Stereoisomeric sugar-derived indolizines as versatile building blocks: synthesis of enantiopure di- and tetrahydroxyindolizidines.
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 C2 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.
Paolucci
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Department of Organic Chemistry "A. Mangini", University of Bologna, Viale Risorgimento 4, I-40136 Bologna, Italy. paolucci@ms.fci.unibo.it
Mattioli
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D004791:Enzyme Inhibitors / Q000138:chemical synthesis; D006026:Glycoside Hydrolases / Q000037:antagonists & inhibitors; D007212:Indolizines / Q000138:chemical synthesis*; D013237:Stereoisomerism
D004791:Enzyme Inhibitors; D007212:Indolizines; D006026:Glycoside Hydrolases