New Method for Preparation of Coumarins and Quinolinones via Pd-Catalyzed Intramolecular Hydroarylation of C−C Triple Bonds
摘要:
A new and general method has been developed for preparation of coumarins and quinolinones by intramolecular hydroarylation of alkynes. Various aryl alkynoates and alkynanilides undergo fast intramolecular reaction at room temperature in the presence of a catalytic amount of Pd(OAc)(2) in a mixed solvent containing trifluoroacetic acid (TFA), affording coumarins and quinolinones in moderate to excellent yields with more than 1000 turnover numbers (TON) to Pd. The methodology proved to tolerate a number of functional groups such as Br and CHO. On the basis of isotope experiments, a possible mechanism involving ethynyl chelation-assisted electrophilic metalation of aromatic C-H bonds by in-situ generated cationic Pd(II) species has been discussed. Also the involvement of vinylcationic species has been suggested.
Palladium-Catalyzed Direct Annulation of Benzoic Acids with Phenols to Synthesize Dibenzopyranones
作者:Yang Wang、Jie-Yu Gu、Zhang-Jie Shi
DOI:10.1021/acs.orglett.7b00177
日期:2017.3.17
Direct annulation of benzoic acids with phenols via palladium-catalyzed oxidative coupling is reported. Readily available and inexpensive starting materials were used in this novel method to synthesize highly valuable and useful dibenzopyranone scaffolds. Broad substrate scope and simple operation make this method potentially practical. Preliminary mechanistic studies were conducted to understand this
One-pot catalysis of dehydrogenation of cyclohexanones to phenols and oxidative Heck coupling: expedient synthesis of coumarins
作者:Donghee Kim、Minsik Min、Sungwoo Hong
DOI:10.1039/c3cc41296b
日期:——
One-pot reactions leading to highly functionalized coumarins have been developed via a Pd(II)-catalyzed dehydrogenation-oxidative Heck-cyclization process.
通过Pd(II)催化的脱氢-氧化Heck环化过程已经开发出了导致高度功能化香豆素的一锅法反应。
Stereo- and Regioselective Addition of Arene to Alkyne Using Abnormal NHC Based Palladium Catalysts: Elucidating the Role of Trifluoroacetic Acid in Fujiwara Process
作者:Pradip Kumar Hota、Anex Jose、Swadhin K. Mandal
DOI:10.1021/acs.organomet.7b00649
日期:2017.11.27
(aNHC) based Pd catalysts have been used for the efficient hydroarylation of aromatic C–H bonds leading to new C–C bond formation through regio- and stereoselective addition to alkynes. The addition reaction has been realized by a catalytic amount of Pd (II) compound (0.5 mol %) in trifluoroacetic acid (TFA) under ambient conditions. Various arenes undergo transhydroarylation selectively across the triple
Amine-Catalyzed Cascade Synthesis of 3,4-Diunsubstituted Coumarins
作者:Jia Wei、Pengcheng Wang、Qianfa Jia、Jiaoyao Huang、Zhiyun Du、Kun Zhang、Jian Wang
DOI:10.1002/ejoc.201300538
日期:2013.7
We disclose an efficient route to synthesize 3,4-diunsubstitutedcoumarins through a cascade organocatalytic reaction. The reaction is catalyzed by using of a combination of benzylamine (10 mol-%) and triethylamine (10 mol-%). Various salicylaldehydes were tested, and the corresponding coumarin products were obtained in good to high yields under mild and metal-free reaction conditions.
Palladacycles bearing COOH-/ester-functionalized N-heterocyclic carbenes: Divergent syntheses and catalytic applications
作者:Yanyan Hu、Shuai Guo
DOI:10.1002/aoc.4703
日期:2019.3
Two new [C^N]‐type palladacyclic dinuclearcomplexes bearing carboxylate‐containing N‐heterocyclic carbenes (NHCs) were synthesized, and in both cases the carboxylato‐NHC ligand adopts a bridging mode. Both complexes proved to be suitable precursors, which can be used to divergently access palladacycles bearing ester‐ or COOH‐functionalized NHCs upon esterification or acidolysis. In the esterification