Efficient deuterium labelling of alcohols in deuterated water catalyzed by ruthenium pincer complexes

A series of isolated or preformed in-situ aliphatic PNP-type pincer ruthenium complexes have been evaluated for deuterium labelling of alcohols' C-H functions with deuterium oxide. Under our catalytic conditions, pincer-supported ruthenium complexes bearing cyclohexyl substituents on the phosphorous atoms have been found to be the most efficient and regioselective catalysts for α-deuteration of primary alcohols, affording up to 94% of α-C-H deuteration with only 5% of β-C-H deuteration in the case of n-butanol.     

Asymmetric intramolecular Diels-Alder reactions of trienals catalyzed by chiral ruthenium Lewis acids

Chiral single-point binding ruthenium Lewis acid catalysts [Ru(acetone)((S,S)-BIPHOP-F)(Cp)][SbF6] ((S,S)-1a) and [Ru(acetone)((S,S)-BIPHOP-F)(indenyl)][SbF6] ((S,S)-1b) efficiently catalyze intramolecular Diels-Alder (IMDA) reactions of trienals under mild conditions to afford the endo cycloaddition products as the major products in good yields with high diastereo- and enantioselectivities.     

Enantioselective Diels-Alder reactions of unsaturated beta-ketoesters catalyzed by chiral ruthenium PNNP complexes

We report here dicationic ruthenium PNNP complexes that promote the enantioselective Diels-Alder reaction of alpha-methylene beta-ketoesters with various dienes. Complex [Ru(OEt2)2(PNNP)](PF6)2, formed in situ from [RuCl2,(PNNP)] and (Et3O)PF6 (2 equiv.), catalyzes the Diels-Alder reaction of such unsaturated beta-ketoesters to give novel alkoxycarbonyltetrahydro-1-indanone derivatives (nine examples) with up to 93% ee. The crystal structure of the substrate-catalyst adduct shows that the lower face of the substrate is shielded by a phenyl ring of the PNNP ligand, which accounts for the high enantioselectivity. The attack of the diene from the open re enantioface of the unsaturated beta-ketoester is consistent with the absolute configuration of the product. A useful application of this method is the reaction with Dane's diene to give estrone derivatives with up to 99% ee and an ester-exo:endo ratio of up to 145:1 (after recrystallization). Besides the enantioselective formation of all-carbon quaternary centers, this methodology is notable because unsaturated beta-ketoesters have been rarely used in Diels-Alder reactions. Furthermore, enantiomerically pure estrone derivatives are interesting in view of their potential applications, including the treatment of breast cancer.     

Aerobic oxidation of amines to imines catalyzed by a ruthenium complex under solvent-free conditions

A ruthenium complex [Et₃NH]₂[Ru(dipic)Cl₃] showed high efficiency in the homo-coupling of primary amines and cross-coupling of benzylamine with anilines and aliphatic amines to the corresponding imines under air and solvent-free conditions. This protocol is an atom-economical green process and tolerates various substrates bearing both electron-donating and electron-withdrawing substituents.     

Palladium catalyzed coupling reactions of diiodoarenes with allylic and homoallylic alcohols

A sequential transformation consisting of a twofold Heck reaction of 1,2-diiodobenzene ( 14 ) with allyl alcohol ( 2 ) followed by an intramolecular aldol condensation is suitable for the construction of the benzocyclohept-2-ene-2-carboxaldehyde ( 15 ). Under the same reaction conditions 1,8-diiodonaphthalene ( 7 ) leads to 1-acenaphthenyl-methanol ( 6 ), 2-(1-acenaphthenyl)-ethanol ( 8 ), 1-(1-acenaphthenyl)-ethanol ( 11 ), 5-(1,8-naphthalena)-nonan-2,8-dione ( 12 ) and 5-(1-naphthyl)-3-methylpentan-2-on ( 13 ) mainly     

磺酸功能化离子液体催化甘油与甲醇醚化反应

考察了[HSO₃-bmim]CF₃SO₃、[HSO₃-bmim]P-TSA、[HSO₃-bmim]HSO₄和[HSO₃-bmim]H₂PO₄四种磺酸功能化离子液体对甘油与甲醇醚化反应的影响。结果表明,离子液体的催化性能与其酸强度相关联,[HSO₃-bmim]CF₃SO₃离子液体的酸强度最强,其催化性能也最好。以[HSO₃-bmim]CF₃SO₃为催化剂,在w([HSO₃-bmim]CF₃SO₃)/w(甘油)=0.5:1(质量比)、n(甲醇)/n(甘油)=8:1(摩尔比)、反应温度190℃、反应时间8 h时,甘油的转化率为84.5%,单甲基甘油醚的选择性为41.4%,二甲基甘油醚和三甲基甘油醚的联合选择性为34.1%。在此基础上,提出了离子液体[HSO₃-bmim]CF₃SO₃催化甘油与甲醇醚化反应的反应机理。     

TEMPO催化醇氧化反应进展

选择性催化氧化醇类化合物为相应的醛或酮是一类重要的官能团转化反应.四甲基哌啶氧化物(TEMPO)是一种含有稳定的氮氧自由基(NO·)的有机小分子催化剂,NO·可通过自身的强选择性,在加快醛或酮转化的同时不会过氧化成为羧酸.本文阐述了TEMPO催化体系催化醇选择性氧化反应的机理,在此基础上详述了过渡金属/TEMPO、非过...     

多金属氧酸盐催化的醇类分子氧氧化研究进展

多金属氧酸盐作为一类廉价易得的绿色催化剂,在研究开发醇类分子氧氧化新型催化剂体系过程中起着重要的作用。概述了近十几年来多金属氧酸盐对醇类分子氧氧化的催化作用,催化剂体系主要有磷钒钼基类、磷钨酸类等,并介绍了多金属氧酸盐结合超临界二氧化碳体系的研究现状。指出利用多金属氧酸盐结合超临界二氧化碳有可能开发出完全清洁的醇类氧化技术。     

Hydrazine oxidation catalyzed by ruthenium hexacyanoferrate-modified glassy carbon electrode

A ruthenium (III) hexacyanoferrate (Ru(HCF)) film coated on a glassy carbon electrode was explored as an electrocatalyst for hydrazine oxidation. Surface cyclic voltammograms of Ru(HCF) film showed four reversible one-electron redox waves. Two, which corresponded to the redox processes of Ru(III)/Ru(IV) and Fe(II)/Fe(III), were identified to be responsible for the catalytic activity of hydrazine oxidation. Kinetic studies using potential scan rate dependency, Tafel plots, and rotating disk electrode technique found that this catalyzed hydrazine oxidation was a complete four-electron/four-proton process producing N₂, with the rate determining step possibly a one-electron process with a transfer coefficient (α) of ~0.31–0.36. In addition, based on kinetic analysis and findings in the literature, we propose a possible reaction mechanism for catalyzed hydrazine oxidation in order to facilitate further understanding.     

Extractive reactions with cationic exchange resins as catalysts (acetalization of aldehydes with alcohols)

The acid catalysed acetalization of aldehydes such as formaldehyde, acetaldehyde, glyoxal and glyoxylic acid, with alcohols are reversible reactions. In order to enhance the conversion of aldehydes, extractive reactions were carried out with the alcohols (e.g. 2-ethyl hexanol and n-butanol) having very low to low solubility in water. In such cases alcohols, in addition to being reactants act as extractive solvents for the acetals formed in the reaction. An experimental investigation was carried out using cation-exchange resins (Indion-130, Amberlist-15 and Amberlite IR-120) as catalysts and significant conversion levels were realised for the reactions of formaldehyde and acetaldehyde; results were not encouraging for the extractive reactions of glyoxal and glyoxylic acid. The effect of different parameters, such as catalyst loading, temperature, mole ratio and aqueous phase concentration of aldehyde on the rate of reaction was studied.     

Competitive reactions catalyzed by NiMo-containing zeolites

The rates of benzene hydrogenation and of n-heptane hydroconversion were measured simultaneously over a series of bifunctional catalysts. The catalysts were Y zeolites containing a Ni or Mo sulfide. At 280 °C, and for the more acidic catalysts, both rates appeared linearly correlated, suggesting that the hydrogenation function was limiting.     

Household LED irradiation under air: cationic polymerization using iridium or ruthenium complex photocatalysts

Household LED bulbs are used to promote the ring-opening photopolymerization of epoxides in the presence of a photocatalyst (here tris(2-phenylpyridine)iridium [Ir(ppy)₃] or tris(1,10-phenanthroline)ruthenium(II) [Ru(phen)₃²⁺] complex) and a silyl radical source. Remarkably, even under this very soft irradiation (light intensity lower than 10 mW/cm2), excellent polymerization profiles are obtained i.e., this is the first reported use of such very convenient irradiation devices for photopolymerization processes. The role of the silane and other hydrogen donors is outlined.     

单事件方法在酸催化复杂反应动力学领域的研究进展

对单事件方法的研究发展概况进行了介绍,同时对单事件方法在加氢裂化、加氢异构化、催化裂化、烷基化和甲醇制烯烃反应动力学模拟中的应用进展进行了综述。单事件方法的应用研究表明其在酸催化复杂反应动力学研究中将有重要意义和广泛的应用前景。     

钨锗酸的催化脱水反应

报道了钨锗酸对醇脱水成醚或成烯的催化反应。     

阳离子交换树脂催化合成阿魏酸甲酯的研究

以甲醇和阿魏酸为原料,强酸性阳离子交换树脂为催化剂,直接酯化合成了阿魏酸甲酯.考察了树脂类型、催化剂用量、反应时间、反应温度、醇酸物质的量比、催化剂重复使用性等因素对反应的影响.确定了较佳反应条件为:m(732树脂):m(阿魏酸)=12:100,n(甲醇):n(阿魏酸)=7:1,加热回流(65℃)反应7 h,在此反应条件下阿魏酸的转化率为82.6%.催化剂能够重复使用3次而保持转化率无显著下降.产品用质谱和红外光谱进行表征.经过测试,产品对于氨酸酪酶活性的抑制作用良好.     

4-烯丙氧基-2,6-二(N,N-二乙胺基甲基)吡啶钌配合物催化苯乙酮氢转移反应

以配体4-烯丙氧基-2,6-二(N,N-二乙胺基甲基)吡啶与三苯基膦氯化钌配位化合物生成新的钌催化剂,催化苯乙酮氢转移反应。考察温度、碱强度、底物浓度及产物等对反应的影响。研究结果表明:在N2气氛下,82℃,苯乙酮、钌配合物和KOH的初始摩尔比为250∶1∶12,反应6 h,苯乙酮的转化率达到99.8%,该催化剂具有很好的催化活性和稳定性。     

Efficient and selective oxidation of alcohols catalyzed by oxo-rhenium complexes

This work reports the catalytic activity of several oxo-rhenium complexes in the oxidation of alcohols, using a sulfoxide as oxidant agent. The catalytic system bis(4-chlorophenyl) sulfoxide/ReOCl₃(PPh₃)₂ (10 mol%) proved to be efficient for the oxidation of primary and secondary alcohols to the corresponding aldehydes and ketones. The primary alcohols are selectively oxidized to the corresponding aldehydes with no further oxidation to acids. The bis(4-chlorophenyl) sulfide, isolated as by-product in high yields, can be used as a substrate in other reactions or can be oxidized and reused in this procedure.