Supported bifunctional thioureas as recoverable and reusable catalysts for enantioselective nitro-Michael reactions
作者:José M Andrés、Miriam Ceballos、Alicia Maestro、Isabel Sanz、Rafael Pedrosa
DOI:10.3762/bjoc.12.61
日期:——
The catalytic activity of different supported bifunctional thioureas on sulfonylpolystyrene resins has been studied in the nitro-Michael addition of different nucleophiles to trans-β-nitrostyrene derivatives. The activity of the catalysts depends on the length of the tether linking the chiral thiourea to the polymer. The best results were obtained with the thiourea derived from (L)-valine and 1,6-hexanediamine. The catalysts can be used in only 2 mol % loading, and reused for at least four cycles in neat conditions. The ball milling promoted additions also worked very well.
thiourea moiety and an amino group on a chiral scaffold. Among them, thiourea 1e bearing 3,5-bis(trifluoromethyl)benzene and dimethylamino groups was revealed to be highly efficient for the asymmetric Michael reaction of 1,3-dicarbonyl compounds to nitroolefins. Furthermore, we have developed a new syntheticroute for (R)-(-)-baclofen and a chiralquaternarycarboncenter with high enantioselectivity by Michael
我们在手性支架上合成了一类带有硫脲部分和氨基的新型双功能催化剂。其中,带有 3,5-双(三氟甲基)苯和二甲氨基的硫脲 1e 被证明对于 1,3-二羰基化合物到硝基烯烃的不对称迈克尔反应非常有效。此外,我们通过迈克尔反应开发了 (R)-(-)-巴氯芬和具有高对映选择性的手性季碳中心的新合成路线。在这些反应中,我们假设催化剂的硫脲部分和氨基分别活化硝基烯烃和 1,3-二羰基化合物,以提供具有高对映选择性和非对映选择性的迈克尔加合物。
Novel bifunctional sulfonamides catalyze an enantioselective conjugate addition
作者:Patrick G. McGarraugh、Stacey E. Brenner
DOI:10.1016/j.tet.2008.11.027
日期:2009.1
A new bifunctional organocatalyst with a novel structural and functional motif has been developed. This bifunctionalsulfonamide organocatalyst was used in the conjugateaddition of 1,3-dicarbonyl compounds (13) to β-nitrostyrenes (12). Yields up to 91% and enantiomeric excesses up to 79% were obtained in this reaction. This catalyst activates both 13 via its basic moiety and 12 through hydrogen bonding
Solvent-free organocatalytic Michael addition of diethyl malonate to nitroalkenes: the practical synthesis of Pregabalin and γ-nitrobutyric acid derivatives
作者:Jin-ming Liu、Xin Wang、Ze-mei Ge、Qi Sun、Tie-ming Cheng、Run-tao Li
DOI:10.1016/j.tet.2010.11.053
日期:2011.1
enantioselective synthesis of Pregabalin 1 hydrochloride with good overall yield (44%) and enantioselectivity (98% ee) was described. The key step is an asymmetric Michael addition of equivalent of diethylmalonate and nitroalkene under solvent-free conditions using thiourea 2 as catalyst. The reaction can be applied to a variety of aromatic and aliphatic substituted nitroalkenes affording corresponding
Development of a Catalytic Enantioselective Conjugate Addition of 1,3-Dicarbonyl Compounds to Nitroalkenes for the Synthesis of Endothelin-A Antagonist <b>ABT-546</b>. Scope, Mechanism, and Further Application to the Synthesis of the Antidepressant Rolipram
作者:David M. Barnes、Jianguo Ji、Michael G. Fickes、Michael A. Fitzgerald、Steven A. King、Howard E. Morton、Frederick A. Plagge、Margo Preskill、Seble H. Wagaw、Steven J. Wittenberger、Ji Zhang
DOI:10.1021/ja026788y
日期:2002.11.1
The enantioselectivesynthesis of endothelin-A antagonist ABT-546 has been accomplished via the discovery and development of a highly selective catalyticasymmetricconjugateaddition of ketoesters to nitroolefins. Employing just 4 mol % bis(oxazoline)-Mg(OTf)(2) complex with an amine cocatalyst, we obtained the product nitroketone with 88% selectivity at the aryl-bearing stereocenter and in good yield