IOSR Journal of Applied Chemistry (IOSR-JAC) e-ISSN: 2278-5736.Volume 13, Issue 2 Ser. I (February. 2020), PP 34-48 www.iosrjournals.org DOI: 10.9790/5736-1302013448 www.iosrjournals.org 34 |Page Spectral Studies of Steroids Using Two-Dimensional NMR Spectroscopy SheebaShafi Department of nursing, college of applied medical science, King Faisal university -Al Hofuf, Al Hasa P.O. Box:400, Pin code 31982-KSA Abstract: During our four decades in the field of steroids research we have faced time and again various stereochemical problems while interpreting spectral data of the synthesized compounds. 2D-NMR spectroscopy now has given a new spectral technique to overcome the conformational uncertainty and justified the assignments of the spectral data. While writing this chapter we are fully aware of the fact that avoiding mathematical and other difficult parameter we are trying to study 2D-NMR spectroscopy taking the examples of steroidal compounds. For this purpose, we have selected steroidal compounds such as 3β-hydroxycholest-5-ene 6 (VI) 2α, 7α-dibromocholest-4-ene-3, 6-dione 7 (VII), 6-oxa-B-homo-5α-cholestan-7-one 8 (VIII), 3β-acetoxy-6- amino (N, N dimethyl)-cholest-5-ene 9 (IX), 3β-chloro-5α-cholestan-6-one 10 (X) and 3β-acetoxy-5, 6β-dibromo- 5α-cholestane 11 (XI), for homo and hetero, nuclear cosy NMR spectral studies. Keywords: 1 H- 1 HNMR, 2-DNMR, 13 CNMR, Spectroscopy, Steroids --------------------------------------------------------------------------------------------------------------------------------------- Date of Submission: 12-02-2020 Date of Acceptance: 28-02-2020 -------------------------------------------------------------------------------------------------------------------------------------- I. Introduction All the NMR spectra described up to now have two dimensions, the abscissa which corresponds to the frequency axis, from which one reads off the chemical shifts and the ordinate which gives the intensities of the signals. However, when we speak of a two-dimensional, 2D-NMR spectrum we understand this to mean a spectrum in which both the abscissa and the ordinate are frequency axis, with the intensities constitute a third dimension. Ifchemical shifts are plotted along one of the frequency axes and coupling constants along the other, we call this a two-dimensional (shift)-correlated NMR spectrum. From the practical NMR spectroscopist's point of view themost important 2D spectra of the latter type are those which show either 1 H- 1 H or 1 H- 13 C chemical shift correlations. During our four decades in the field of steroids research we have faced time and again various stereochemical problems while interpreting spectral data of the synthesized compounds. 2D-NMR spectroscopy now has given a new spectral technique to overcome the conformational uncertainty and justified the assignments of the spectral data. While writing this chapter we are fully aware of the fact that avoiding mathematical and other difficult parameter we are trying to study 2D-NMR spectroscopy taking the examples of steroidal compounds. For this purpose, we have selected steroidal compounds such as 3β-hydroxycholest-5-ene 6 (VI) 2α, 7α-dibromocholest-4-ene-3, 6-dione 7 (VII), 6-oxa-B-homo-5α-cholestan-7-one 8 (VIII), 3β-acetoxy-6- amino (N, N dimethyl)-cholest-5-ene 9 (IX), 3β-chloro-5α-cholestan-6-one 10 (X) and 3β-acetoxy-5, 6β-dibromo- 5α-cholestane 11 (XI), for homo and hetero, nuclear cosy NMR spectral studies. II. Experimental All melting points were observed on a Kofler hot block apparatus and are uncorrected. I. R. spectra were determined in KBr with JASCO A-100 spectrophotometer. NMR spectra were recorded in CDCI 3 on Varian XL-400 MHz. Mass spectra were measured on a JEOL JMS DX-300 mass spectrometer. TLC plates were coated with silica gel. A 20% aqueous solution of perchloric acid was used as spraying agent. Light petroleum ether refers toa fraction of b.p. 60-80°. NMR values were given in ppm (s = singlet, d = doublet, dd = double doublet, t = triplet). III. Result and Discussion 1 H- 1 H-NMR Homonuclear Cosy Spectral Studies of 3β-Hydroxy-Cholest-5-ene (VI) (Fig.8a): In 1 H- 1 H-NMR Homonuclear cosy spectral studies of 3β-hydroxy-cholest-5-ene (VI), normal one- dimensional spectrum is plotted alongside with the two axes (F1 and F2) of cosy spectrum which identify the complete chain of coupling protons. The important and pertinent point in 1 H- 1 H-NMR homonuclear cosy spectral are diagonal peak multiplets centered around the same F1 and F2 frequency coordinates which indicate the chemical shifts and cross peak multiplets which are centered around different F1 and F2 coordinates and
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Spectral Studies of Steroids Using Two-Dimensional …...Spectral studies of steroids using two-dimensional NMR spectroscopy DOI: 10.9790/5736-1302013448 37 |Page 2D-NMR spectral study
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