Cu-Catalyzed Cross-Electrophilic Coupling of α-Diazoesters with O -Benzoyl Hydroxylamines for the Synthesis of Unnatural N -Alkyl α-Amino Acid Derivatives.

We describe a Cu-catalyzed cross-electrophilic coupling reaction for synthesizing α-amino acid derivatives from α-diazoesters with O -benzoyl hydroxylamines with Cu(OAc) 2 as the catalyst and polymethylhydrosilane (PMHS) as the hydride reagent. Excellent functional group compatibilities were demonstrated. With ethyl 2-diazo-3-oxobutanoate as the precursor, a Cu-acetoacetate complex has been characterized by ESI-MS analysis. Results from the radical trap experiments are consistent with the intermediacy of nitrogen-centered radicals. This strategy offers a simple and inexpensive synthesis of α-amino acid derivatives.