C2‐Symmetric Cinchona Alkaloid Derivatives: Versatile Catalysts for the Enantioselective C−C Bond Forming Conjugate Addition of Nucleophiles to Simple α, β‐Unsaturated Acyl Pyrazoles. Issue 48 (28th December 2020)

• Record Type: Journal Article
• Authors: Curran, Simon P.; Fallon, Brendan J.; Connon, Stephen J.
• Is Part Of: ChemistrySelect. Volume 5:Issue 48(2020)
• Page Start: 15190
• Page End: 15194
• Publication Date: 2020-12-28
• Subjects: pyrazoles -- conjugate addition -- organocatalysis -- γ-amino acid -- nitroesters; Chemistry -- Periodicals; 540.5
• DOI: 10.1002/slct.202004505
• Languages: English
• ISSNs: 2365-6549

Abstract

Abstract: A single C2 ‐symmetric squaramide catalyst system allows the facile addition of either malononitrile or benzyl nitroacetate to simple pyrazole‐based Michael acceptors with excellent enantiocontrol and at lower catalyst loadings than previously possible. The latter reactions are not diastereoselective, however facile hydrogenolysis leads to decarboxylation and formation of the formal adduct from the addition of nitromethane (a very recalcitrant nucleophile in this chemistry) with excellent yield and enantiocontrol. Abstract : A C2 ‐symmetric cinchona alkaloid‐based catalyst and the use of benzyl nitroacetate allows facile highly enantioselective conjugate addition reactions to α, β‐unsaturated acylpyrazoles as a surrogate for nitromethane addition