66414-44-6Relevant articles and documents
A concise synthesis of 25-Hydroxycholesterol from hyodesoxycholic Acid
Jin, Can,Wang, Yulei,Sun, Bin,Su, Weike
, p. 96 - 99 (2018/03/21)
A simple, efficient and economical method has been developed for the synthesis of 25-hydroxycholesterol in seven steps from hyodesoxycholic acid with an overall yield of 39%. The preparation of the 3β-tetrahydropyranyloxychol-5-en-24-al from 3β-tetrahydropyranyloxychol-5-en-24-oic acid methyl ester with di-isobutylaluminium hydride was achieved instead of using the conventional two-step reaction, thus avoiding the use of the toxic oxidant CrO3. The terminal product was obtained by hydroxybromination of desmosterol with N-bromosuccinimide/H2O, followed by reduction and deprotection of the halohydrins with LiAlH4. This simplified route gave an increased overall yield and used economical and environmentally benign reagents.
Stereochemistry of Yeast Δ24-sterol methyl transferase
Acuna-Johnson, Adriana P.,Oehlschlager, Allan C.,Pierce, Aldona M.,Pierce Jr., Harold D.,Czyzewska, Eva K.
, p. 821 - 832 (2007/10/03)
S-Adenosyl-1-methionine:Δ24-sterol methyl transferase (24-SMT) mediates introduction of the C-28 carbon of yeast sterols. It has been shown that sulfonium analogues of the presumptive cationic intermediates of the methylenation reaction are potent in vivo and in vitro inhibitors of this process. In the presence of these inhibitors, cultures of yeast produced increased proportions of zymosterol, the natural substrate of the enzyme, while proportions of ergosterol and ergostatetraenol were decreased. New C27-sterol metabolites were also found. The in vivo inhibitory power of the analogues [I50 (μM)] was determined from the proportion of C-24 methylated sterols to C-24 nonmethylated sterols in treated cultures to be in the following order: 25-thiacholesteryl iodide (0.07) > 24(S)-methyl-25-thiacholesteryl iodide (0.14) > 24(R)-methyl-25-thiacholesteryl iodide (0.25). kinetic inhibition as revealed by radiolabeled S-adenosyl-1-methionine (SAM), crude enzyme and 25-thiacholesteryl iodide revealed this inhibitor to be uncompetitive with respect to zymosterol and competitive with respect to SAM. The greater inhibitory power of 24(S)-methyl-25-thiacholesteryl iodide compared to 24(R)-methyl-25-thiacholesteryl iodide suggests that methyl donation to Δ24 occurs from the si face. When considered in conjunction with Arigoni's previous work, the present results infer the methylenation mediated by yeast 24-SMT proceeds by alkylation from the si face of Δ24 followed by migration of a hydrogen from C-24 to C-25 across the re face and final loss of a hydrogen from C-28 on the re face.
Stereoselective Introduction of Hydroxy Groups into the Cholesterol Side Chain. Preparation of (24R)- and (24S)-24,25-Dihydroxy- and (25R)- and (25S)-25,26-Dihydroxyvitamin D3 by Asymmetric Synthesis
Koizumi, Naoyuki,Ishiguro, Masaji,Yasuda, Mitsuhiro,Ikekawa, Nobuo
, p. 1401 - 1410 (2007/10/02)
24,25-Epoxy-26-hydroxy-3β-tetrahydropyranyloxycholest-5-enes (7a) and (8a), prepared by asymmetric epoxidation of the allylic alcohol (4), and 24-hydroxy-3β-tetrahydropyranyloxycholesta-5,25-dienes (11) and (12), synthesized by asymmetric reduction of the enone (6), were stereoselectively converted into 25,26-and 24,25-dihydroxycholesterol derivatives, which could be transformed into 25,26- and 24,25-dihydroxyvitamin D3.The highly stereoselective epoxide cleavage of 26-benzoyloxy-24,25-epoxides (7b), (8b), (25), and (26) was found to proceed with retention at C-24.
