N-Heterocyclic carbene-catalyzed oxidative [3 + 2] annulation of dioxindoles and enals: cross coupling of homoenolate and enolate
作者:Xiang-Yu Chen、Kun-Quan Chen、De-Qun Sun、Song Ye
DOI:10.1039/c6sc04135c
日期:——
The N-heterocycliccarbene-catalyzed oxidative [3 + 2] annulation of dioxindole and enals was developed, giving the corresponding spirocyclic oxindole-γ-lactones in good yields with high to excellent diastereo- and enantioselectivities. The challenging aliphatic enals worked effectively using this strategy. The oxidative cross coupling of homoenolate and enolate via single electron transfer was proposed
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.
The asymmetric Michael addition of dioxindoles to β-substituted nitroalkenes is reported. The bifunctional primary amine-thiourea A, by means of a non-covalent-based mode of catalysis, secures direct access to 3-substituted 3-hydroxyoxindole derivatives with high stereocontrol.
报告了二氧吲哚与 β-取代的硝基烯的不对称迈克尔加成反应。双功能伯胺-硫脲 A 通过非共价催化模式,可直接获得具有高度立体控制性的 3-取代 3-羟基吲哚衍生物。
Kohn; Ostersetzer, Monatshefte fur Chemie, 1916, vol. 37, p. 26
作者:Kohn、Ostersetzer
DOI:——
日期:——
Reaction of isatin with alkylating agents with acidic methylenes
作者:María S. Shmidt、Isabel A. Perillo、Mercedes González、María M. Blanco
DOI:10.1016/j.tetlet.2012.03.010
日期:2012.5
The reaction of isatin (1) with different alkyl halides 2 and alkaline carbonates in aprotic polar solvents leads mainly to N-alkyl derivatives 3. The use of alkylating agents that have acidic methylenes leads to competitive formation of the corresponding epoxide 5. The formation of 5 is favored by low-polarity solvents at low temperatures and strong bases. Epoxides 5c, d obtained using NaEtOH/EtOH at 0-5 degrees C are transformed into the corresponding 4-quinolinones 6 at higher temperatures. The use of Ag2CO3 allows obtaining compounds 3 as major products, along with varying amounts of labile O-alkyl derivatives 4 and dimerization products. (C) 2012 Elsevier Ltd. All rights reserved.