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排序方式: 共有455条查询结果,搜索用时 31 毫秒
1.
A novel, rational‐designed approach to access various heteroaryl‐substituted alkyl thioethers was developed via docking‐migration cascade process. By utilizing three components involving alkene, dual‐function reagent, and thioetherificating reagent, radical heteroarylalkylation of alkenes followed by thiolation of the alkyl radical intermediates proceeded smoothly, manifesting well compatibility of substrates and cascade transformations. Furthermore, this protocol also features mild conditions, broad substrate scope, and wide product diversity. 相似文献
2.
Gunasekaran Balamurugan Sundarraman Balaji Rengan Ramesh Nattamai S.P. Bhuvanesh 《应用有机金属化学》2019,33(1)
A panel of six new arene Ru (II)‐NHC complexes 2a‐f , (NHC = 1,3‐diethyl‐(5,6‐dimethyl)benzimidazolin‐2‐ylidene 1a , 1,3‐dicyclohexylmethyl‐(5,6‐dimethyl)benzimidazolin‐2‐ylidene 1b and 1,3‐dibenzyl‐(5,6‐dimethyl)benzimidazolin‐2‐ylidene 1c ) were synthesized from the transmetallation reaction of Ag‐NHC with [(η6‐arene)RuCl2]2 and characterized. The ruthenium (II)‐NHC complexes 2a‐f were developed as effective catalysts for α‐alkylation of ketones and synthesis of bioactive quinoline using primary/amino alcohols as coupling partners respectively. The reactions were performed with 0.5 mol% catalyst load in 8 h under aerobic condition and the maximum yield was up to 96%. Besides, the different alkyl wingtips on NHC and arene moieties were studied to differentiate the catalytic robustness of the complexes in the transformations. 相似文献
3.
Jiahao Liu Weikang Li Dr. Yinwu Li Prof. Dr. Yan Liu Prof. Dr. Zhuofeng Ke 《化学:亚洲杂志》2021,16(20):3124-3128
The first implementation of a molybdenum complex with an easily accessible bis-N-heterocyclic carbene ligand to catalyze β-alkylation of secondary alcohols via borrowing-hydrogen (BH) strategy using alcohols as alkylating agents is reported. Remarkably high activity, excellent selectivity, and broad substrate scope compatibility with advantages of catalyst usage low to 0.5 mol%, a catalytic amount of NaOH as the base, and H2O as the by-product are demonstrated in this green and step-economical protocol. Mechanistic studies indicate a plausible outer-sphere mechanism in which the alcohol dehydrogenation is the rate-determining step. 相似文献
4.
In an attempt to convert the carcinogenic benzene which is almost restricted for its use in gasoline, alkylation reaction with olefin 1-hexene has been conducted on various zeolites. Four zeolites having different pore topology and pore size have been applied as solid acid catalysts for effective production of alkylate in a liquid phase, solvent-less low temperature reaction. The textural properties of all the four zeolites (ZSM-5, MOR, BEA, HY) have been characterized for crystal morphology by TEM, crystal structure by XRD and FTIR, BET for surface area, N2 sorption for porosity and TPD for acidity. Among the zeolite, BEA possessed high surface area (600.61 m2/g) and enhanced meso pores volume (0.3956 cm3/g) as compared to other zeolite samples. The performance of BEA was also observed to be superior in the liquid phase alkylation of benzene with 1-hexene in a batch reactor under autogenous pressure without using any solvent. At the optimum reaction conditions, the benzene conversion was 86.6 wt% and 3-Phenylhexane, 2-Phenylhexane yield were about 47.9 wt% and 38.7 wt% respectively on this catalyst. The BEA also exhibited longer time-on-stream and reusability performance, thus offers an attractive route for converting benzene into valuable (3-Phenylhexane, 2-Phenylhexane) alkylate product useful for the manufacturing of fine chemicals, dyestuff, detergents and scents. 相似文献
5.
Jian Chen Lifu Wu Yue Zhao Prof. Shaolin Zhu 《Angewandte Chemie (International ed. in English)》2023,62(44):e202311094
Catalytic methods which control multiple stereogenic centers simultaneously are highly desirable in modern organic synthesis and chemical manufacturing. Herein, we report a regio-, enantio-, and diastereoselective NiH-catalyzed hydroalkylation process which proceeds with simultaneous control of vicinal stereocenters originating from two readily accessible partners, prochiral internal alkenes (enamides or enecarbamates) and racemic alkyl electrophiles (α-bromoamides or Katritzky salts). This reaction produces high-value β-aminoamides and their derivatives under mild conditions and with precise selectivity. Preliminary studies of the mechanism indicate that the reaction involves an enantioselective syn-hydronickelation to generate an enantiomerically enriched alkylnickel(II) species. Subsequent enantioconvergent alkylation with a racemic alkyl electrophile generates the desired product as a single stereoisomer. 相似文献
6.
Naoki Tsuchiya Tetsuhiro Yamamoto Hiroki Akagawa Prof. Dr. Takashi Nishikata 《Angewandte Chemie (International ed. in English)》2023,62(21):e202301343
Herein, we report a copper-catalyzed stereospecific fluorination involving CsF and α-bromocarboxamides as tertiary alkyl sources that, unlike traditional stereospecific routes involving stereoinversive SN2 reactions, proceeds with retention of stereochemistry. The developed stereospecific Cu-catalyzed reaction is among the most efficient methods for synthesizing fluorinated molecules that possess highly congested stereogenic carbon centers. Mechanistic studies revealed that the combined reactivity of CuF2 and Cs salt is essential for completing the catalytic cycle. Our catalytic system underwent fluorination exclusively with tertiary alkyl bromides and did not react with primary alkyl bromides, indicating that this stereospecific fluorination methodology is suitable for synthesizing fluorinated building blocks possessing stereo-defined F-containing tertiary carbon stereogenic center. 相似文献
7.
Si-Yong Yin Qiansujia Zhou Dr. Chen-Xu Liu Prof. Dr. Qing Gu Prof. Dr. Shu-Li You 《Angewandte Chemie (International ed. in English)》2023,62(37):e202305067
Enantioselective synthesis of N−N biaryl atropisomers is an emerging area but remains underexplored. The development of efficient synthesis of N−N biaryl atropisomers is in great demand. Herein, the construction of N−N biaryl atropisomers through iridium-catalyzed asymmetric C−H alkylation is reported for the first time. In the presence of readily available Ir precursor and Xyl-BINAP, a variety of axially chiral molecules based on indole-pyrrole skeleton were obtained in good yields (up to 98 %) with excellent enantioselectivity (up to 99 % ee). In addition, N−N bispyrrole atropisomers could also be synthesized in excellent yields and enantioselectivity. This method features perfect atom economy, wide substrate scope, and multifunctionalized products allowing diverse transformations. 相似文献
8.
Yun-Cheng Luo Ming-Kuan Wang Ling-Chao Yu Prof. Dr. Xingang Zhang 《Angewandte Chemie (International ed. in English)》2023,62(37):e202308690
The selective transition-metal catalyzed C−F bond functionalization of inexpensive industrial fluorochemicals represents one of the most attractive approaches to valuable fluorinated compounds. However, the selective C(sp2)−F bond carbofunctionalization of refrigerant hydrofluoroolefins (HFOs) remains challenging. Here, we report a nickel-catalyzed selective C(sp2)−F bond alkylation of HFO-1234yf with alkylzinc reagents. The resulting 2-trifluoromethylalkenes can serve as a versatile synthon for diversified transformations, including the anti-Markovnikov type hydroalkylation and the synthesis of bioactive molecule analogues. Mechanistic studies reveal that lithium salt is essential to promote the oxidative addition of Ni0(Ln) to the C−F bond; the less electron-rich N-based ligands, such as bipyridine and pyridine-oxazoline, feature comparable or even higher oxidative addition rates than the electron-rich phosphine ligands; the strong σ-donating phosphine ligands, such as PMe3, are detrimental to transmetallation, but the less electron-rich and bulky N-based ligands, such as pyridine-oxazoline, facilitate transmetallation and reductive elimination to form the final product. 相似文献
9.
Peng Zhu Jinshan Wang Fei Xia Wei Zhang Haiou Liu Prof. Xiongfu Zhang 《欧洲无机化学杂志》2023,26(9):e202200664
Sheet-like ZSM-5 has been regarded as a promising material for catalytic applications due to its diffusion superiority. However, it still remains a challenge to obtain a desirable sheet-like morphology because of the complex synthesis process of zeolites. Here, a facile strategy for synthesizing sheet-like ZSM-5 is developed by only adding ethanol as zeolite growth modifier in the synthesis gel. It is thought that ethanol might be preferentially absorbed on the {010} surface of zeolite crystals, interact with the exposed silicon hydroxyl groups on the crystal {010} facet, and suppress the growth of b axis, resulting in the sheet-like shape. Through finely tunning synthesis parameters, sheet-like ZSM-5 crystals with thin b-axis thickness of 90 nm and different aspect ratios could be obtained. Owing to its shorter diffusion path and optimized acidity, sheet-like ZSM-5 exhibits better catalytic performance than conventional ZSM-5 in the alkylation of benzene with ethanol. 相似文献
10.
A new camphor-based 2-phenylimino-2-oxazolidine chiral auxiliary was prepared and it was shown to be a particularly effective chiral auxiliary for asymmetric alkylations affording high yields and diastereoselectivities. The alkylation products were readily cleaved by simple alkaline hydrolysis to give a-alkylated carboxylic acids in good yield and in almost enatiomerically pure form. 相似文献