Spencer, Thomas A. and Li, Dansu and Russel, Jonathon S. and Tomkinson, Nicholas C. O. and Willson, Timothy M. (2000) Further studies on the synthesis of 24(S),25-epoxycholesterol. A new, efficient preparation of desmosterol. Journal of Organic Chemistry, 65 (7). pp. 1919-1923. ISSN 0022-3263Full text not available in this repository. (Request a copy from the Strathclyde author)
Efforts to improve the synthesis of 24(S),25-epoxycholesterol from stigmasterol have included identification of 6α-hydroxy-i-steroid (I) (R1 = OH, R2 = αOH) as a byproduct from the ozonolysis of steroid (II) and an attempt to effect conversion of sulfone I (R1 = SO2Ph, R2 = βOMe) (III) to diol (IV) via Payne rearrangement and nucleophilic trapping of (S)-2-hydroxymethyl-3,3-dimethylepoxide, which led instead to (V) (R3 = α or β OH) (97% yield). A more efficient synthesis of 24(S),25-epoxycholesterol was achieved via coupling of cuprate I (R1 = CuCNLi, R2 = βOMe) (VI) with allylic acetate H2C=CHCMe2OAc to give 73% of I (R1 = CH2CH=CMe2, R2 = βOMe) (VII), in the most efficient conversion yet of a C22 intermediate to desmosterol or its acetate.
|Keywords:||desmosterol , 25-epoxycholesterol , stigmasterol, Chemistry, Organic Chemistry|
|Subjects:||Science > Chemistry|
|Department:||Faculty of Science > Pure and Applied Chemistry|
|Depositing user:||Pure Administrator|
|Date Deposited:||20 Oct 2011 15:14|
|Last modified:||06 Jan 2017 10:06|