Visible Light-Driven Flexible Synthesis of α‑Alkylated Glycine Derivatives Catalyzed by Reusable Covalent Organic Frameworks

Herein, we report a heterogeneous visible light-driven preparation of α-alkylated glycine derivatives. This approach employed a β-ketoenamine-linked covalent organic framework (2D-COF-4) as the heterogeneous photocatalyst and N-hydroxy phthalimide (NHPI) esters as the alkyl radical sources. Numerous glycine derivatives, including dipeptides, were precisely and efficiently alkylated under visible light-driven reaction conditions. Based on the excellent photoactivity and organic reaction compatibility of 2D-COF-4, this alkylation could proceed flexibly in a green solvent (ethanol) without any other additives. The photocatalyst and phthalimide were fruitfully recycled with a simple workup procedure, revealing a high ecoscale value and low environmental factor (E-factor).