二取代的苯并[ b ]呋喃是通过二氯苯酚和末端炔的邻位选择性Sonogashira偶联反应,然后使用钯-二羟基叔苯基膦(Cy-DHTP)催化剂在一个罐中进行环化和Suzuki-Miyaura偶联反应而合成的。亚化学计量的四丁基氯化铵的使用有效地加速了Suzuki-Miyaura偶联。该方案也成功地用于从二氯苯胺衍生物的一锅法合成二取代的吲哚。
Silver(I)-Mediated CH Amination of 2-Alkenylanilines: Unique Solvent-Dependent Migratory Aptitude
作者:So Won Youn、Tae Yun Ko、Min Jung Jang、Su San Jang
DOI:10.1002/adsc.201400759
日期:2015.1.12
A highly effective silver(I)‐mediated CHamination of 2‐alkenylanilines has been developed to afford a diverse range of substituted indoles. High functional group tolerance, broad substrate scope, simple/fast/high‐yielding reaction, and recovery/reuse of the inexpensive silver oxidant are noteworthy. Furthermore, an uncommon migratory process of β‐monosubstituted 2‐alkenylanilines with solvent‐dependence
An effective metal-free C-H amination of N-Ts-2-alkenylanilines by using DDQ as an oxidant has been developed to afford a diverse range of substituted indoles. This protocol is operationally simple and robust, obviates the need of expensive transition-metal catalysts, and offers a broad substrate scope. A mechanism involving a radical cation generated by SET and a migratorial process via a phenonium ion intermediate is proposed.
Palladium-free zinc-mediated hydroamination of alkynes: efficient synthesis of indoles from 2-akynylaniline derivatives
Reaction of 2-phenylethynyl N-tosylanilide prepared by Pd-free procedure with ZnBr(2) (3 equiv) in refluxing toluene gave N-tosyl-2-phenylindole in 93% yield. Treatment of 2-phenylethynylaniline with ZnBr(2) (1 equiv) in refluxing toluene resulted in the formation of 2-phenylindole in 91% yield. Catalytic ZnBr(2) (0.05 equiv) effectively reacted with 2-alkynylanilines to afford 2-substituted indoles in high yields. Thus, complete Pd-free zinc catalyzed hydroamination of 2-alkynylanilines was achieved. (C) 2009 Elsevier Ltd. All rights reserved.
Synthesis of 3-Carboxylated Indoles through a Tandem Process Involving Cyclization of 2-Ethynylanilines Followed by CO<sub>2</sub> Fixation in the Absence of Transition Metal Catalysts
In this study, a facile synthesis of 3-carboxylated indoles involving a tandem-type cyclization of 2-ethynylanilines and subsequent CO2 fixation at the 3-position of the indole ring is realized. The reaction proceeds efficiently at 65 degrees C under 10 atm of CO2, giving rise to variously substituted 3-carboxylated indoles, generally in high yields. An inorganic base, such as K2CO3, is the only reagent required, and the addition of transition metal catalysts is not necessary. The method provides a novel, simple, and promising strategy for CO2 fixation in the research field of heterocyclic chemistry.