Eosin-Y/Cu(OAc)2-catalyzed aerobic oxidative coupling reactions of glycine esters in the dark

Catalytic aerobic oxidative coupling reactions of glycine esters with beta-keto acids, indoles, naphthols, and pyrrole have been realized at ambient temperature via the manipulation of the ground state reactivity of eosin-Y in the presence of Cu(OAc)(2) in the dark. This method delivers structurally diverse unnatural amino acid derivatives under mild reaction conditions. UV-vis absorption spectroscopy, cyclic voltammetry, X-ray photoelectron spectroscopy, high-resolution mass spectrometry, and control experiments were performed to formulate a plausible mechanistic pathway. The step economy, broad substrate scope, use of air as a green oxidant, and operationally simple set-up make this protocol highly appealing for both academic and industrial applications.

Automated summary

Catalytic aerobic oxidative coupling reactions of glycine esters with various substrates were achieved at low temperature using the ground state reactivity of eosin-Y. This method allows the synthesis of structurally diverse unnatural amino acid derivatives and offers advantages such as step economy, broad substrate scope, and operational simplicity.