Total Synthesis of (±)-Marsupellins A and B via Acetoxymarsupellone Using an Intramolecular Reductive Cyclization of Epoxycyanohydrin Derivative with Cp2TiI

Total Syntheses of (±)-Acetoxymarsupellone and (±)-Marsupellins A, B, and D Enabled by a Reductive Cyclization and Semipinacol Rearrangement Strategy

We report herein the total syntheses of three marsupellin-family sesquiterpenoids, (±)-acetoxymarsupellone and (±)-marsupellins B and D, in 14-19 steps from our known precursor, making marsupellin A also accessible from marsupellin B through a known procedure. The critical tricyclic framework bearing the challenging C7 bridgehead all-carbon quaternary center is strategically constructed through a Ti-mediated reductive cyclization and semipinacol rearrangement sequence. This study provides a general approach to the syntheses of (ent-)longipinane-type molecules.

Synthesis of Succinonitrile Derivatives by Homocoupling from Cyanohydrin Derivatives with a Low-Valent Titanium Reagent

A method is described for synthesizing succinonitrile derivatives bearing alkyl or aryl substituents from cyanohydrin derivatives using low-valent titanium. The active species in this reaction is proposed to be a resonance hybrid of the Ti^IV nitrile enolate and Ti^III alkyl radical.