共查询到20条相似文献,搜索用时 503 毫秒
1.
Jianchao Liu Xiaoting Zhang Hui Peng Huanfeng Jiang Biaolin Yin 《Advanced Synthesis \u0026amp; Catalysis》2015,357(4):727-731
Copper chloride‐catalyzed aerobic oxidative annulation of N‐furfuryl‐β‐enaminones provides access to polysubstituted pyrroles and indoles. This protocol involves an unprecedented copper chloride‐catalyzed oxidative chlorination of furan and pyrrole rings with oxygen as the terminal oxidant.
2.
3.
4.
α‐Substituted β‐acetyl amides could undergo C C bond cleavage to form α‐keto amides when treated with copper(II) chloride (CuCl2) and boron trifluoride diethyl etherate (BF3⋅OEt2) under an oxygen atmosphere. The yield can be increased by the addition of tert‐butyl hydroperoxide which alone can also effect the reaction. The reaction provides a new protocol for the synthesis of α‐keto amides.
5.
Ligand‐Free Nickel‐Catalysed 1,4‐Addition of Arylboronic Acids to α,β‐Unsaturated Carbonyl Compounds
Wen Chen Lu Sun Xi Huang Jiayi Wang Yanqing Peng Gonghua Song 《Advanced Synthesis \u0026amp; Catalysis》2015,357(7):1474-1482
A simple and efficient ligand‐free nickel‐based catalytic system has been developed for the 1,4‐addition of arylboronic acids to α,β‐unsaturated carbonyl compounds. With catalyst loadings of 1–2 mol%, a series of 1,4‐adducts from chalcones and cinnamates was obtained in moderate to excellent yields within 5–30 min under a nitrogen atmosphere and microwave irradiation. The 1,4‐addition of arylboronic acids to acrylates is less efficient.
6.
Hong‐Wu Zhao Hai‐Liang Pang Ting Tian Bo Li Xiao‐Qin Chen Xiu‐Qing Song Wei Meng Zhao Yang Yue‐Yang Liu Yu‐Di Zhao 《Advanced Synthesis \u0026amp; Catalysis》2016,358(11):1826-1832
In the presence of sodium carbonate, the [4+3] cycloadditions of α‐halogeno hydrazones with nitrones were performed efficiently, and affording 2,3,4,7‐tetrahydro‐1,2,4,5‐oxatriazepines in moderate to high yields.
7.
Hai‐Bin Yang Yun‐zhou Zhao Rui Sang Yin Wei Min Shi 《Advanced Synthesis \u0026amp; Catalysis》2014,356(18):3799-3808
Hydroquinine anthraquinone‐1,4‐diyl diether [(DHQ)2AQN]‐catalyzed unprecedented asymmetric domino annulation reactions of acylidenoxindoles/isatins, acylidenoxindoles and allenoates are disclosed in this communication, providing a facile access to hexahydrofuro[2,3‐b]furans containing four contiguous chiral centers in good to excellent yields along with good to excellent ee values and moderate to good dr values. Based on theoretical investigations, a concerted [3+2] ring‐closure process was proposed, in which steric hindrance and π–π stacking interaction between catalyst and substrate subtly co‐control the diastereoselectivity of the reaction.
8.
Xiang Li Siyu Li Suyan Sun Fan Yang Weiguo Zhu Yu Zhu Yusheng Wu Yangjie Wu 《Advanced Synthesis \u0026amp; Catalysis》2016,358(10):1699-1704
An efficient and generally applicable protocol for decarboxylative coupling of α,α‐difluoroarylacetic acids with ethynylbenziodoxolone (EBX) reagents has been developed, affording α,α‐difluoromethylated alkynes bearing various functional groups in moderate to excellent yields. Remarkably, this potassium persulfate (K2S2O8)‐promoted reaction employs water as solvent under transition metal‐free conditions, thus providing a green synthetic approach to α,α‐difluoromethylated alkynes.
9.
Joanna Hejmanowska Anna Albrecht Jakub Pita ukasz Albrecht 《Advanced Synthesis \u0026amp; Catalysis》2015,357(18):3843-3848
An organocatalytic approach for the stereoselective synthesis of 3,4‐dihydrocoumarins with an α,α‐disubstituted amino acid moiety incorporated is presented. The developed methodology is based on the cascade reaction between α‐substituted azlactones and 2‐hydroxychalcones. It is initiated by a chiral Brønsted base‐catalyzed enantio‐ and diastereoselective Michael reaction followed by the azlactone ring opening to construct a 3,4‐dihydrocoumarin framework. Products bearing two adjacent stereogenic centers, one being quaternary, were formed with high enantioselectivities and excellent diastereoselectivities. Furthermore, the complete regioselectivity of the new cascade reactivity is worthy of notice.
10.
An intramolecular imination/azidation sequence has been realized through the tetrakis(acetonitrile)copper(I) hexafluorophophate [Cu(CH3CN)4PF6]‐catalyzed reaction of γ,δ‐unsaturated ketone O‐benzoyl oximes with trimethylsilyl azide (TMSN3). The reaction proceeds via the copper‐mediated N O cleavage and subsequent C N forming 5‐exo cyclization. The thus formed intermediate is then azidated to afford the corresponding dihydropyrrole product. Preliminary mechanistic investigations suggest that the cyclization step does not involve a radical intermediate.
11.
Jun Wang Zhihui Shao Kai Ding Wing Yiu Yu Albert S.C. Chan 《Advanced Synthesis \u0026amp; Catalysis》2009,351(9):1250-1254
12.
This paper describes the aerobic oxidation of styrenes catalyzed by iron(III) chloride (FeCl3) to form β‐keto‐N‐alkoxyphthalimides in fair to good yields. This oxidative process employs mild conditions with green and atom efficient dioxygen (O2) as the oxidant.
13.
Peidong Song Qing Li Congcong Wang Wenfa Wu Xu Mao Jiajia Wang Xiangdong Hu 《Advanced Synthesis \u0026amp; Catalysis》2016,358(8):1208-1212
A four‐electron electrocyclic ring‐opening/intermolecular [4+2] cycloaddition of α‐hydroxycyclobutenones is reported. The reaction represents the first example for the intermolecular cycloaddition of the extensively studied enol‐ketene intermediate, and provides a new synthetic route to multiply substituted δ‐lactams in high stereoselectivity.
14.
Shengwei Chen Qinxin Lou Yuyang Ding Shasha Zhang Wenhui Hu Junling Zhao 《Advanced Synthesis \u0026amp; Catalysis》2015,357(11):2437-2441
We have developed and optimized an enantioselective Michael reaction of malononitrile with β,β‐disubstituted nitroalkenes. This reaction was catalyzed by a cinchona alkaloid derived thiourea catalyst, producing products of high yields (up to 98 %) and stereoselectivities (up to 93 % ee). One of the adducts was used as an intermediate for the synthesis of dihydropyrrole derivative bearing a synthetically valuable quaternary chiral center.
15.
Ji Yang Yan‐Yun Liu Ren‐Jie Song Zhi‐Hong Peng Jin‐Heng Li 《Advanced Synthesis \u0026amp; Catalysis》2016,358(14):2286-2292
A new copper‐mediated synthesis of α‐sulfonylethanone oximes from styrenes, sodium arylsulfinates and tert‐butyl nitrite (t‐BuONO; TBN) is presented. This intermolecular three‐component method enables the one‐step formation of C N and C S bonds under mild conditions, and represents a new, straightforward approach to α‐sulfonylethanone oximes.
16.
Krishna Bahadur SomaiMagar Yong Rok Lee 《Advanced Synthesis \u0026amp; Catalysis》2014,356(16):3422-3432
Efficient one‐step syntheses of α,β‐ and β,β‐dihaloenones were achieved by ruthenium(II)‐catalyzed reactions between cyclic or acyclic diazodicarbonyl compounds and oxalyl chloride or oxalyl bromide in moderate to good yields. This methodology offers several significant advantages, which include ease of handling, mild reaction conditions, one‐step reaction, and the use of an effective and non‐toxic catalyst. The synthesized compounds were further transformed into highly functionalized novel molecules bearing aromatic rings on the enone moiety using the Suzuki reaction.
17.
Xiao‐Nan Zhang Gen‐Qiang Chen Xiang Dong Yin Wei Min Shi 《Advanced Synthesis \u0026amp; Catalysis》2013,355(17):3351-3357
A novel asymmetric [4+2] annulation of vinyl ketones with oxindole‐derived α,β‐unsaturated imines has been developed in the presence of a multifunctional thiourea‐phosphine catalyst derived from a natural amino acid, providing the first phosphine‐catalyzed enantioselective synthesis of 2′,3′‐dihydro‐1′H‐spiro[indoline‐3,4′‐pyridin]‐2‐ones in good yields with excellent stereoselectivities under mild conditions.
18.
Eleonora Gianolio Resmi Mohan Albrecht Berkessel 《Advanced Synthesis \u0026amp; Catalysis》2016,358(1):30-33
The dynamic kinetic resolution of α‐substituted racemic β‐lactams by alcoholytic ring‐opening, catalyzed by immobilized lipase B from Candida antarctica is described. With this process, a variety of racemic α‐substituted N‐Cbz‐azetidinones (Cbz=benzyloxycarbonyl) was transformed to the corresponding N‐Cbz‐protected β2‐amino acid allyl esters with high enantioselectivity (up to 99%) and high yields (up to quantitative) at room temperature.
19.
Cheonhyoung Park Min Woo Ha Byungsoo Kim Suckchang Hong Doyoung Kim Yohan Park Mi‐hyun Kim Jae Kyun Lee Jeeyeon Lee Hyeung‐geun Park 《Advanced Synthesis \u0026amp; Catalysis》2015,357(13):2841-2848
A new enantioselective synthetic method for the synthesis of α,α‐dialkylmalonates with a quaternary carbon center was developed via α‐alkylation of prochiral malonates by phase‐transfer catalysis (PTC). Asymmetric α‐alkylation of benzylideneamino tert‐butyl α‐methylmalonates under phase‐transfer catalytic conditions in the presence of (S,S)‐3,4,5‐trifluorophenyl‐NAS bromide afforded the corresponding α,α‐dialkylmalonates in high yields (up to 97%) with excellent enantioselectivities (up to 98% ee). The products were then selectively hydrolyzed to chiral malonic monoacids under basic, acidic, or catalytic hydrogenation conditions.
20.
Changhui Liu Li Zhou Wenbo Huang Man Wang Yanlong Gu 《Advanced Synthesis \u0026amp; Catalysis》2016,358(6):900-918
An effective method to synthesize α‐functionalized furan and pyrrole derivatives was developed using 2‐alkoxy‐2,3‐dihydrofurans as modular precursors. This protocol featured a previously unreported tandem nucleophilic substitution/heteroaromatization reaction. Nucleophiles such as indole, α‐oxoketene dithioacetal, trimethoxybenzene, and dimethoxynaphthalene can react readily with 2‐alkoxy‐2,3‐dihydrofurans to afford α‐functionalized five‐membered ring heterocycles in the presence of acid catalysts, such as copper bromide and iron chloride. The mechanism of the reaction was also discussed, in which the first step, nucleophilic substitution, is the key in triggering the succeeding heteroaromatization. This method can also be extended to the synthesis of dihydrothiophenes.