1889-71-0Relevant academic research and scientific papers
An electric field-induced change in the selectivity of a metal oxide-catalyzed epoxide rearrangement
Gorin, Craig F.,Beh, Eugene S.,Kanan, Matthew W.
, p. 186 - 189 (2012)
The rearrangement of cis-stilbene oxide catalyzed by Al2O 3 was studied in the presence of interfacial electric fields. Thin films of Al2O3 deposited on Si electrodes were used as the opposing walls of a reaction vessel. Application of a voltage across the electrodes engendered electrochemical double layer formation at the Al 2O3-solution interface. The aldehyde to ketone product ratio of the rearrangement was increased by up to a factor of 63 as the magnitude of the double layer charge density was increased. The results support a field-dipole effect on the selectivity of the catalytic reaction.
Electrochemical oxidation-induced benzyl C–H carbonylation for the synthesis of aromatic α-diketones
Tan, Yu-Fang,Chen, Yuan,Li, Rui-Xue,Guan, Zhi,He, Yan-Hong
supporting information, (2021/12/21)
Electrochemical oxidation-induced direct carbonylation of benzyl C–H bond for the synthesis of aromatic α-diketones is described. In this process, tetrabutylammonium iodide (nBu4NI) not only acts as an electrolyte, but its iodine anion is oxidized to an iodine radical at the anode, acting as a hydrogen atom transfer agent. The iodine radical extracts the benzyl hydrogen atom and causes the carbonylation of the benzyl position, where O2 in the air is used as an oxygen source.
H2O2-mediated room temperature synthesis of 2-arylacetophenones from arylhydrazines and vinyl azides in water
Luo, Mengqiang,Zhang, Yaohong,Fang, Ping,Li, Yan,Qi, Chenze,Li, Yong,Shen, Runpu,Cheng, Kai,Wang, Hai
supporting information, p. 630 - 635 (2022/02/01)
An environmentally benign, cost-efficient and practical methodology for the room temperature synthesis of 2-arylacetophenones in water has been discovered. The facile and efficient transformation involves the oxidative radical addition of arylhydrazines with α-aryl vinyl azides in the presence of H2O2 (as a radical initiator) and PEG-800 (as a phase-transfer catalyst). From the viewpoint of green chemistry and organic synthesis, the present protocol is of great significance because of using cheap, non-toxic and readily available starting materials and reagents as well as amenability to gram-scale synthesis, which provides an attractive strategy to access 2-arylacetophenones.
Iron-Catalyzed Enantioselective Radical Carboazidation and Diazidation of α,β-Unsaturated Carbonyl Compounds
Dong, Shunxi,Feng, Xiaoming,He, Jun,Liu, Wen,Liu, Xiaohua,Pu, Maoping,Wu, Yun-Dong,Zhang, Tinghui
, p. 11856 - 11863 (2021/08/16)
Azidation of alkenes is an efficient protocol to synthesize organic azides which are important structural motifs in organic synthesis. Enantioselective radical azidation, as a useful strategy to install a C-N3 bond, remains challenging due to the inherently instability and unique structure of radicals. Here, we disclose an efficient enantioselective radical carboazidation and diazidation of α,β-unsaturated ketones and amides catalyzed by chiral N,N′-dioxide/Fe(OTf)2 complexes. An array of substituted alkenes was transformed to the corresponding α-azido carbonyl derivatives in good to excellent enantioselectivities, benefiting the preparation of chiral α-amino ketones, vicinal amino alcohols, and vicinal diamines. Control experiments and mechanistic studies proved the radical pathway in the reaction process. The DFT calculations showed that the azido transferred to the radical intermediate via an intramolecular five-membered transition state with the internal nitrogen of the Fe-N3 species.
Copper-Catalyzed Three-Component Carboboronation of Allenes Using Highly Strained Cyclic Ketimines as Electrophiles
Deng, Hao,Dong, Yujie,Shangguan, Yu,Yang, Fazhou,Han, Sheng,Wu, Jiaqi,Liang, Bo,Guo, Hongchao,Zhang, Cheng
supporting information, p. 4431 - 4435 (2021/05/26)
A diastereoselective copper and NHC-ligand-catalyzed three-component difunctionalization of allenes with bis(pinacolato)diboron and 2H-azirines to afford borylated allylaziridines is described. The reaction exhibits complete diastereoselectivity and good yields, and the further chlorination of the corresponding borylated products was also performed. It is believed that the high ring-strain force of 2H-azirines facilitates the reaction. More chemical transformations of borylated allylaziridines are also reported.
Palladium-catalyzed synthesis of α-aryl acetophenones from styryl ethers and aryl diazonium saltsviaregioselective Heck arylation at room temperature
Kandasamy, Jeyakumar,Lee, Yong Rok,Singh, Adesh Kumar,Venkatesh, Rapelly
, p. 7832 - 7837 (2021/09/28)
Preparation of α-aryl acetophenones from styryl ethers and aryldiazonium salts is described. The reaction is catalyzed by palladium acetate at room temperature in the absence of ligand and base. The developed method is highly attractive in terms of reaction conditions, substrate scope, functional group tolerance and yields. Synthetic applications of the present method are demonstrated by preparing α-aryl indoles and 3-aryl isocoumarin from styryl ethers.
Versatile and base-free copper-catalyzed α-arylations of aromatic ketones using diaryliodonium salts
Bouquin, Maxime,Jaroschik, Florian,Taillefer, Marc
, (2021/06/11)
A ligand and base-free copper catalyzed synthetic method for the efficient α-arylation of aromatic ketones is described. In order to avoid strong bases, ketone-derived silyl enol ethers were employed. Their reaction with diaryliodonium salts as aryl source provided the intermolecular C–C coupling displaying good functional group tolerance and requiring low catalyst loading.
Benzylic Aroylation of Toluenes Mediated by a LiN(SiMe3)2/Cs+System
Dai, Ziteng,Gu, Yuanyun,Li, Jie,Mao, Jianyou,Walsh, Patrick J.,Wang, Yan-En,Xiong, Dan,Yuan, Yaqi,Zhang, Zhen
supporting information, (2022/01/14)
Chemoselective deprotonative functionalization of benzylic C-H bonds is challenging, because the arene ring contains multiple aromatic C(sp2)-H bonds, which can be competitively deprotonated and lead to selectivity issues. Recently it was found that bimetallic [MN(SiMe3)2 M = Li, Na]/Cs+ combinations exhibit excellent benzylic selectivity. Herein, is reported the first deprotonative addition of toluenes to Weinreb amides mediated by LiN(SiMe3)2/CsF for the synthesis of a diverse array of 2-arylacetophenones. Surprisingly, simple methyl benzoates also react with toluenes under similar conditions to form 2-arylacetophenones without double addition to give tertiary alcohol products. This finding greatly increases the practicality and impact of this chemistry. Some challenging substrates with respect to benzylic deprotonations, such as fluoro and methoxy substituted toluenes, are selectively transformed to 2-aryl acetophenones. The value of benzylic deprotonation of 3-fluorotoluene is demonstrated by the synthesis of a key intermediate in the preparation of Polmacoxib.
Ruthenium(II)-Catalyzed Cross-Coupling of Benzoyl Formic Acids with Toluenes: Synthesis of 2-Phenylacetophenones
Chen, Yujie,Dai, Chenyang,Huang, Zhibin,Jiang, Yaqiqi,Shu, Sai,Yang, Shan,Zhao, Yingsheng
, p. 2955 - 2961 (2021/07/22)
Herein, we report a direct method to synthesize 2-phenylacetophenone through a ruthenium(II)-catalyzed cross-coupling reaction between acyl and benzyl radical. The various derivatives of 2-phenylacetophenone were prepared easily in moderate to good yields. These reactions provide a straightforward pathway to synthesize a variety of ketones bearing various functional groups.
C-H Alkylation of Aldehydes by Merging TBADT Hydrogen Atom Transfer with Nickel Catalysis
Murugesan, Vetrivelan,Ganguly, Anirban,Karthika, Ardra,Rasappan, Ramesh
, p. 5389 - 5393 (2021/07/21)
Catalyst controlled site-selective C-H functionalization is a challenging but powerful tool in organic synthesis. Polarity-matched and sterically controlled hydrogen atom transfer (HAT) provides an excellent opportunity for site-selective functionalization. As such, the dual Ni/photoredox system was successfully employed to generate acyl radicals from aldehydes via selective formyl C-H activation and subsequently cross-coupled to generate ketones, a ubiquitous structural motif present in the vast majority of natural and bioactive molecules. However, only a handful of examples that are constrained to the use of aryl halides are developed. Given the wide availability of amines, we developed a cross-coupling reaction via C-N bond cleavage using the economic nickel and TBADT catalyst for the first time. A range of alkyl and aryl aldehydes were cross-coupled with benzylic and allylic pyridinium salts to afford ketones with a broad spectrum of functional group tolerance. High regioselectivity toward formyl C-H bonds even in the presence of α-methylene carbonyl or α-amino/oxy methylene was obtained.
