We have developed a novel one-pot synthetic method for regioselective and stereoselective amination through the reaction of various ethers with chlorosulfonyl isocyanate (CSI) and have extended its application to organic synthesis. In this presentation, we report a stereoselective total synthesis of the (-)-Lentiginosine, a dihydroxylated indolizidine alkaloid isolated from the leaves of Astragalus lentiginosus, which has shown anti-HIV activity and powerful aminoglucosidase inhibition (IC₅₀ 5 ¥ìg/mL). Asymmetric total synthesis of (-)-Lentiginosine was accomplished from D-lyxose in straightforward 11steps (26% overall yield). Key steps in this route are the regioselective and stereoselective introduction of N-protected amino group using our CSI reaction to cinnamyl polybenzyl ether and a ring-closing metathesis (RCM) approach employing the second generation Grubbs catalyst. We also describe the synthesis of 1,4-Dideoxy-1,4-imino-D-arabinitol (DAB1), poly-hydroxylated pyrrolidine alkaloid isolated from both Angylocalyx boutiqueanus and Arachniodes standishii, which was reported to be a powerful inhibitor of a range of yeast ¥á-glycosidases.