C‐H Functionalization of Amino Alcohols by Osmium Tetroxide/NMO or TPAP/NMO: Protecting Group‐Free Synthesis of Indolizidines (–)‐223AB and 3‐epi‐(–)‐223AB.

The oxidative cyclization of amino alcohols by osmium tetroxide/NMO or tetrapropylammonium perruthenate (TPAP)/NMO was found to provide an N,O‐acetal moiety through the trapping of the resulting iminium ion by the alcohol. These two transformations were demonstrated in the synthesis of indolizidines (–)‐223AB and 3‐epi‐(–)‐223AB. [ABSTRACT FROM AUTHOR]