title: Enantioselective solvent-free synthesis of 3-alkyl-3-hydroxy-2-oxoindoles catalyzed by binam-prolinamides.
abstract: 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.
authors.affiliation: Departamento de Química Orgánica, Instituto de Síntesis Orgánica, Universidad de Alicante, Apdo. 99, Alicante E-03080, Spain. abraham.banon@ua.es.
authors.forename: Abraham
authors.initials: A
authors.lastname: Bañn-Caballero
authors.affiliation: Departamento de Química Orgánica, Instituto de Síntesis Orgánica, Universidad de Alicante, Apdo. 99, Alicante E-03080, Spain. jflores@ua.es.
authors.forename: Jesús
authors.initials: J
authors.lastname: Flores-Ferrándiz
authors.affiliation: Departamento de Química Orgánica, Instituto de Síntesis Orgánica, Universidad de Alicante, Apdo. 99, Alicante E-03080, Spain. gabriela.guillena@ua.es.
authors.forename: Gabriela
authors.initials: G
authors.lastname: Guillena
authors.affiliation: Departamento de Química Orgánica, Instituto de Síntesis Orgánica, Universidad de Alicante, Apdo. 99, Alicante E-03080, Spain. cnajera@ua.es.
authors.forename: Carmen
authors.initials: C
authors.lastname: Nájera
mesh_terms: D002384:Catalysis; D003512:Cyclohexanones / Q000737:chemistry; D007211:Indoles / Q000138:chemical synthesis*; D007510:Isatin / Q000737:chemistry*; D007659:Ketones / Q000737:chemistry; D015394:Molecular Structure; D011392:Proline / Q000031:analogs & derivatives* / Q000737:chemistry; D013237:Stereoisomerism
chemical_list: D003512:Cyclohexanones; D007211:Indoles; D007659:Ketones; C036468:cyclohexanone; C442334:3-hydroxy-2-oxoindole; D007510:Isatin; D011392:Proline; C056291:prolinamide
keywords: aldol; enantioselectivity; isatin; prolinamide; solvent-free; supported catalyst