Synthesis of 3,3′-Spirocyclic Oxindoles via Phosphine Catalyzed [4 + 2] Cyclizations
摘要:
Triphenylphosphine promoted reactions between 3-arylideneoxindoles and (delta-aryl-substituted penta-2,3-dienoates afford an unprecedented access to spirocyclic oxindoles with functionalized six-membered rings. In these new [4 + 2] cyclization processes, the allenoates operate as the four-carbon synthons, thanks to the involvement of the substituted (delta-carbons. These reactions give excellent control of the relative stereochemistry of the three stereogenic centers. The stereochemistry of the final product has been ascertained by X-ray diffraction studies.
Phosphine-catalyzed [4 + 2] annulation of γ-benzyl allenoates: facile synthesis of benzothieno[3,2-<i>b</i>]pyran derivatives
作者:Shanshan Ma、Aimin Yu、Xiangtai Meng
DOI:10.1039/c8ob00004b
日期:——
domino reaction between γ-benzyl allenoates and ethyl (Z)-2-(3-oxobenzo[b]thiophen-2(3H)-ylidene)acetate has been developed, which produces a series of 2H-benzo[4,5]thieno[3,2-b]pyran derivatives in high yields. The substrate scope includes both electron-withdrawing (e.g., halogen) and electron-donating (e.g., methoxy) groups on both the benzothiophene and allenoate moieties. The reaction can also be
已开发出一种有效的三(4-甲氧基苯基)膦催化γ-苄基脲基酸酯与(Z)-2-(3-氧代苯并[ b ]噻吩-2(3H)-亚烷基)乙酸乙酯之间的多米诺反应,其产生一系列高产率的2 H-苯并[4,5]噻吩并[3,2- b ]吡喃衍生物。底物范围包括在苯并噻吩和脲基酸酯部分上的吸电子基团(例如卤素)和供电子基团(例如甲氧基)。该反应也可以以克为单位进行,并且收率很高(例如,占77%)。在该反应中,γ-取代的脲基甲酸酯起着两个碳的合成子的作用,其方式迄今在文献中很少报道。
Bifunctional-Phosphine-Catalyzed Sequential Annulations of Allenoates and Ketimines: Construction of Functionalized Poly-heterocycle Rings
A highlystereoselective sequential annulation reaction between γ‐substituted allenoates and ketimines was reported. By using bifunctional N‐acyl aminophosphine catalysts, poly‐heterocycle rings were obtained with high stereocontrol in good to excellent yields. The desired products have four contiguous stereogeniccenters (one quaternary and three tertiary carbon centers), and only one isomer was obtained
and commercially available starting materials in five chemical operations (totally 4.16g scale), are introduced. To our delight, the JiaPhos catalysts display good performance in enantioselective (4 + 2) annulations involving 3-methylene-2-oxindoles and γ-benzyl allenoates, providing a wide range of 3,3′-spirocyclic oxindoles with good efficiency and enantioselectivity.