BINOL-phosphoric acid catalyzed asymmetric Mannich addition of β-ketoesters to indolenines generated in situ by DDQ. Issue 44 (1st November 2019)

• Record Type: Journal Article
• Authors: Ramesh, Boora; Kumar, G. Ravi; Yarlagadda, Suresh; Sridhar, B.; Reddy, B.V. Subba
• Is Part Of: Tetrahedron. Volume 75:Issue 44(2019)
• Publication Date: 2019-11-01
• Subjects: Asymmetric synthesis -- Mannich reaction -- 3-indolinone-2-carboxylates -- BINOL-phosphoric acid -- β-ketoesters -- DDQ; Chemistry, Organic -- Periodicals; 547.005
• DOI: 10.1016/j.tet.2019.130620
• Languages: English
• ISSNs: 0040-4020

Abstract

Abstract: An asymmetric Mannich addition of β-ketoesters to indolenines that were generated in situ from 3-indolinone-2-carboxylates by DDQ has been developed using a catalytic amount of chiral BINOL-phosphoric acid. The corresponding chiral 3-indolinone-2-carboxylate derivatives were obtained in good yields with excellent ee (up to 99%). This is the first report on the enantioselective addition of β-ketoesters to indolenines using a chiral Brønsted acid. Graphical abstract: Image 1 Highlights: The manuscript describes an organo catalytic asymmetric Mannich reaction of β-ketoesters with indolenines. This is the first report on the enantioselective addition of β-ketoesters to indolenines This method is highly enantio selective leading to a chiral quaternary center. This method works with different β-ketoesters and 3-indolinone-2-carboxylates This approach is useful for the synthesis of chiral indolinone conjugates of ketoesters.