Synthesis of Pyrido[2,3‐b]indoles via Brønsted‐Acid‐Promoted Decarboxylative Annulation of 3‐Bromopropenals and Ethyl 2‐Amino‐1H‐indole‐3‐carboxylates

The present methodology describes a versatile pathway to furnish α‐carbolines from relatively stable 2‐amino indole derivatives and 3‐bromopropenal. High substrate tolerance, nonmetallic, more efficient, and mild reaction conditions are important aspects. Annulation: α‐Carboline derivatives were synthesized via Brønsted‐acid‐promoted decarboxylative annulation of 3‐bromopropenals and ethyl 2‐amino‐1H‐indole‐3‐carboxylates)