Bifunctional Squaramide-Catalyzed Asymmetric [3 + 2] Cyclization of 2-(1-Methyl-2-oxoindolin-3-yl)malononitriles with Unsaturated Pyrazolones To Construct Spirooxindole-Fused Spiropyrazolones.
J Org Chem
; 84(16): 10209-10220, 2019 Aug 16.
Article
em En
| MEDLINE
| ID: mdl-31318546
ABSTRACT
The present paper reports a highly stereoselective synthesis of spirooxindole-fused spiropyrazolones through the asymmetric [3 + 2] cyclization reaction of 2-(1-methyl-2-oxoindolin-3-yl)malononitriles with unsaturated pyrazolones under mild conditions. With only a 1 mol % bifunctional squaramide catalyst, a series of chiral dispirocyclic pyrazolone derivatives were attained in high yields (85-97%) with excellent stereoselectivities (up to >99% ee and in all cases >201 dr). Moreover, gram-scale synthesis and further transformation of the products were also demonstrated.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Idioma:
En
Revista:
J Org Chem
Ano de publicação:
2019
Tipo de documento:
Article