stereocontrolled strategy toward the total synthesis of isoprostanes based on a bicyclic alpha,beta-epoxy ketone intermediate 6. Bicyclo[3.3.0]octene scaffold permitted stereodirection of reagents allowing stereoselective epoxidation, diastereoselective ketone reduction, and regioselective epoxide opening otherwise not accessible with a simple cyclopentene framework.
Stereodivergent Synthesis of All 15-F<sub>2</sub> Isoprostanes
作者:Thomas O. Schrader、Marc L. Snapper
DOI:10.1021/ja027154u
日期:2002.9.1
Isoprostanes, lipid metabolites generated from free radical oxidation of membrane-bound arachidonic acid, have been detected in organisms subjected to oxidative stress; however, the function and cellular targets of the isoprostanes are unclear. As an initial step toward studying the biological role of these molecules, we report the preparation of all known and anticipated 15-F2 isoprostanes. The stereodivergent strategy to the complete isoprostane library features a ring-opening metathesis to introduce the cis-alkyl side chains that are characteristic of this class of molecules. Resolution to the individual stereoisomers can be accomplished by either a catalytic asymmetric reduction or an auxiliary-based separation protocol. In either case, the individual isomers can be converted to the corresponding 15-F2 isoprostanes through a straightforward functionalization of the carboxylic acid-containing side chain. The availability of this complete 15-F2 isoprostane library, containing both known and anticipated lipid metabolites, allows for the first time the side-by-side evaluation of these compounds in a variety of biological assays.
Synthesis of the four enantiomerically-pure isomers of 15-F2t-isoprostane
作者:Douglass F. Taber、Kazuo Kanai
DOI:10.1016/s0040-4020(98)83038-x
日期:1998.9
Syntheses of the four enantiomerically-pure isomers of 15-F2t-isoprostane are described. The key step is the lipase-mediated resolution of a pseudo-meso diol, to give the regioisomeric acetates in high enantiomeric purity. Improved procedures for the preparation of the pseudo-meso diol are also reported.