Chemodivergent Syntheses of Pyrroles and 1-Pyrrolines from β-Amino Alcohols and Ketones Employing ADC and BH Strategies

We report an iridium-catalyzed chemodivergent strategy for the selective syntheses of pyrroles and 1-pyrrolines from β-amino alcohols and ketones by fine-tuning the catalyst loading and base under acceptorless dehydrogenative coupling (ADC) and borrowing hydrogen (BH) pathways. Whereas previous transition-metal-catalyzed ADC and BH protocols favor aromatized pyrroles due to their thermodynamic stability, our method uniquely enables controlled access to 1-pyrroline by suppressing aromatization. Mechanistic studies indicate that imine formation, Ir-mediated dehydrogenation, intramolecular cyclodehydration, and controlled hydrogen transfer are the key steps.