Asymmetric organocatalytic α-amination of 2-oxindoles with bis(2, 2, 2-trichloroethyl)azo-dicarboxylate. Issue 26 (27th June 2018)

• Record Type: Journal Article
• Authors: Bondanza, Mattia; Pescitelli, Gennaro; Mandoli, Alessandro
• Is Part Of: Tetrahedron letters. Volume 59:Issue 26(2018)
• Page Start: 2590
• Page End: 2594
• Publication Date: 2018-06-27
• Subjects: 2-Oxindoles -- Asymmetric organocatalysis -- Azo-dicarboxylates -- Troc protective group -- Cinchona alkaloids; Chemistry, Organic -- Periodicals; 547.005
• DOI: 10.1016/j.tetlet.2018.05.063
• Languages: English
• ISSNs: 0040-4039

Abstract

Graphical abstract: Highlights: Commercial Cinchona alkaloid organocatalysts. Fast and quantitative amination reactions. Up to 77% ee around room temperature. Easy product elaboration into 3-amino-2-oxindole derivatives. Abstract: An enantioselective electrophilic amination of 3-substituted-2-oxindoles is reported, using bis(2, 2, 2-trichloroethyl)azo-dicarboxylate and commercially available Cinchona alkaloid organocatalysts. The best results were obtained in the reaction of 3-aryl substrates, with high to excellent yields (75% to quantitative) and good stereoselectivity (64–77% ee ). Facile reductive conversion of the protected 3-hydrazino fragment into the corresponding primary amine was also demonstrated, to expand the synthetic flexibility of asymmetric electrophilic amination with azo-dicarboxylic esters en route to enantioenriched 3-amino-2-oxindoles. The absolute configuration of 3-amino-3-phenyl-2-oxindole was independently established by electronic circular dichroism (ECD), combined with time-dependent density functional theory (TDDFT).