Enantioselective Total Synthesis of (+)‐Incargranine A Enabled by Bifunctional Iminophosphorane and Iridium Catalysis

Abstract

AbstractHerein we report the first enantioselective total synthesis of (+)‐incargranine A, in nine steps. The total synthesis was enabled by an enantioselective intramolecular organocatalysed desymmetrising Michael addition of a malonamate ester to a linked dienone substrate that established pivotal stereocentres with excellent enantio‐ and complete diastereoselectivity. Furthermore, a key hemiaminal intermediate was accessed by developing an iridium‐catalysed reductive cyclisation, and the scope of this transformation was explored to produce a range of bicyclic hemiaminal motifs. Once installed, the hemiaminal motif was used to initiate a biomimetic cascade to access the natural product directly in a single step.