Organocatalytic\nAsymmetric\n[3 + 2] Cyclization: Enantioselective\nSynthesis of α‑Indolyl Pyrrolo[1,2-a]indole Scaffolds

A novel asymmetric [3 + 2] cyclization\nof α-indolyl propargylic\nalcohols with 3-alkyl-1H-indoles via chiral phosphoric acid catalysis\nhas been established. This strategy allowed the synthesis of chiral\nα-indolyl pyrrolo[1,2-a]indole derivatives with high yields\n(up to 91%) and excellent enantioselectivities (up to 99% ee), facilitating\nboth the reaction activity and enantioselectivity by using the solvent\nof CH<sub>3</sub>CFCl<sub>2</sub>. Significantly, this protocol will\nprovide an effective synthetic approach for constructing enantioenriched\nα-indolyl pyrrolo[1,2-a]indole cores of antimalarial natural\nproduct isoborreverine analogues.