Bioinspired Synthesis of (−)‐Hunterine A: Deciphering the Key Step in the Biogenetic Pathway

Abstract

A concise, bioinspired, and enantioselective synthesis of (–)‐hunterine A, an odd 6/7/6/6/5 pentacyclic natural product, is described. The key step in the synthesis of this complex structure is an interim‐template directed 6‐exo selective epoxide ring‐opening reaction, which is interwoven with a hydrolysis step of the indolenine hemiaminal template to create the unusual 7‐membered azepine bridge motif. Our work not only refines the previously proposed biogenetic pathway, but also reveals the possible stereochemical prerequisite of the unique skeletal rearrangement, which provides a vantage point for understanding how (–)‐hunterine A is likely to be generated in nature.