Asymmetric Construction of Spiropyrazolone Skeletons via Amine‐Catalyzed [3+3] Annulation

Here we report a secondary amine‐catalyzed, highly enantioselective [3+3] cyclization reaction of α‐alkylidene pyrazolinones and α,β‐unsaturated aldehydes, which facilely delivers a variety of enantioenriched spiropyrazolones showing structural and stereochemical complexity. The reaction uses an imi...

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Bibliographic Details
Published in:Advanced synthesis & catalysis 2018-01, Vol.360 (2), p.229-234
Main Authors: Leng, Hai‐Jun, Li, Qing‐Zhu, Zeng, Rong, Dai, Qing‐Song, Zhu, Hong‐Ping, Liu, Yue, Huang, Wei, Han, Bo, Li, Jun‐Long
Format: Article
Language:English
Subjects:
Aldehydes
Alkylidene
annulation
asymmetric synthesis
Chemical reactions
Organic chemistry
organocatalysis
pyrazolones
spirocyclic compounds
Substrates
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Summary:Here we report a secondary amine‐catalyzed, highly enantioselective [3+3] cyclization reaction of α‐alkylidene pyrazolinones and α,β‐unsaturated aldehydes, which facilely delivers a variety of enantioenriched spiropyrazolones showing structural and stereochemical complexity. The reaction uses an iminium ion activation strategy to activate both the β‐ and ipso‐positions of the enals as dielectrophilic sites. A broad range of substrates are compatible with this mild reaction system.
ISSN:1615-4150
1615-4169
DOI:10.1002/adsc.201701035