Low-Temperature, Transition-Metal-Free Cross-Dehydrogenative Coupling Protocol for the Synthesis of 3,3-Disubstituted Oxindoles
作者:James R. Donald、Richard J. K. Taylor、Wade F. Petersen
DOI:10.1021/acs.joc.7b02085
日期:2017.10.20
strong, nonreversible base in these reactions has been found to effect a dramatic drop in reaction temperature (to room temperature) relative to the current state-of-the-art (>100 °C) procedure. When employing iodine as an “oxidant”, new evidence suggests that this transformation may occur via a transiently stable iodinated intermediate rather than by direct single-electron oxidation.
2-Electron-withdrawing-group-substituted 2-bromoanilides can be converted to the corresponding 3,3-disubstituted oxindoles with high efficiency under visible light irradiation by using fac-Ir(ppy)3 as the photoredox catalyst. This protocol is suitable for the synthesis of oxindoles with chloro and bromo atoms attached to the phenyl ring.
在可见光照射下,通过将2-抽电子基团取代的2-溴苯胺可以高效转化为相应的3,3-二取代的羟吲哚。 fac -Ir(ppy)3作为光氧化还原催化剂。该方案适用于合成具有连接在苯环上的氯和溴原子的羟吲哚。
First C−H Activation Route to Oxindoles using Copper Catalysis
作者:Johannes E. M. N. Klein、Alexis Perry、David S. Pugh、Richard J. K. Taylor
DOI:10.1021/ol1012668
日期:2010.8.6
The preparation of 3,3-disubstituted oxindoles by a formal C-H, Ar-H coupling of anilides is described. Highly efficient conditions have been Identified using catalytic (5 mol %) Cu(OAc)(2)center dot H(2)O with atmospheric oxygen as the reoxidant; no additional base is required, and the reaction can be run in toluene or mesitylene. Optimization studies are reported together with a scope and limitation investigation based on variation of the anilide precursors. The application of this methodology to prepare a key Intermediate for the total synthesis of the anticancer, analgesic oxindole alkaloid Horsfiline is also described.
Intramolecular Dehydrogenative Coupling Approach to 2‐Oxindoles Using Fe(OAc)
<sub>2</sub>
/NaI/Na
<sub>2</sub>
S
<sub>2</sub>
O
<sub>8</sub>
A novel method for the synthesis of 2‐oxindoles from 1,3‐dicarbonyl compounds based on ferrous salt and iodide catalyst was described. Through a new catalytic oxidation system, the intramolecular dehydrogenation coupling reaction was completed by using catalytic amount of iodine.