80463-22-5Relevant academic research and scientific papers
Iron(III) Nitrate/TEMPO-Catalyzed Aerobic Alcohol Oxidation: Distinguishing between Serial versus Integrated Redox Cooperativity
Mao, Kaining,Nutting, Jordan E.,Stahl, Shannon S.
supporting information, p. 10565 - 10570 (2021/07/28)
Aerobic alcohol oxidations catalyzed by transition metal salts and aminoxyls are prominent examples of cooperative catalysis. Cu/aminoxyl catalysts have been studied previously and feature "integrated cooperativity", in which CuII and the aminoxyl participate together to mediate alcohol oxidation. Here we investigate a complementary Fe/aminoxyl catalyst system and provide evidence for "serial cooperativity", involving a redox cascade wherein the alcohol is oxidized by an in situ-generated oxoammonium species, which is directly detected in the catalytic reaction mixture by cyclic step chronoamperometry. The mechanistic difference between the Cu- and Fe-based catalysts arises from the use iron(III) nitrate, which initiates a NOx-based redox cycle for oxidation of aminoxyl/hydroxylamine to oxoammonium. The different mechanisms for the Cu- and Fe-based catalyst systems are manifested in different alcohol oxidation chemoselectivity and functional group compatibility.
KB3H8: An environment-friendly reagent for the selective reduction of aldehydes and ketones to alcohols
Li, Xinying,Mi, Tongge,Guo, Wenjing,Ruan, Zhongrui,Guo, Yu,Ma, Yan-Na,Chen, Xuenian
, p. 12776 - 12779 (2021/12/10)
Selective reduction of aldehydes and ketones to their corresponding alcohols with KB3H8, an air- and moisture-stable, nontoxic, and easy-to-handle reagent, in water and THF has been explored under an air atmosphere for the first time. Control experiments illustrated the good selectivity of KB3H8 over NaBH4 for the reduction of 4-acetylbenzaldehyde and aromatic keto esters. This journal is
Visible Light Induced Reduction and Pinacol Coupling of Aldehydes and Ketones Catalyzed by Core/Shell Quantum Dots
Xi, Zi-Wei,Yang, Lei,Wang, Dan-Yan,Feng, Chuan-Wei,Qin, Yufeng,Shen, Yong-Miao,Pu, Chaodan,Peng, Xiaogang
, p. 2474 - 2488 (2021/02/05)
We present an efficient and versatile visible light-driven methodology to transform aryl aldehydes and ketones chemoselectively either to alcohols or to pinacol products with CdSe/CdS core/shell quantum dots as photocatalysts. Thiophenols were used as proton and hydrogen atom donors and as hole traps for the excited quantum dots (QDs) in these reactions. The two products can be switched from one to the other simply by changing the amount of thiophenol in the reaction system. The core/shell QD catalysts are highly efficient with a turn over number (TON) larger than 4 × 104 and 4 × 105 for the reduction to alcohol and pinacol formation, respectively, and are very stable so that they can be recycled for at least 10 times in the reactions without significant loss of catalytic activity. The additional advantages of this method include good functional group tolerance, mild reaction conditions, the allowance of selectively reducing aldehydes in the presence of ketones, and easiness for large scale reactions. Reaction mechanisms were studied by quenching experiments and a radical capture experiment, and the reasons for the switchover of the reaction pathways upon the change of reaction conditions are provided.
Interrupting the Barton?McCombie reaction: Aqueous deoxygenative trifluoromethylation of o-alkyl thiocarbonates
Liu, Zhi-Yun,Cook, Silas P.
supporting information, p. 808 - 813 (2021/02/01)
The site-selective trifluoromethylation of aliphatic systems remains an important challenge. This work describes a light-driven, copper-mediated trifluoromethylation of O-alkyl thiocarbonates. The reaction provides broad functional group tolerance (e.g., alkyne, alkene, phenol, free alcohol, electron-rich and -deficient arenes), thereby offering orthogonality and practicality for trifluoromethylation. A radical organometallic mechanism is proposed.
Continuous-Flow Amide and Ester Reductions Using Neat Borane Dimethylsulfide Complex
?tv?s, Sándor B.,Kappe, C. Oliver
, p. 1800 - 1807 (2020/02/27)
Reductions of amides and esters are of critical importance in synthetic chemistry, and there are numerous protocols for executing these transformations employing traditional batch conditions. Notably, strategies based on flow chemistry, especially for amide reductions, are much less explored. Herein, a simple process was developed in which neat borane dimethylsulfide complex (BH3?DMS) was used to reduce various esters and amides under continuous-flow conditions. Taking advantage of the solvent-free nature of the commercially available borane reagent, high substrate concentrations were realized, allowing outstanding productivity and a significant reduction in E-factors. In addition, with carefully optimized short residence times, the corresponding alcohols and amines were obtained in high selectivity and high yields. The synthetic utility of the inexpensive and easily implemented flow protocol was further corroborated by multigram-scale syntheses of pharmaceutically relevant products. Owing to its beneficial features, including low solvent and reducing agent consumption, high selectivity, simplicity, and inherent scalability, the present process demonstrates fewer environmental concerns than most typical batch reductions using metal hydrides as reducing agents.
Base-Free Iron Catalyzed Transfer Hydrogenation of Esters Using EtOH as Hydrogen Source
Farrar-Tobar, Ronald A.,Wozniak, Bartosz,Savini, Arianna,Hinze, Sandra,Tin, Sergey,de Vries, Johannes G.
supporting information, p. 1129 - 1133 (2019/01/04)
Herein, we report on the use of the iron pincer complex Iron-MACHO-BH, in the base-free transfer hydrogenation of esters with EtOH as a hydrogen source. More than 20 substrates including aromatic and aliphatic esters and lactones were reduced affording the desired primary alcohols and diols with moderate to excellent isolated yields. It is also possible to reduce polyesters to the diols with this method, enabling a novel way of plastic recycling. Reduction of the renewable substrate methyl levulinate proceeds to form 1,4-pentanediol directly. The yields are largely governed by the equilibrium between the alcohol and the ethyl ester.
Ambient-pressure hydrogenation of ketones and aldehydes by a metal-ligand bifunctional catalyst [Cp*Ir(2,2′-bpyO)(H2O)] without using base
Wang, Rongzhou,Qi, Jipeng,Yue, Yuancheng,Lian, Zhe,Xiao, Haibin,Zhuo, Shuping,Xing, Lingbao
, (2019/07/30)
An efficient catalytic system for hydrogenation of ketones and aldehydes using a Cp*Ir complex [Cp*Ir(2,2′-bpyO)(H2O)] bearing a bipyridine-based functional ligand as catalyst has been developed. A wide variety of secondary and primary alcohols were synthesized by the catalyzed hydrogenation of ketones and aldehydes under facile atmospheric-pressure without a base. The catalyst also displays an excellent chemoselectivity towards other carbonyl functionalities and unsaturated motifs. This catalytic system exhibits high activity for hydrogenation of ketones and aldehydes with H2 gas.
Chemoselective reduction of aldehydes: Via a combination of NaBH4 and acetylacetone
Sui, Guoqing,Lv, Qingyun,Song, Xiaoqing,Guo, Huihui,Dai, Jiatong,Ren, Li,Lee, Chi-Sing,Zhou, Wenming,Hao, Hong-Dong
supporting information, p. 15793 - 15796 (2019/10/19)
A bench-stable combination of NaBH4-acetylacetone was developed for the efficient chemoselective reduction of aldehydes in the presence of ketones. This method offers a useful synthetic protocol for distinguishing carbonyl reaction sites, and its synthetic utility is reflected by its moisture tolerance and high efficiency in a variety of complex settings.
Syntheses, characterisation, and catalytic role of (η5-C5Me5)Rh(III) guanidinato complexes in transfer hydrogenation (TH) and TH-etherification
Kumar, Robin,Thirupathi, Natesan
, p. 33890 - 33904 (2017/07/17)
A family of air stable half sandwich meal guanidinato complexes ([(η5-Cp?)MCl{κ2(N,N′)((ArN)2C-N(H)Ar)}]) (M = Rh and Ir; Cp? = C5Me5; Ar = aryl) were synthesized in good yield and characterised by elemental analyses, IR, and NMR (1H, 13C, and 19F) spectroscopy. The geometry of the metal and the conformations of the guanidinate ligands in the complexes were studied by single crystal X-ray diffraction. The solution behaviour of representative complexes was investigated by detailed NMR studies including variable temperature and variable concentration 1H NMR measurements. The new complexes were screened as catalysts for transfer hydrogenation (TH) of acetophenone under basic and base free conditions and from these experiments, ([(η5-Cp?)RhCl{κ2(N,N′)((ArN)2C-N(H)Ar)}]) (Ar = 3,5-(CF3)2C6H3; 3) was chosen as the preferred catalyst due to its slightly better catalytic activity than other complexes. The utility of 3 in TH of a variety of carbonyl compounds was explored under basic and base free conditions. Tandem catalysis involving TH of a carbonyl group and etherification of the resulting -CH2OH group in reduction products of salicylaldehyde, 2-hydroxy-1-naphthaldehyde and 5-(hydroxymethyl)furfural was achieved in the presence of 3 under base free conditions. The role of the guanidinate ligands in the complexes for basic and base free TH of carbonyl compounds and TH-etherification tandem catalysis is discussed. Plausible mechanisms for TH and TH-etherification are outlined.
Zinc-Mediated Efficient and Selective Reduction of Carbonyl Compounds
Mandal, Tirtha,Jana, Snehasish,Dash, Jyotirmayee
, p. 4972 - 4983 (2017/09/13)
We herein describe for the first time that an optimized combination of Zn and NH4Cl can be used for the selective reduction of aldehydes and ketones to the corresponding alcohols. The aldehyde and keto groups are selectively reduced in the presence of azide, cyano, epoxy, ester, and carbon–carbon double-bond functional groups. A broad functional-group compatibility, chemoselective reduction of aldehydes in the presence of ketones, and selective reduction of isatins at the C3 carbonyl group are the highlights of the present method.
