Regiodivergent Synthesis of Penta-Substituted Pyrroles through a Cascade [3 + 2] Cyclization of C‑Acylimines with Activated Alkynes and Aromatic Nucleophiles

Highly robust one-pot, four-component
cascade cyclization reaction
of α-keto aldehydes, anilines, activated alkynes, and aromatic
nucleophiles is developed to synthesize a diverse range of pharmaceutically
important penta-substituted pyrroles. The reaction proceeds through
the cascade cyclization of acylimines (in situ formed) with activated
alkynes and aromatic nucleophiles such as indoles, pyrroles, and naphthols
at room temperature under calcium­(II) catalysis with high yields and
broad substrate diversity.