Synthesis of (–)-Kopsifoline A and (+)-Kopsifoline E

We report the first total synthesis of (–)-kopsifoline A and (+)-kopsifoline E. Our synthetic strategy features a biogenetically inspired regioselective C17-functionalization of a versatile intermediate containing the pentacyclic core of aspidosperma alkaloids. While this advance intermediate provides (–)-kopsifoline D via C3–C21 bond formation, regioselective C17-boronation of its indoline substructure prior to introduction of the F-ring enables access to (–)-kopsifoline A and (+)-kopsifoline E. The vinylogous urethane substructure of the key intermediate was critical in C17-boronation over a competing C7-boronation in related indole derived substrates. After oxidation of the C17–B bond to introduce the C17-ether, the C3–C21 bond of the targets is secured under the Mitsunobu reaction conditions with the vinylogous urethane as the nucleophilic component.

Total synthesis study of rauvomines A and B: construction of the pentacyclic core structure

The fifth ring of rauvomines can be annulated via a Mukaiyama-Aldol reaction as a new strategy for sarpagine scaffold construction.

Progress towards the synthesis of aconitine: construction of the AE fragment and attempts to access the pentacyclic core

We reported the first successful preparation of fully functionalized aconitine AE fragment and attempts to access the pentacyclic skeleton of aconitine via radical cascade.