Total Syntheses of (−)‐Minovincine and (−)‐Aspidofractinine through a Sequence of Cascade Reactions
Szilárd Varga, Péter Angyal, Gábor Martin, Orsolya Egyed, Tamás Holczbauer, Tibor Soós
Abstract
Abstract We report 8‐step syntheses of (−)‐minovincine and (−)‐aspidofractinine using easily available and inexpensive reagents and catalyst. A key element of the strategy was the utilization of a sequence of cascade reactions to rapidly construct the penta‐ and hexacyclic frameworks. These cascade transformations included organocatalytic Michael‐aldol condensation, a multistep anionic Michael‐S N 2 cascade reaction, and Mannich reaction interrupted Fischer indolization. To streamline the synthetic routes, we also investigated the deliberate use of steric effect to secure various chemo‐ and regioselective transformations.
Topics & Concepts
CascadeSteric effectsRegioselectivityAldol reactionReagentCombinatorial chemistryChemistrySequence (biology)Aldol condensationCascade reactionCatalysisOrganic chemistryStereochemistryChromatographyBiochemistryAlkaloids: synthesis and pharmacologyTraditional and Medicinal Uses of AnnonaceaeMicrobial Natural Products and Biosynthesis