N-Heterocyclic Carbene-Catalyzed Atroposelective Synthesis of Axially Chiral & alpha;-Carbolinones via Heterocycle Formation

An NHC-catalyzed atroposelective synthesis of axiallychiral & alpha;-carbolinonesfrom & alpha;,& beta;-unsaturated iminoindole derivatives and & alpha;-chloroaldehydeswas developed. The reaction proceeds through a cascade process including[4 + 2] annulation and then oxidative dehydrogenation with concomitantcentral-to-axial chirality conversion under mild conditions. The developedmethod opens a new avenue to efficiently access axially chiral & alpha;-carbolinonesin moderate to good enantioselectivities.

Automated summary

A NHC-catalyzed method for the atroposelective synthesis of axially chiral α-carbolinones from α,β-unsaturated iminoindole derivatives and α-chloroaldehydes was developed. The reaction involves a cascade process including [4 + 2] annulation and oxidative dehydrogenation, leading to a conversion of central-to-axial chirality under mild conditions. The developed method offers a new avenue for the efficient synthesis of axially chiral α-carbolinones with moderate to good enantioselectivities.