see text] The first asymmetric totalsynthesis of a structurally novel cis-cyclopent[c]isoxazolidine alkaloid, (-)-pyrinodemin A (3), which exhibits potent cytotoxicity, has been accomplished through a highly diastereoselective intramolecular nitrone-olefin cycloaddition reaction as the key step. Thus, it has been found that the hitherto unknown absoluteconfiguration of pyrinodemin A is as indicated