Supported and Unsupported Chiral Squaramides as Organocatalysts for Stereoselective Michael Additions: Synthesis of Enantiopure Chromenes and Spirochromanes
作者:José M. Andrés、Jorge Losada、Alicia Maestro、Patricia Rodríguez-Ferrer、Rafael Pedrosa
DOI:10.1021/acs.joc.7b01177
日期:2017.8.18
Novel supported chiral bifunctional squaramides have been easily prepared starting from diamines derivedfrom natural amino acids and commercially available aminoalkyl polystyrene resins. These squaramides behave as excellent stereoselective recoverable organocatalysts in different Michael additions, in neat conditions at room temperature. The reaction on 2-(2-nitrovinyl) phenol as electrophile lead
Organocatalytic enantioselective Michael addition of β-diketones to β-nitrostyrene: the first Michael addition of dipivaloylmethane to an activated olefin.
作者:Declan P. Gavin、John C. Stephens
DOI:10.3998/ark.5550190.0012.930
日期:——
The addition of a family of β-diketones to β-nitrostyrene was explored using a library of cinchona organocatalysts. A thiourea organocatalyst, under improved reaction conditions, is shown to be much more efficient at catalyzing this reaction than previously reported giving excellent yields and enantioselectivites (up to 95% yield and 97% ee). The same thiourea organocatalyst was employed in the first
Synthesis of Chiral Tertiary Amine–Thioureas Based on Spirobiindane and Application in Catalytic Asymmetric Michael Addition Reaction
作者:Zhao Han、Xufeng Lin
DOI:10.1055/s-0039-1691643
日期:2020.4
A series of novel chiral bifunctional tertiary amine–thioureas based on spirobiindane were designed and synthesized as organocatalysts. One of these catalysts was shown to promote the asymmetric Michael addition reaction of 1,3-diphenylpropane-1,3-dione to nitroolefins, affording the desired products in good yields (up to 95%) and enantioselectivities (up to 98% ee).
A Polystyrene-Supported, Highly Recyclable Squaramide Organocatalyst for the Enantioselective Michael Addition of 1,3-Dicarbonyl Compounds to β-Nitrostyrenes
作者:Pinar Kasaplar、Paola Riente、Caroline Hartmann、Miquel A. Pericàs
DOI:10.1002/adsc.201200526
日期:2012.11.12
A chiral squaramide has been supported onto a polystyrene (PS) resin through a copper-catalyzed azide–alkyne cycloaddition (CuAAC) reaction and used as a very active, easily recoverable and highly reusable organocatalyst for the asymmetric Michaeladdition of 1,3-dicarbonylcompounds to β-nitrostyrenes. The PS-supported squaramide could be recycled up to 10 times.
Molecular Engineering of β‐Substituted Oxoporphyrinogens for Hydrogen‐Bond Donor Catalysis
作者:Mandeep K. Chahal、Daniel T. Payne、Yoshitaka Matsushita、Jan Labuta、Katsuhiko Ariga、Jonathan P. Hill
DOI:10.1002/ejoc.201901706
日期:2020.1.9
Beta functionalization of oxoporphyrinogens as H‐bonddonor catalysts with binding site designed for dual activation of substrates is reported. Introduction of the β‐substituents enables the catalysis of 1,4‐conjugate additions, sulfa‐Michael additions and Henry/aza‐Henry reactions at low catalyst loadings (≤ 1 mol‐%) under mild conditions.