Practical synthetic methods of natural cardenolides are illustrated in the syntheses of xysmalogenin and digitoxigenin. The new routes employ pregn-14-en-20-one as key intermediate which was prepared by partial reduction of 14, 16-dien-20-one with triphenylstannane or triethylsilane. A general and efficient method was devised for obtaining cardenolides consisting of (1) 21-methylsulfenylation of pregnen-20-one, (2) the reaction of the resulting 21-methylthio derivative with bromoacetate and zinc, (3) alumina chromatography of epoxy ester obtained from the S-methylated Reformatsky product.
Synthesis and Evaluation of Novel Steroidal Oxime Inhibitors of P450 17 (17α-Hydroxylase/C17−20-Lyase) and 5α-Reductase Types 1 and 2
作者:Rolf W. Hartmann、Markus Hector、Samer Haidar、Peter B. Ehmer、Wolfgang Reichert、Joachim Jose
DOI:10.1021/jm001008m
日期:2000.11.1
isozymes 1 and 2, the progesterones 16, 17, 20, 21, and 23 showed marked inhibition, especially toward the type 2 enzyme. Compounds 17 and 20 were identified as potent dual inhibitors of both P45017 and 5 alpha-reductase. Tested for selectivity, the most potent P45017inhibitors 9, 10, and 14 showed no or only marginal inhibition of P450arom, P450 scc, and P450 TxA(2). Selected compounds were tested
Control of the stereochemistry of C14 hydroxyl during the total synthesis of withanolide E and physachenolide C
作者:M. Anees、S. Nayak、K. Afarinkia、V. Vinader
DOI:10.1039/c8ra08540d
日期:——
The stereochemical outcome of the epoxidation of Δ14–15 cholestanes with mCPBA is controlled by the steric bulk of a C17 substituent. When the C17 is in the β configuration, the epoxide is formed in the α face, whereas if the C17 is trigonal (flat) or the substituent is in the α configuration, the epoxide is formed in the β face. The presence of a hydroxyl substituent at C20 does not influence the