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Oxidative Asymmetric [2 + 3] Annulation of Aldehydes with Azomethine Imines Enabled by N-Heterocyclic Carbene Catalysis



Oxidative Asymmetric [2 + 3] Annulation of Aldehydes with Azomethine Imines Enabled by N-Heterocyclic Carbene Catalysis



Organic Letters 19(22): 6100-6103



An efficient asymmetric [2 + 3] annulation of simple aldehydes with N,N'-cyclic azomethine imines via oxidative N-heterocyclic carbene (NHC) catalysis is disclosed, affording bicyclic pyrazolidinones bearing two vicinal tertiary stereogenic centers with moderate to good yields (56-84% for 19 examples), good to excellent diastereoselectivities (>20:1 for 17 examples), and good to excellent enantioselectivities (66-98% for 19 examples). This direct α-carbon functionalization reaction of aldehyde can be readily performed on gram scale under mild conditions, and a five-membered transition state is proposed to rationalize the stereochemical outcome.

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Accession: 060060116

Download citation: RISBibTeXText

PMID: 29095623

DOI: 10.1021/acs.orglett.7b02948


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