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Open AccessArticle

Enantioselective Solvent-Free Synthesis of 3-Alkyl-3-hydroxy-2-oxoindoles Catalyzed by Binam-Prolinamides

Departamento de Química Orgánica, Instituto de Síntesis Orgánica, Universidad de Alicante, Apdo. 99, Alicante E-03080, Spain
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Academic Editor: Raquel Herrera
Molecules 2015, 20(7), 12901-12912; https://doi.org/10.3390/molecules200712901
Received: 15 June 2015 / Revised: 6 July 2015 / Accepted: 10 July 2015 / Published: 16 July 2015
(This article belongs to the Collection Recent Advances in Organocatalysis)
BINAM-prolinamides are very efficient catalyst for the synthesis of non-protected and N-benzyl isatin derivatives by using an aldol reaction between ketones and isatins under solvent-free conditions. The results in terms of diastereo- and enantioselectivities are good, up to 99% de and 97% ee, and higher to those previously reported in the literature under similar reaction conditions. A high variation of the results is observed depending on the structure of the isatin and the ketone used in the process. While 90% of ee and 97% ee, respectively, is obtained by using (Ra)-BINAM-l-(bis)prolinamide as catalyst in the addition of cyclohexanone and α-methoxyacetone to free isatin, 90% ee is achieved for the reaction between N-benzyl isatin and acetone using N-tosyl BINAM-l-prolinamide as catalyst. This reaction is also carried out using a silica BINAM-l-prolinamide supported catalyst under solvent-free conditions, which can be reused up to five times giving similar results. View Full-Text
Keywords: isatin; aldol; enantioselectivity; solvent-free; prolinamide; supported catalyst isatin; aldol; enantioselectivity; solvent-free; prolinamide; supported catalyst
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MDPI and ACS Style

Bañn-Caballero, A.; Flores-Ferrándiz, J.; Guillena, G.; Nájera, C. Enantioselective Solvent-Free Synthesis of 3-Alkyl-3-hydroxy-2-oxoindoles Catalyzed by Binam-Prolinamides. Molecules 2015, 20, 12901-12912.

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