¹⁷O NMR spectroscopic investigation of steroids at natural abundance

Abstract

Natural abundance "0 NMR spectroscopic data, in toluene-d, at W"C, were obtained for dierent classes of steroids, including androstanes, estranes, pregnaoes, cholanes and cholestanes Only routine acquisition parameters were used in combination with linear prediction methods during the processing for eliminating acoustic ringing artifacts. The results are discussed in terms of stereochemical effects on the "O chemical shift of the various oxygen-containing functionalities. KEY WORDS "0 NMR Steroids Linear prediction Received

Oxygen-17 NMR spectroscopy: Basic principles and applications (Part I)

“…The spectra of polyhydroxy compounds with overlapping signals were analyzed with a curve-fitting program, which allowed the chemical shifts to be determined with an accuracy of ±0.25 ppm. The results can be very satisfactorily explained on the basis of a-, b-, and c-effects [397] ( …”

“…The c-gauche effect was found to be between À7 and À20 ppm. In this connection one should also mention the studies on cholic acid derivatives [396] and steroids selectively enriched up to 45% in 17 O [397]. The spectra of polyhydroxy compounds with overlapping signals were analyzed with a curve-fitting program, which allowed the chemical shifts to be determined with an accuracy of ±0.25 ppm.…”

Characterization of siloxane copolymers by solution 17O NMR spectroscopy

“…As no multi-pulse sequences were used to overcome the problem of acoustic ringing, the resulting baseline distortions had to be corrected after the acquisition. For this the digital data were at first converted to analogue followed by recalculation of the first 4-16 data points by linear prediction backward using 32 filter coefficients [20]. To improve the signal-to-noise ratio the corrected free induction decay was multiplied by an exponential window function using a line broadening factor of 80-150 Hz, depending on the linewidth of the resonance lines.…”

Methods of control and standardization of drugs containing progestogen hormones (A review)

“…A combination of the IH and t3C NMR data with the results of some other methods allowed six impurities to be identified in progesterone [54]; this work also reported for the first time on the 13C NMR spectra of 6-oxoprogesterone and 20[3-hydroxypregn-4-en-3-one. The IH and 13C NMR spectra of various progestogen hormones and related compounds were reported in [99 -107] and the 170 NMR spectrum of progesterone was presented in [108].…”