Dinuclear Zinc Catalyzed Asymmetric Spirannulation Reaction: An Umpolung Strategy for Formation of α-Alkylated-α-Hydroxyoxindoles
作者:Barry M. Trost、Keiichi Hirano
DOI:10.1021/ol300577y
日期:2012.5.18
A highlydiastereo- and enantioselective formal [3 + 2] cycloaddition of α,β-unsaturated esters and 3-hydroxyoxindoles catalyzed by a dinuclear zinc-ProPhenol complex is reported. The stereoselective Michaeladditions of 3-hydroxyoxindoles and the subsequent transesterifications afford spirocyclic δ-lactones.
Dioxindole in Asymmetric Catalytic Synthesis: Routes to Enantioenriched 3-Substituted 3-Hydroxyoxindoles and the Preparation of Maremycin A
作者:Giulia Bergonzini、Paolo Melchiorre
DOI:10.1002/anie.201107443
日期:2012.1.23
nucleophilicity of dioxindole under different reaction conditions is key to a direct and easy access to valuable spiro oxindole γ butyrolactones and 3‐substituted 3‐hydroxyoxindole derivatives in excellent yields and enantioselectivities (see scheme). The preparation of maremycin A serves as an example for the potential usefulness of this previously unexplored reactivity in natural product synthesis.
activation of saturated acid chlorides by oxidative N-heterocycliccarbene catalysis has been successfully utilized to synthesize enantio-enriched spirooxindolelactones and δ-lactones. The reaction involves the transformation of the β sp3 carbon of saturated acid chlorides into an electrophilic carbon as a key step. The product was obtained in excellent yield and stereoselectivity.
Organocatalytic Asymmetric Michael/Cyclization Cascade Reactions of 3-Hydroxyoxindoles/3-Aminooxindoles with α,β-Unsaturated Acyl Phosphonates for the Construction of Spirocyclic Oxindole-γ-lactones/lactams
Enantioselective Michael/cyclization cascade reactions of 3-hydroxyoxindoles/3-aminooxindoles with α,β-unsaturatedacyl phosphonates by using a cinchonine derived squaramide as the catalyst were developed. A broad range of spirocyclic oxindole-γ-lactones/lactams could be obtained in moderate to excellent yields (up to 98%) with good to excellent diastereo- and enantioselectivities (up to >99:1 dr and
An N-Heterocyclic Carbene/Lewis Acid Strategy for the Stereoselective Synthesis of Spirooxindole Lactones
作者:Julien Dugal-Tessier、Elizabeth A. O'Bryan、Thomas B. H. Schroeder、Daniel T. Cohen、Karl A. Scheidt
DOI:10.1002/anie.201201643
日期:2012.5.14
cooperative catalysis approach for the enantioselective formal [3+2] addition of α,β‐unsaturated aldehydes to isatins has been developed. Homoenolate annulations of β‐aryl enals catalyzed by an N‐heterocycliccarbene (NHC) require the addition of lithium chloride for high levels of enantioselectivity. This NHC‐catalyzed annulation has been used for the total synthesis of maremycin B.
α,β-不饱和醛与靛红的对映选择性正式[3+2]加成协同催化方法已被开发。由 N-杂环卡宾 (NHC) 催化的 β-芳基烯醛的均烯化环需要添加氯化锂以获得高水平的对映选择性。这种 NHC 催化的环化已用于马雷霉素 B 的全合成。