105078-97-5Relevant articles and documents
Synthesis of (25S)-2H1>Cholesterol and 1H N.m.r. Signal Assignments of the pro-R and pro-S Methyl Groups at C-25
Shujiro, Seo,Yohko, Yoshimura,Tomohiro, Satoh,Atsuko, Uomori,Ken'ichi, Takeda
, p. 411 - 414 (2007/10/02)
(25S)-2H1>Cholesterol (11) has been prepared from diosgenin (1), and the absolute configuration at C-25 of the crucial intermediate , (25R)-26-hydroxycholesterol (6), has been identified by X-ray crystallographic analysis.The two methyl groups at C-25 of cholesterol have been examined by 1H n.m.r. spectroscopy and the two sets of doublet methyl signals due to 27-H and 26-H have been observed at δH 0.862 and 0.866 downfield from the internal reference.The former was assigned to 27-H, the pro-R methyl group attached at C-25, and the latter to 26-H, the pro-S methyl group attached at C-25.The 13C n.m.r. signal assignments of the methyl groups at C-25 reported by Popjak were confirmed on the basis of the signals of the deuteriated cholesterol (11).