Synthetic and mechanistic approaches to biologically potent aminoglycosides via diversified aziridination patterns

268 p.The flexible installation of a sulfamate ester group on different positions of the glycal scaffold has been highlighted to be a new concept for synthesizing a- and P-aminoglycosides. The methodology incorporated three relevant steps: 1) the introduction of the sulfamate ester on the C3, C4, or C6 position of the glycal, 2) the intramolecular rhodium-catalyzed aziridination, and 3) regio- and stereoselective ring-opening of aziridines with readily available nucleophiles. With this rational design of substrates, the possibility, reactivity and limitation of forming aziridine-ring intermediates from 1, 2, and 3 have been performed based on the results from experimental observations and DFT calculations.DOCTOR OF PHILOSOPHY (SPMS

Syntheses of 3-O-Demethylthalicthuberine and N-Acetyl-seco-N-methyllaurotetanine

The structures previously assigned to the phenanthrene alkaloids 3-O-demethylthalicthuberine and N-acetyl-seco-N methyllaurotetanine have been confirmed by total syntheses in which the key step involved formation of ring C of the aporphine alkaloids (±)-isodomesticine and O-benzyl-N-methyllaurotetanine by a radical-initiated cyclization. Opening of ring B of (±) isodomesticine with methyl chloroformate and subsequent reduction of the N-carbomethoxy group afforded 3-O demethylthalicthuberine. Similarly, ring-B opening of N-methyllaurotetanine with acetyl bromide followed by hydrolysis afforded N-acetyl-seco-Nmethyllaurotetanine

Total Synthesis and the Biological Activities of (±)-Norannuradhapurine

molecule