Stereoisomeric Sugar-Derived Indolizines as Versatile Building Blocks: Synthesis of Enantiopure Di- and Tetrahydroxyindolizidines
作者:Claudio Paolucci、Lucia Mattioli
DOI:10.1021/jo0016428
日期:2001.7.1
The synthesis of the sugar-derived (1S,2R,8aR)-1,2-di-O-isopropylidene-1,2,3,5,6,8a-hexahydro-5- oxoindolizine (8) and by analogy of the corresponding stereoisomers ent-8 and ent-7, an epimer at C-2 of ent-8, has been accomplished in a straightforward manner. The carbon-carbon double bond and the carbonyl functionalities on the six-membered ring make these nitrogen-containing heterocycles useful building blocks for the efficient preparation of a variety of enantiopure polyhydroxylated indolizidines of interest for their glycosidase inhibitory activity. We report here the synthesis of 2,8a-diepilentiginosine 12 from 8 and the preparation of stereoisomeric 1,2,7,8-tetrahydroxyindolizidines 9-11 performed by OsO4-catalyzed double bond syn dihydroxylation of 7 and 8, followed by deoxygenation of the amide group.