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1.
J Org Chem ; 77(14): 6208-14, 2012 Jul 20.
Artículo en Inglés | MEDLINE | ID: mdl-22720976

RESUMEN

A primary amine-thiourea organocatalyzed intramolecular Michael addition access was developed for the synthesis of trans-dihydrobenzofurans. Under the catalysis of an (R,R)-1,2-diphenylethylamine derived primary amine-thiourea bearing a glucosyl scaffold, the corresponding trans-dihydrobenzofurans were obtained in high yields with excellent level of enantioselectivities (94 to >99% ee). Moreover, an in situ isomerization occurring at high temperature gave good to excellent trans/cis ratios as well (trans/cis: 84/16-96/4).


Asunto(s)
Aminas/química , Benzofuranos/síntesis química , Tiourea/química , Benzofuranos/química , Estructura Molecular , Estereoisomerismo
2.
J Org Chem ; 76(10): 4119-24, 2011 May 20.
Artículo en Inglés | MEDLINE | ID: mdl-21463004

RESUMEN

By employing a cinchonine-based thiourea as catalyst, highly enantioselective Michael addition reactions of 2-hydroxy-1,4-naphthoquinone to ß,γ-unsaturated α-ketophosphonates were realized. The reaction afforded the corresponding ß-substituted carboxylates in excellent yields with high levels of enantioselectivities (94->99% ee) upon quenching the generated parent structures with DBU and MeOH as a second nucleophile.

3.
J Org Chem ; 76(10): 3872-9, 2011 May 20.
Artículo en Inglés | MEDLINE | ID: mdl-21466168

RESUMEN

Based on different chiral diamine skeletons, a series of bifunctional primary amine-thiophosphoramides were synthesized and screened as the catalysts for the asymmetric Michael addition of acetone to both aromatic and aliphatic nitroolefins. Under the catalysis of a thiophosphoramide derived from 1,2-diphenylethane-1,2-diamine, the corresponding adducts were obtained in high yields (up to >99%) with excellent enantioselectivities (97-99% ee) under mild reaction conditions. Moreover, the catalyst could be recovered via simple phase separation and reused at least five times without any loss of both catalytic activity and stereocontrol.

4.
Org Lett ; 10(9): 1707-10, 2008 May 01.
Artículo en Inglés | MEDLINE | ID: mdl-18396893

RESUMEN

A novel bifunctional chiral thiourea organocatalyst bearing a glycosyl scaffold and a tertiary amino group was synthesized starting from readily available alpha-D-glucose. This thiourea was proven to be an effective organocatalyst for the asymmetric aza-Henry reaction between N-Boc imines and nitromethane. The corresponding adducts were obtained in good to excellent yields with excellent enantioselectivities (up to 99.8% ee). In addition, the reaction of nitroethane also proceeded smoothly with excellent enantioselectivity, albeit with low to good diastereoselectivities.

5.
Org Lett ; 4(26): 4723-5, 2002 Dec 26.
Artículo en Inglés | MEDLINE | ID: mdl-12489971

RESUMEN

[reaction: see text] In homogeneous H(2)O/solvent medium, the reaction rate of aromatic aldehydes and acrylonitrile or acrylate was greatly accelerated, which led to shorter reaction time, lower reaction temperature, and higher yield. In this reaction, Me(3)N, DMAP, DABCO, and urotropine were good catalysts. Except for low-carbon alcohols, tetrahydrofuran, 1,4-dioxane, and acetonitrile could be chosen as the solvent. Under this condition, the diastereoselective reaction of nitrobenzaldehyde and L-menthyl acrylate was realized with 88-99% de.

6.
Chem Asian J ; 8(9): 2204-10, 2013 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-23728825

RESUMEN

An efficient procedure for the stereocontrolled construction of 2H-thiopyrano[2,3-b]quinoline scaffolds has been developed, starting from simple compounds. The domino Michael/aldol reactions between 2-mercaptobenzaldehydes and enals, promoted by chiral diphenylprolinol TMS ether, proceed with excellent chemo- and enantioselectivity to give the corresponding synthetically useful and pharmaceutically valuable 2H-thiopyrano[2,3-b]quinolines in high yields with 90-99 % ee.

7.
Chem Asian J ; 8(11): 2859-63, 2013 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-23934622

RESUMEN

A highly diastereo- and enantioselective cyclopropanation of ß,γ-unsaturated α-ketoesters with bromonitromethane has been successfully developed through a domino Michael-addition/intramolecular-alkylation strategy. Acceptable yields (up to 89%) and enantioselectivities (up to 96% ee) have been obtained.


Asunto(s)
Ciclopropanos/química , Etano/análogos & derivados , Nitrocompuestos/química , Alquilación , Catálisis , Cristalografía por Rayos X , Ciclización , Ciclopropanos/síntesis química , Ésteres , Etano/química , Conformación Molecular , Estereoisomerismo
8.
Chem Commun (Camb) ; 47(17): 5034-6, 2011 May 07.
Artículo en Inglés | MEDLINE | ID: mdl-21431222

RESUMEN

A novel type of bidentate hydrogen bond donor catalysts based on (thio)phosphorodiamides catalophore has been developed for the asymmetric Michael addition of 2-hydroxy-1,4-naphthoquione to nitroolefins, affording the corresponding adducts in high yields with excellent level of enantioselectivities (97- >99% ee).

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