Chiral π–Cu(II) Catalysts for the Enantioselective α‑Amination of N‑Acyl-3,5-dimethylpyrazoles

We report the highly enantioselective α-amination of N-acyl-3,5-dimethylpyrazoles with dialkyl azodicarboxylates, catalyzed by in situ generated π–Cu­(II) complexes that consist of Cu­(OTf)2 and N-(5H-dibenzo­[a,d]­[7]­annulen-5-yl)-l-alanine-derived amides, to give the corresponding products as d-α...

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Veröffentlicht in:Organic letters 2022-10, Vol.24 (41), p.7685-7689
Hauptverfasser: Nishimura, Kazuki, Ogura, Yoshihiro, Takeda, Kazuki, Guo, Weiwei, Ishihara, Kazuaki
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Sprache:eng
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Zusammenfassung:We report the highly enantioselective α-amination of N-acyl-3,5-dimethylpyrazoles with dialkyl azodicarboxylates, catalyzed by in situ generated π–Cu­(II) complexes that consist of Cu­(OTf)2 and N-(5H-dibenzo­[a,d]­[7]­annulen-5-yl)-l-alanine-derived amides, to give the corresponding products as d-α-amino acid derivatives (up to >99% yield and 99% ee). The site-selectivity and enantioselectivity can be satisfactorily explained by the coordination of dialkyl azodicarboxylate with π–Cu­(II) complex. The synthetic potential of this one-pot transformation to the α-amino ester is also described.
ISSN:1523-7060
1523-7052
DOI:10.1021/acs.orglett.2c03249