Stereocontrolled Divergent Total Syntheses of (+)-7-Deoxypancratistatin, (+)-7-Deoxy-<i>trans</i>-dihydronarciclasine, and (+)-Lycoricidine via Cyclic Boronic Ester-Mediated Diastereoselective Alkenylation

Stereocontrolled divergent total syntheses of Amaryllidaceae isocarbostyril alkaloids have been accomplished through the manipulation of the C(1) hydroxyl group from a common late-stage intermediate. Key features of the synthesis include (1) a cyclic boronic ester-mediated diastereoselective alkenylation for an early stage installation of the C(10b) stereocenter, (2) a chelation-controlled stereoselective <i>syn</i>-allylation to set the C(2) stereocenter, and (3) a rare regio- and stereoselective opening of <i>N</i>-Boc-aziridine followed by elimination to construct the allylic amine moiety.