Total Synthesis of Vinorine

One-Pot Reaction Sequence: N-Acylation/Pictet-Spengler Reaction/Intramolecular [4 + 2] Cycloaddition/Aromatization in the Synthesis of β-Carboline Alkaloid Analogues

One-pot synthesis of tetrahydro-β-carbolines, fused with an isoindole core, was proposed starting from maleic anhydride and azomethines easily available from tryptamines and 3-(hetaryl)acroleins. This sequence includes four key steps: an acylation of the aldimine with maleic anhydride, a Pictet-Spengler cyclization, an intramolecular Diels-Alder reaction, and a concluding [1,3]-H shift. As a result, six- or seven-nuclear alkaloid-like heterocyclic systems, containing a benzo[1,2]indolizino[8,7-b]indole fragment annulated with furan, thiophene, or pyrrole, are formed in a diastereoselective manner.

Total Synthesis of Tetracyclic Spirooxindole Alkaloids via a Double Oxidative Rearrangement/Cyclization Cascade

Skeleton rearrangement could rapidly transfer simple molecules to complex structures and has significant potential in the total synthesis of natural products. We developed a one-pot reaction cascade of double oxidative rearrangement of furan and indole followed by a nucleophilic cyclization that was successfully applied for the formal synthesis of rhynchophylline/isorhynchophylline and the first total synthesis of (±)-7(R)-geissoschizol oxindole/(±)-7(S)-geissoschizol oxindole. In addition, the geissoschizol oxindoles were revised to their C3 epimers, and the mechanism for the reversed stereochemistry through the retro-Mannich/Mannich cascade was proposed and supported by density functional theory calculations.

Asymmetric Synthesis of (+)-Vellosimine Enabled by a Sequential Nucleophilic Addition/Cyclization Process

Herein, we achieved the asymmetric synthesis of (+)-vellosimine in 13 steps (longest linear sequences, LLS). This synthesis featured a sequential nucleophilic addition/cyclization process, which provided an efficient protocol for synthesizing a range of indole fused azabicyclo[3.3.1]nonane. Additionally, a SmI2-mediated reductive cyclization of ketone with an attached α,β-unsaturated ester for constructing the strained quinuclidine moiety was also highlighted.