通过将分子间的阿道尔顿缩合反应与随后的分子内碱基促进的均相芳族取代反应相结合,已经实现了一种不寻常的苯环化反应。这种新颖的级联反应为在DMSO中存在Cs 2 CO 3的情况下从2-卤代苯甲醛和吲哚-2-酮的各种萘稠合的吲哚提供了直接的方法。吲哚-2-酮作为新的和内部的电子供体的烯醇被证明可以引发分子内自由基脱卤偶联。
Catalyst-Free One-Pot Tandem Reduction of Oxo and Ene/Yne Functionalities by Hydrazine: Synthesis of Substituted Oxindoles from Isatins
作者:Mukund Jha、Ganesh M. Shelke、Anil Kumar
DOI:10.1002/ejoc.201402038
日期:2014.6
An unprecedented one-pottandemreduction of oxo and ene/ynefunctionalities of substitutedisatins is disclosed for the synthesis of oxindole derivatives in excellent yields. The reaction is simply performed by treating N-(2-alkenyl)/propargylisatins with an excess amount of hydrazine hydrate (25 %) under catalyst-free refluxing conditions. The reduction process appears to be quite unique and proceeds
base-promoted homolytic aromatic substitution. This novel cascade reaction provides a straightforward approach toward various naphtho-fused oxindoles from 2-halobenzaldehydes and indolin-2-ones in the presence of Cs2CO3 in DMSO. The enolates of indolin-2-ones as new and internal electron donors have been demonstrated to initiate intramolecular radical dehalogenative coupling.
通过将分子间的阿道尔顿缩合反应与随后的分子内碱基促进的均相芳族取代反应相结合,已经实现了一种不寻常的苯环化反应。这种新颖的级联反应为在DMSO中存在Cs 2 CO 3的情况下从2-卤代苯甲醛和吲哚-2-酮的各种萘稠合的吲哚提供了直接的方法。吲哚-2-酮作为新的和内部的电子供体的烯醇被证明可以引发分子内自由基脱卤偶联。