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 alpha-amino acid derivatives from alpha 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 Cuacetoacetate 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 alpha-amino acid derivatives.

Automated summary

We have developed a Cu-catalyzed cross-electrophilic coupling reaction for the synthesis of alpha-amino acid derivatives using alpha diazoesters and O-benzoyl hydroxylamines. Cu(OAc)2 is used as the catalyst and polymethylhydrosilane (PMHS) as the hydride reagent. The reaction demonstrates excellent functional group compatibilities. The formation of a Cuacetoacetate complex was confirmed by ESI-MS analysis, and radical trap experiments suggest the involvement of nitrogen-centered radicals as intermediates. This strategy provides a simple and cost-effective approach for the synthesis of alpha-amino acid derivatives.