affords operational anion-π catalysts. According to an enolate chemistry benchmark reaction, anion-πcatalysis next to peptides occurs with record chemoselectivity but weak enantioselectivity. Catalytic activity drops with increasing distance of the amine base to the NDI surface, looser homocysteine bridges, mismatched, shortened and elongated α-helix turns, and acyclic peptide controls. Elongation of isolated
charge-delocalized enolate tautomers by anion-π interactions. Enolate-π interactions on fullerenes are much shorter than standard π-π interactions and anion-π interactions on planar surfaces, and alternative cation-π interactions are not observed. These findings open new perspectives with regard to anion-π interactions in general and the use of carbon allotropes in catalysis.
anion‐π catalysis is to stabilize anionic transitionstates by anion‐π interactions on aromatic surfaces. For asymmetric anion‐π catalysis, π‐acidic surfaces have been surrounded with stereogenic centers. This manuscript introduces the first anion‐π catalysts that operate with axial chirality. Bifunctional catalysts with tertiary amine bases next to π‐acidic naphthalenediimide planes are equipped with
Organocatalytic Enantioselective Michael-Addition of Malonic Acid Half-Thioesters to β-Nitroolefins: From Mimicry of Polyketide Synthases to Scalable Synthesis of γ-Amino Acids
作者:Han Yong Bae、Surajit Some、Jae Heon Lee、Ju-Young Kim、Myoung Jong Song、Sungyul Lee、Yong Jian Zhang、Choong Eui Song
DOI:10.1002/adsc.201100458
日期:2011.11
Highly enantioselective biomimetic Michael addition reactions of malonicacid half thioesters (MAHTs) to a variety of nitroolefins, affording the optically active γ-amino acid precursors, were developed by employing the Cinchona-based squaramides (up to >99% ee). Remarkably, this biomimetic process is enantioconvergent, a highly desirable feature of a catalytic asymmetric reaction, whereby E/Z-isomers