Diastereo- and atroposelective synthesis of N-arylpyrroles enabled by light-induced phosphoric acid catalysis.

The C-N axially chiral N-arylpyrrole motifs are privileged scaffolds in numerous biologically active molecules and natural products, as well as in chiral ligands/catalysts. Asymmetric synthesis of N-arylpyrroles, however, is still challenging, and the simultaneous creation of contiguous C-N axial and central chirality remains unknown. Herein, a diastereo- and atroposelective synthesis of N-arylpyrroles enabled by light-induced phosphoric acid catalysis has been developed. The key transformation is a one-pot, three-component oxo-diarylation reaction, which simultaneously creates a C-N axial chirality and a central quaternary stereogenic center. A broad range of unactivated alkynes were readily employed as a reaction partner in this transformation, and the N-arylpyrrole products are obtained in good yields, with excellent enantioselectivities and very good diastereoselectivities. Notably, the N-arylpyrrole skeletons represent interesting structural motifs that could be used as chiral ligands and catalysts in asymmetric catalysis.