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951.
Metal-catalyzed enantioselective allylation, which involves the substitution of allylic metal intermediates with a diverse range of different nucleophiles or S(N)2'-type allylic substitution, leads to the formation of C-H, -C, -O, -N, -S, and other bonds with very high levels of asymmetric induction. The reaction may tolerate a broad range of functional groups and has been applied successfully to the synthesis of many natural products and new chiral compounds. 相似文献
952.
953.
胺是有机分子中最常见且重要的结构之一,广泛存在于天然产物分子、药物、染料、塑料等的分子结构中,开发合成胺的有效方法在化学工业中具有很高的需求但仍充满挑战。在诸多已知有机胺的合成方法中,以氰基为前体还原衍生化制备胺被认为是一条原子经济且绿色可行的方案。然而,氰基中存在稳定的碳氮三重键,还原过程涉及较多中间体,而部分中间体活性比氰基更高,因此反应受还原剂、催化剂、反应条件的影响很大,由氰基选择性制备目标胺结构仍充满挑战。本文从氰基的基本电子结构与反应活性出发,综述了近年来以氰基为原料的官能团胺基化反应,对部分重要反应的催化剂和反应机理做了简要讨论,为设计氰基制胺催化剂和应用工艺提供了新的视角。 相似文献
954.
《Mendeleev Communications》2023,33(4):494-496
A new method for selective C(5)–H alkylation of 2-substituted furans with tertiary and secondary alkyl bromides under photoinduced by visible light (∼460 nm) palladium catalysis has been developed. The method is relied on the use of available Pd(PPh3)4 catalyst under mild conditions (30 ± 5 °C, K2CO3 as base), tolerates to various functional groups in furanic substrates and provides from good to excellent yields of alkylated products. 相似文献
955.
Ramanjulu Abinaya Selvaraj Elavarasan B. Binish Dr. K. Mani Rahulan Prof. Dr. Kalpattu K. Balasubramanian Dr. Kamaraj Manokaran Dr. Elumalai Varathan Dr. Baburaj Baskar 《European journal of organic chemistry》2023,26(4):e202201098
Herein we report a simple and efficient oxidative coupling of various aryl methyl amines with diverse coupling partners, such as o-phenylenediamine (benzene-1,2-diamine), 2-aminobenzenethiol and 2-aminobenzamide, to synthesize the corresponding heterocycles using scalable and reusable heterogeneous catalysts under visible light irradiation. A systematic investigation led to the synthesis of benzimidazoles, benzothiazoles and quinazolinones under air atmosphere in very good to excellent yields. The strategy is atom economical and found to be tolerance towards different functional groups, and wide range of substrate scope. Furthermore, the methodology was demonstrated for its suitability on scale up and reusability. The density functional theory (DFT) calculations and the analysis of band structures of pristine and Ba doped CoMoO4 systems showed that the doping of Ba in place of Co improved the catalytic performance of the system. 相似文献
956.
Prof. Domenico C. M. Albanese Dr. Michele Penso 《European journal of organic chemistry》2023,26(19):e202300224
Phase Transfer Catalysis (PTC) is a powerful tool to perform reactions in a practical fashion, both in laboratory and industrial scale. Significant cost savings and major process improvements can be achieved in reactions performed under PTC conditions. In the last few years remarkable results in stereoselective reactions were achieved using chiral, non-racemic quaternary ammonium salts. Moreover, the use of bulky, chiral phosphate anions paired with achiral cations to generate lipophilic ion pairs allowed to design new avenues for the stereoselective construction of important building blocks. Hydrogen bond interactions were also shown to provide new pathways for asymmetric nucleophilic substitutions using insoluble reagents under PTC conditions. This Review will focus on recent advances in developing practical synthetic routes to construct molecules in a stereoselective fashion under PTC conditions. 相似文献
957.
Heteroleptic and homoleptic iron(III) complexes supported by a tris(N-heterocyclic carbene) borate ligand have been prepared and crystallographically characterized. The strong electron-donating character of the tris(carbene) donor was revealed by UV-vis absorption spectroscopy and electrochemical measurements combined with quantum chemical calculations. The catalytic activity of each complex was evaluated in cyclohexane oxidation reaction using meta-chloroperoxybenzoic acid (=mCPBA) as an oxidant, and both complexes show high catalytic activity and selectivity with TON=∼350 and A/(K+L)=8–10. Mechanistic studies suggested that radical-chain processes are involved in the reaction due to mCPBA acting as a one-electron oxidant, concomitant with the pathway of metal-based reactive species. Moreover, it was found that the homoleptic and heteroleptic complexes differed significantly in the involvement of metal-based active species, with the homoleptic complex exhibiting more metal-based reactions. 相似文献
958.
959.
960.
Formaldehyde decomposition is not only an attractive method for hydrogen production, but also a potential approach for gaseous formaldehyde removal. In this research, we prepare some assembled organoruthenium through coordination reaction between Ru(p-Cymene)Cl2 and bridge-linking ligands. It is a creative approach for Ru(p-Cymene)Cl2 conversion into heterogeneous particles. The rigidity of bridge-linking ligand enables assembled organoruthenium to have highly ordered crystalline structure, even show clear crystal lattice with spacing of 0.19 nm. XPS shows the N−Ru bond are formed between bridge-linking ligand and Ru(p-Cymene)Cl2. The assembled organoruthenium has high abundant active sites for formaldehyde decomposition at low temperature. The reaction rate could increase linearly with temperature and formaldehyde concentration, with a TOF of 2420 h−1 at 90 °C. It is promising for gaseous formaldehyde decomposition in wet air or nitrogen. Formaldehyde conversion is up to 95 % over Ru-DAPM is 4,4′-diaminodiphenylmethane at 90 °C in air. Gaseous formaldehyde decomposition is a two-steps process under oxygen-free condition. Firstly, formaldehyde dissolve in water, and be converted into hydrogen and formic acid through formaldehyde-water shift reaction. Then intermediate formic acid will further decompose into hydrogen and carbon dioxide. We also find formaldehyde decomposition is a synergetic catalysis process of oxygen and water in moist air. Oxygen is conducive to formic acid desorption and decomposition on the active sites, so assembled organoruthenium exhibit slightly higher conversion for formaldehyde decomposition in moist air. This work proposes a distinctive method for gaseous formaldehyde decomposition in the air, which is entirely different from formaldehyde photocatalysis or thermocatalysis oxidation. 相似文献