Aggregation‐Induced Asymmetric Synthesis of 2,3‐Dihydrobenzofurans by [4 + 1] Annulation with Substituted Salicyl N‐Phosphonyl Imines

The aggregation‐induced asymmetric synthesis of trans‐2,3‐dihydrobenzofuran compounds was achieved via the reaction of salicyl N‐phosphonyl imines with sulfur ylide. This transformation proceeds through a [4 + 1] annulation pathway, affording products in good to excellent yields with tunable diastereoselectivities. By employing various THF/EtOH cosolvent systems in conjunction with group‐assisted purification (GAP) chemistry, the conventional aggregation cosolvent systems were shown to play a crucial role in enhancing diastereoselectivity and modulating aggregate formation. This was supported by studies involving aggregation‐induced emission (AIE), aggregation‐induced polarization (AIP), and dynamic light scattering (DLS). The developed protocol provides a practical and versatile synthetic approach to 2,3‐dihydrobenzofuran scaffolds, highlighting the utility of aggregation‐induced asymmetric synthesis (AIAS) as a powerful strategy for achieving stereocontrol.