Unified Synthesis of 2-Isocyanoallopupukeanane and 9-Isocyanopupukeanane through a "Contra-biosynthetic" Rearrangement

Angew Chem Int Ed Engl. 2024 Jan 22;63(4):e202317348. doi: 10.1002/anie.202317348. Epub 2023 Dec 20.

Abstract

Herein, we describe our synthetic efforts toward the pupukeanane natural products, in which we have completed the first enantiospecific route to 2-isocyanoallopupukeanane in 10 steps (formal synthesis), enabled by a key Pd-mediated cyclization cascade. This subsequently facilitated an unprecedented bio-inspired "contra-biosynthetic" rearrangement, providing divergent access to 9-isocyanopupukeanane in 15 steps (formal synthesis). Computational studies provide insight into the nature of this rearrangement.

Keywords: Carbocation Rearrangement; Chiral Pool; Cyclization Cascade; Natural Product Synthesis; Sesquiterpenes.