N‐Heterocyclic Carbene‐Catalyzed Atroposelective Synthesis of 5‐Indo‐1‐yl Pyran‐2‐ones with an N−C axis from Enals.

A variety of 5‐indo‐1‐yl pyran‐2‐ones with an N−C axis were prepared via a carbene‐catalyzed oxidative [3+3] annulation of indole‐1‐pyruvate esters and enals. Asymmetric construction of pyran‐2‐one ring from enals ensures the realization of this strategy. The resulting compounds were converted into axially chiral N‐arylindoles with an N−C axis via a cycloaddtion aromatization. [ABSTRACT FROM AUTHOR]