Oxidation of .beta.-anilinoacrylate alkaloids vincadifformine and tabersonine by Fremy's salt. A mechanistic insight into the rearrangement of Aspidosperma to Hunteria eburnea alkaloids
Synthesis of vinca alakaloids and realated compounds<b>98</b>. Oxidation with dimethyldioxirane of compounds containing the aspidospermane and quebrachamine ring system. A simple synthesis of (7<i>S</i>,20<i>S</i>)-(+)-rhazidigenine and (2<i>R</i>,7<i>S</i>,20<i>S</i>)-(+)-rhazidine
The oxidation of (-)-tabersonine (1) with dimethyldioxirane (DMD) in neutral and acidic medium gave 16-hydroxytabersonine-N-oxide (3) and the didehydrovincamine isomers 4 and 5, respectively. (+)-14,15-Didehydro-quebrachamine (7) furnished the hydroxyindolenine 9, and the pentacyclic derivative 11. (+)-Quebrachamine (8) and DMD in neutral medium gave (7S,20S)-(+)-rhazidigenine (12) which was converted