synthesis of 11-Aza Steroids—a Novel Class of Steroidal Sapogenin Analogues

“…When we subjected this substance t o ozonolysis we obtained in low yield, from the acidic fraction of the reaction product, a crystalline, high-melting compound which exhibited the expected properties of the desired 9,12-seco keto acid (I). The infrared spectrum indicated two bands in the carbonyl region (5.80 p, 5.93 p) and still retained the characteristic spiroketal bands (8,9), indicating that the spiroketal side chain remained unaffected under these conditions. In spite of numerous experiments, we were not able t o improve the yield in this reaction and we turned to consider another approach to this problem.…”