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Dual utility of a single diphosphine-ruthenium complex: A precursor for new complexes and, a pre-catalyst for transfer-hydrogenation and Oppenauer oxidation
The diphosphine-ruthenium complex, [Ru(dppbz)(CO)2Cl2] (dppbz = 1,2-bis(diphenylphosphino)benzene), where the two carbonyls are mutually cis and the two chlorides are trans, has been found to serve as an efficient precursor for the synthesis of new complexes. In [Ru(dppbz)(CO)2Cl2] one of the two carbonyls undergoes facile displacement by neutral monodentate ligands (L) to afford complexes of the type [Ru(dppbz)(CO)(L)Cl2] (L = acetonitrile, 4-picoline and dimethyl sulfoxide). Both the carbonyls in [Ru(dppbz)(CO)2Cl2] are displaced on reaction with another equivalent of dppbz to afford [Ru(dppbz)2Cl2]. The two carbonyls and the two chlorides in [Ru(dppbz)(CO)2Cl2] could be displaced together by chelating mono-anionic bidentate ligands, viz. anions derived from 8-hydroxyquinoline (Hq) and 2-picolinic acid (Hpic) via loss of a proton, to afford the mixed-tris complexes [Ru(dppbz)(q)2] and [Ru(dppbz)(pic)2], respectively. The molecular structures of four selected complexes, viz. [Ru(dppbz)(CO)(dmso)Cl2], [Ru(dppbz)2Cl2], [Ru(dppbz)(q)2] and [Ru(dppbz)(pic)2], have been determined by X-ray crystallography. In dichloromethane solution, all the complexes show intense absorptions in the visible and ultraviolet regions. Cyclic voltammetry on the complexes shows redox responses within 0.71 to -1.24 V vs. SCE. [Ru(dppbz)(CO)2Cl2] has been found to serve as an excellent pre-catalyst for catalytic transfer-hydrogenation and Oppenauer oxidation.
Mukherjee, Aparajita,Bhattacharya, Samaresh
p. 15617 - 15631
(2021/05/19)

Green Oxidation of Ketones to Lactones with Oxone in Water
Cyclic ketones were quickly and quantitatively converted to 5-, 6-, and 7-membered lactones, very important synthons, by treatment with Oxone, a cheap, stable, and nonpollutant oxidizing reagent, in 1 M NaH2PO4/Na2HPO4 water solution (pH 7). Under such simple and green conditions, no hydroxyacid was formed, thus making the adoption of more complex and non-eco-friendly procedures previously developed to avoid lactone hydrolysis unnecessary. With some changes, the method was successfully applied also to water-insoluble ketones such as adamantanone, acetophenone, 2-indanone, and the challenging cycloheptanone.
Bertolini, Valentina,Appiani, Rebecca,Pallavicini, Marco,Bolchi, Cristiano
p. 15712 - 15716
(2021/11/01)

Method for catalytically synthesizing δ - cyclopentanone by amino acid ionic liquid
The invention relates to a method for catalyzing oxo-synthesis of sigma-cyclovalerolactone from cyclopentanone by amino-acid ionic liquid. The method is characterized by comprising the steps of catalyzing hydrogen peroxide to oxidate the cyclopentanone by a catalyst, i.e., ionic liquid synthesized from proline, aspartic acid, trifluoromethane-sulfonic acid and phosphotungstic heteropoly acid, thereby producing the sigma-cyclovalerolactone, wherein the mole ratio of the proline and the aspartic acid to the trifluoromethane-sulfonic acid and the phosphotungstic heteropoly acid is 1: 1. The amino-acid ionic liquid has the advantages of low price and availability of the raw materials, simple preparation method high biodegradability and environmental friendliness; the amino-acid ionic liquid contains a -COOH functional group, can be used for providing an appropriate acidic environment for the preparation of the sigma-cyclovalerolactone through oxidating the cyclopentanone, and is high in catalysis activity; in addition, the amino-acid ionic liquid is soluble in water, is easy to separate and recover and cycle use efficiency is high.
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Paragraph 0019-0036

(2021/05/19)

Lipase catalysed oxidations in a sugar-derived natural deep eutectic solvent
Chemoenzymatic oxidations involving the CAL-B/H2O2 system was developed in a sugar derived Natural Deep Eutectic Solvent (NaDES) composed by a mixture of glucose, fructose and sucrose. Good to excellent conversions of substrates like cyclooctene, limonene, oleic acid and stilbene to their corresponding epoxides, cyclohexanone to its corresponding lactone and 2-phenylacetophenone to its corresponding ester, demonstrate the viability of the sugar NaDES as a reaction medium for epoxidation and Baeyer-Villiger oxidation.
Vagnoni, Martina,Samorì, Chiara,Pirini, Daniele,Vasquez De Paz, Maria Katrina,Gidey, Dawit Gebremichael,Galletti, Paola
(2021/05/06)

Highly Dispersed Sn-beta Zeolites as Active Catalysts for Baeyer-Villiger Oxidation: The Role of Mobile, in Situ Sn(II)O Species in Solid-State Stannation
Solid-state incorporation of Sn into beta (β) zeolites is a fast and efficient method to obtain Lewis acidic Snβ catalysts with high activity. The present work emphasizes the fundamental role of the heat-treatment atmosphere in the solid-state incorporation of active Sn in zeolites. Via an array of characterization tools including N2-physisorption, X-ray diffraction, diffuse reflectance UV-vis spectrocopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and 119Sn M?ssbauer spectroscopy, it is shown that preheating under an inert atmosphere (pre-pyrolysis) prior to air-calcination affords Sn-β catalysts with the highest Sn dispersion and significantly less extra-framework SnO2 compared to the classic calcination. In situ characterization during pre-pyrolysis by temperature-programed decomposition-mass spectrometry, thermogravimetric analysis, and 119Sn M?ssbauer spectroscopy reveals the in situ generation of Sn(II)O species that are more mobile than Sn(IV)O2 species generated during calcination. This mobility property essentially enables the high Sn dispersion in Snβ. Based on this knowledge, active sites per catalyst weight are maximized while retaining high turn-over frequencies for the Baeyer-Villiger oxidation reaction (300 h-1 at 80 °C). For Lewis acid densities above 200 μmol·g-1, the catalytic activity unexpectedly leveled off to 93 mM·h-1, even under kinetic control. We tentatively ascribe the activity plateau to the incorporation of Sn in less favorable T-sites at high Sn-loadings.
Peeters, Elise,Pomalaza, Guillaume,Khalil, Ibrahim,Detaille, Arnaud,Debecker, Damien P.,Douvalis, Alexios P.,Dusselier, Michiel,Sels, Bert F.
p. 5984 - 5998
(2021/05/31)

A Polyoxometalate-Based Inorganic Porous Material with both Proton and Electron Conductivity by Light Actuation: Photocatalysis for Baeyer-Villiger Oxidation and Cr(VI) Reduction
Two-dimensional (2D) crystalline porous materials with designable structures and high surface areas are currently a hot research topic in the field of proton- and electron-conducting materials, which provide great opportunities to orderly accommodate carriers in available spaces and to accurately understand the conducting path. The 2D dual-conductive inorganic framework [Co(H2O)6]2{[Co(H2O)4]4[WZn3(H2O)2(ZnW9O34)2]}·8H2O (Co6Zn5W19) is synthesized by combining [WZn3(H2O)2(ZnW9O34)2]12- (Zn5W19) and a Co(II) ion via a hydrothermal method. Due to the presence of a consecutive H-bonding network, electrostatic interactions, and packing effects between the framework and guest molecules, Co6Zn5W19 displays a high proton conductivity (3.55 × 10-4 S cm-1 under 98% RH and 358 K) by a synergistic effect of the combined components. Additionally, a photoactuated electron injection into the semiconducting materials is an important strategy for switching electronic conductivity, because it can efficiently reduce the frameworks without destroying the crystallinity. I-V curves of a tablet of Co6Zn5W19 in the reduced and oxidized states yield conductivities of 1.26 × 10-6 and 5 × 10-8 S cm-1, respectively. Moreover, Co6Zn5W19 is also successfully applied in the photocatalytic reduction of the toxic Cr(VI) metal ion by utilizing its excellent electronic storage capacity and Baeyer-Villiger (BV) oxidation in a molecular oxygen/aldehyde system.
Du, Wei,Han, Qiuxia,Jiao, Jiachen,Li, Mingxue,Ma, Pengtao,Niu, Jingyang,Si, Chen,Wu, Jingpin
p. 682 - 691
(2021/01/13)

Acceptorless Dehydrogenative Cross-Coupling of Primary Alcohols Catalyzed by an N-Heterocyclic Carbene-Nitrogen-Phosphine Chelated Ruthenium(II) Complex
The acceptorless dehydrogenative cross-coupling of primary alcohols to form cross-esters with the liberation of H2 gas was enabled using a [RuCl(η6-C6H6)(κ2-CNP)][PF6]Cl complex as the catalyst. This sustainable protocol is applicable to a broad range of primary alcohols, particularly for the sterically demanding ones, featuring good functional group tolerance and high selectivity. The good catalytic performance can be attributed to the nitrogen-phosphine-functionalized N-heterocyclic carbene (CNP) ligand, which adopts a facial coordination mode as well as the facile dissociation of coordinated benzene.
Chen, Hua,Cui, Tianhua,Fu, Haiyan,He, Xiaochun,Jiang, Weidong,Li, Ruixiang,Nie, Xufeng,Xu, Jiaqi,Yuan, Maolin,Zhao, Ling,Zheng, Xueli
(2022/04/07)

Selective Aerobic Oxidation of Secondary C (sp3)-H Bonds with NHPI/CAN Catalytic System
Abstract: The direct aerobic oxidation of secondarty C(sp3)-H bonds was achieved in the presence of N-hydroxyphthalimide (NHPI) and cerium ammonium nitrate (CAN) under mild conditions. Various benzylic methylenes could be oxidized to carbonyl compounds in satisfied selectivity while saturated cyclic alkanes could be further oxidized to the corresponding lactones with the catalytic system. Remarkably, 25% of isochroman was converted to corresponding ketone with a selectivity of 96%. The reaction was initiated by hydrogen atom abstraction from NHPI by cerium and nitrates under oxygen atmosphere to form PINO radicals. 2,2,6,6-Tetramethylpiperidine-1-oxyl (TEMPO) addition experiments showed that the oxidation proceeded via a complex radical chain mechanism and an ion pathway. Graphic Abstract: [Figure not available: see fulltext.]
Wang, Lingyao,Zhang, Yuanbin,Yuan, Haoran,Du, Renfeng,Yao, Jia,Li, Haoran
p. 1663 - 1669
(2020/10/21)

(Cyclopentadienone)iron-Catalyzed Transfer Dehydrogenation of Symmetrical and Unsymmetrical Diols to Lactones
Air-stable iron carbonyl compounds bearing cyclopentadienone ligands with varying substitution were explored as catalysts in dehydrogenative diol lactonization reactions using acetone as both the solvent and hydrogen acceptor. Two catalysts with trimethylsilyl groups in the 2- A nd 5-positions, [2,5-(SiMe3)2-3,4-(CH2)4(δ4-C4C= O)]Fe(CO)3 (1) and [2,5-(SiMe3)2-3,4-(CH2)3(δ4-C4C= O)]Fe(CO)3 (2), were found to be the most active, with 2 being the most selective in the lactonization of diols containing both primary and secondary alcohols. Lactones containing five-, six-, and seven-membered rings were successfully synthesized, and no over-oxidations to carboxylic acids were detected. The lactonization of unsymmetrical diols containing two primary alcohols occurred with catalyst 1, but selectivity was low based on alcohol electronics and modest based on alcohol sterics. Evidence for a transfer dehydrogenation mechanism was found, and insight into the origin of selectivity in the lactonization of 1°/2° diols was obtained. Additionally, spectroscopic evidence for a trimethylamine-ligated iron species formed in solution during the reaction was discovered.
Tang, Yidan,Meador, Rowan I. L.,Malinchak, Casina T.,Harrison, Emily E.,McCaskey, Kimberly A.,Hempel, Melanie C.,Funk, Timothy W.
p. 1823 - 1834
(2020/02/04)

Selective aerobic oxidation of cyclic ethers to lactones over Au/CeO2 without any additives
Selective oxidation of ethers to lactones with O2 as a benign oxidant using Au/CeO2 as the catalyst has been developed. The oxygen vacancies and Au0 species on the surface of CeO2 contribute to the activation of O2. The excellent selectivity of lactones is due to the adsorption of ethers and activation of the C(sp3)-H bond on Au/CeO2.
Liu, Shulin,Li, Shaopeng,Shen, Xiaojun,Wang, Yanyan,Du, Juan,Chen, Bingfeng,Han, Buxing,Liu, Huizhen
supporting information
p. 2638 - 2641
(2020/03/10)

Genome mining reveals new bacterial type I Baeyer-Villiger monooxygenases with (bio)synthetic potential
Baeyer-Villiger monooxygenases (BVMOs) are oxidorreductases that catalyze the oxidation of ketones in a very selective manner. By genome mining we detected seven putative type I BVMOs in Bradyrhizobium diazoefficiens USDA 110. As we established the phylogenetic relationships among them and with other type I BVMOs, we found out that they belong to different clades of the phylogenetic tree. Thus, we decided to clone and heterologously express five of them. Three of them, each one from a divergent phylogenetic group, were obtained as soluble proteins, allowing us to proceed with their biocatalytic assessment and enzymatic characterization. As to substrate scope and selectivity, we observed a complementary behavior among the three BVMOs. BVMO2 was the more versatile biocatalyst in whole-cell systems while BVMO4 and BVMO5 showed a narrow substrate profile with preference for linear ketones and particular regioselectivity for (±)-cis-bicyclo[3.2.0]hept-2-en-6-one.
Bianchi, Dario A.,Carabajal, María Ayelén,Ceccoli, Romina D.,Rial, Daniela V.
(2020/03/19)

Effect of pretreatment conditions on acidity and dehydration activity of CeO2-MeOx catalysts
A series of MeOx-modified CeO2 (CeO2-MnOx, CeO2-ZnO, CeO2-MgO, CeO2-CaO, and CeO2-Na2O) catalysts were prepared by the impregnation of CeO2 with corresponding metal nitrates. Acidity and oxidation state of cerium were investigated on both oxidized and reduced catalysts by employing Fourier Transform Infrared spectroscopy (FTIR) on adsorbed pyridine and in situ H2-Temperature Programmed Reduction/X-ray Absorption Spectroscopy (H2-TPR/XAS) techniques, respectively. Metal oxide addition tended to alter both type and number of acid sites on ceria. EXAFS data showed a significant difference in NCe-O between unmodified and CeO2-MeOx, suggesting that added MeOx interferes with vacancy formation on ceria during reduction. In comparison with air-pretreated samples, H2-pretreated ones under similar conversion of 1,5 pentanediol exhibited a higher selectivity towards linear alcohols. Alcohol conversion found to correlate with total acidity (i.e., Br?nsted and Lewis). CeO2 benefited from the addition of alkali (Na) or alkaline earth metals (Mg, Ca) by producing unsaturated alcohols.
Cronauer, Donald C.,Góra-Marek, Kinga,Garcia, Richard,Gnanamani, Muthu Kumaran,Jacobs, Gary,Kropf, A. Jeremy,Marshall, Christopher L.
(2020/07/10)

Vanadium Oxide-Nitride Composites for Catalytic Oxidative C?C Bond Cleavage of Cyclohexanol into Lactones with Dioxygen
Selective catalytic oxidative C?C bond cleavage with dioxygen is useful and challenging to prepare oxygenated fine chemicals. Herein we fabricated vanadium oxide–nitride composites as catalysts via a facile thermal treatment process, and the surface composition could be tuned by the thermal treatment temperature, which could affect catalytic oxidation of cyclohexanol significantly. By using such a V?N?C composite prepared at 500 °C, cyclohexanol could be selectively oxidized with dioxygen into lactones including δ-valerolactone and γ-butyrolactone, rather than common dicarboxylic acids. Cyclohexanone and 2-cyclohexen-1-one were verified as two key intermediates. V3+ species in the form of vanadium nitride and vanadium (III) oxide were detected, and well dispersed on amorphous carbon with a low degree of graphitization. These findings will provide a reference for catalytic oxidative C?C bond cleavage with molecular oxygen under mild reaction conditions.
Xiao, Chuhong,Du, Zhongtian,Li, Shaojie,Zhao, Yanbin,Liang, Changhai
p. 3650 - 3655
(2020/06/02)

Hydrogenolysis of tetrahydrofuran-2-carboxylic acid over tungsten-modified rhodium catalyst
Catalysts for reduction of tetrahydrofuran-2-carboxylic acid (THFCA), which can be synthesized from furfural via oxidation and hydrogenation, were explored among the combinations of noble metal and reducible metal oxide supported on SiO2. Rh-WOx/SiO2 catalysts showed activity in C-O hydrogenolysis at 2-position of THFCA (to δ-valerolactone and 5-hydroxyvaleric acid) and higher yield ratio of these C-O hydrogenolysis products to carboxylic acid hydrogenation products than other bimetallic catalysts. The activity of Rh-WOx/SiO2 catalysts was highest at W/Rh = 0.25 mol/mol. XRD, TPR, CO adsorption and XAFS characterizations showed that the Rh-WOx/SiO2 (W/Rh = 0.25) catalyst contained Rh metal particles with surface modification with isolated W2+ oxide species. The mechanism that hydride-like species formed on Rh atom attacks the C atom at the α-position (2-position) of adsorbed carboxylate on W atom is proposed based on the similar kinetics and similar catalyst structure to Rh-MOx/SiO2 (M = Re, Mo) which is known to be active in THFA hydrogenolysis to 1,5-pentanediol.
Asano, Takehiro,Nakagawa, Yoshinao,Tamura, Masazumi,Tomishige, Keiichi
(2020/07/04)

ε-Caprolactone manufacture via efficient coupling Baeyer-Villiger oxidation with aerobic oxidation of alcohols
To avoid the use of peracids oxidant or highly concentrated hydrogen peroxide which is potentially hazardous and explosive, herein, a new route to ε-caprolactone was developed in which molecule oxygen was employed as the terminal oxidant. The commercial available N-hydroxyphthalimide and ammonium cerium nitrate were used as the key catalysts for the increased yield of ε-caprolactone. For instance, the selectivity of ε-caprolactone was obtained 92 % with 85 % conversion of cyclohexanone which was comparable to the strategies using highly concentrated hydrogen peroxide. The sacrificed alcohols were transformed into corresponding ketones which were also valuable chemicals. Furthermore, the efficiency of the alcohols was achieved to unprecedented 52 %. The Baeyer-Villiger oxidation of various other cycloalkanones was also examined. The substituent group effect on the efficiency of sacrificed alcohols was investigated in which weak electron-donating substituent induced nearly quantitative yield of ε-caprolactone. The reaction mechanism was studied with the help of electron paramagnetic resonance which indicated the existence of a radical pathway.
Du, Renfeng,Li, Haoran,Wang, Yongtao,Yao, Jia,Yuan, Haoran,Zhao, Chenxuan
(2020/04/27)

Ruthenium-Promoted Acceptorless and Oxidant-Free Lactone Synthesis in Aqueous Medium
Ruthenium-catalyzed formation of lactones from diols in aqueous medium has been demonstrated. 1,3,5-Triazaphosphaadamantane (PTA) included water-soluble ruthenium complexes [RuCl 2 (PPh 3)(2,6-Py-(CH 2 -PTA) 2 ]·2Br and [RuCl 2 (PPh 3) 2 (2-PyCH 2 PTA)]·Br in the presence of KOH were found to be efficient for the synthesis of lactones from diols. The reported synthetic protocol is green as it uses water as solvent, avoids the use of any hydrogen acceptor/oxidant, and produces hydrogen as the only side product. Mechanistic studies revealed that lactone formation involved aldehyde intermediate and followed dehydrogenative pathway.
Bhatia, Anita,Kannan, Muthukumar,Muthaiah, Senthilkumar
supporting information
p. 721 - 725
(2019/03/26)

Efficient acceptorless photo-dehydrogenation of alcohols and: N -heterocycles with binuclear platinum(ii) diphosphite complexes
Although photoredox catalysis employing Ru(ii) and Ir(iii) complexes as photocatalysts has emerged as a versatile tool for oxidative C-H functionalization under mild conditions, the need for additional reagents acting as electron donor/scavenger for completing the catalytic cycle undermines the practicability of this approach. Herein we demonstrate that photo-induced oxidative C-H functionalization can be catalysed with high product yields under oxygen-free and acceptorless conditions via inner-sphere atom abstraction by binuclear platinum(ii) diphosphite complexes. Both alcohols (51 examples), particularly the aliphatic ones, and saturated N-heterocycles (24 examples) can be efficiently dehydrogenated under light irradiation at room temperature. Regeneration of the photocatalyst by means of reductive elimination of dihydrogen from the in situ formed platinum(iii)-hydride species represents an alternative paradigm to the current approach in photoredox catalysis.
Zhong, Jian-Ji,To, Wai-Pong,Liu, Yungen,Lu, Wei,Che, Chi-Ming
p. 4883 - 4889
(2019/05/16)

Surface Modification of Two-Dimensional Metal–Organic Layers Creates Biomimetic Catalytic Microenvironments for Selective Oxidation
Microenvironments in enzymes play crucial roles in controlling the activities and selectivities of reaction centers. Herein we report the tuning of the catalytic microenvironments of metal–organic layers (MOLs), a two-dimensional version of metal–organic frameworks (MOFs) with thickness down to a monolayer, to control product selectivities. By modifying the secondary building units (SBUs) of MOLs with monocarboxylic acids, such as gluconic acid, we changed the hydrophobicity/hydrophilicity around the active sites and fine-tuned the selectivity in photocatalytic oxidation of tetrahydrofuran (THF) to exclusively afford butyrolactone (BTL), likely a result of prolonging the residence time of reaction intermediates in the hydrophilic microenvironment of catalytic centers. Our work highlights new opportunities in using functional MOLs as highly tunable and selective two-dimensional catalytic materials.
Shi, Wenjie,Cao, Lingyun,Zhang, Hua,Zhou, Xin,An, Bing,Lin, Zekai,Dai, Ruihan,Li, Jianfeng,Wang, Cheng,Lin, Wenbin
supporting information
p. 9704 - 9709
(2017/08/08)

Continuous Flow Chemo-Enzymatic Baeyer-Villiger Oxidation with Superactive and Extra-Stable Enzyme/Carbon Nanotube Catalyst: An Efficient Upgrade from Batch to Flow
Continuous flow chemo-enzymatic Baeyer-Villiger oxidation in the presence of exceptionally active Candida antarctica lipase B immobilized via simple physical adsorption on multiwalled carbon nanotubes has been investigated. The nanobiocatalyst was used to generate peracid in situ from ethyl acetate and 30 wt % aq. hydrogen peroxide as the primary oxidant. Application of the highly stable and active nanobiocatalyst in the Baeyer-Villiger oxidation of 2-methylcyclohexanone to 6-methyl-?-caprolactone after 8 h at 40 °C led to a high product yield (87%) and selectivity (>99%). Environmentally friendly ethyl acetate was applied as both solvent and the peracid precursor. To determine the most favorable reaction conditions, a series of experiments using various parameters was performed. The main contribution of this work is that it describes the first application of the nanobiocatalyst in a chemo-enzymatic Baeyer-Villiger oxidation in a flow system. Since the process was performed in a flow reactor, many improvements were achieved. First of all, substantially shorter reaction times as well as a significant increase in the product yield were obtained as compared to the batch process. Since peracids are unstable, a large increase in the safety of the process was demonstrated under mild conditions in this work. In summary, this work shows a particularly efficient upgrade in the studied processes by transfer from a batch to a flow system.
Szelwicka, Anna,Zawadzki, Przemys?aw,Sitko, Magdalena,Boncel, S?awomir,Czardybon, Wojciech,Chrobok, Anna
supporting information
p. 1386 - 1395
(2019/08/12)

Expanding the substrate scope of phenylacetone monooxygenase from Thermobifida fusca towards cyclohexanone by protein engineering
Baeyer-Villiger monooxygenases (BVMOs) convert ketones into lactones that have important applications in polymer synthesis. Here we report on expanding the substrate scope of a thermostable phenylacetone monooxygenase (PAMO) to cyclohexanone by using site-directed mutagenesis. Several new mutants were found to be active with cyclohexanone for which wild-type PAMO shows no activity. The best mutants could convert 10 mM cyclohexanone completely within 12 h, and their catalytic properties were characterized subsequently. In addition to cyclohexanone, several other cyclic ketones were also identified as substrate for the new evolved mutants. These results expand the biocatalytic toolbox for further feasible applications.
Yang, Guang,Cang, Ran,Shen, Li-Qun,Xue, Feng,Huang, He,Zhang, Zhi-Gang
p. 159 - 163
(2018/11/21)

Synthesis and catalytic properties of macroporous SiO2-coated CNT-sieve-composite-supported 12-tungstophosphoric acid catalysts with dual pore structure for the Baeyer–Villiger oxidation of cyclic ketones under microwave irradiation
Carbon nanotube sieves (CNTs-S) with a flutelike shape were synthesized by cutting and perforating using a chemical oxidation etching method. Using the obtained CNTs-S as a hard template, SiO2-coated CNTs-S dual pore structures (CNTs-S@SiO2) were formed. Finally, tungstophosphoric acid was supported on CNTs, CNTs-S, and CNTs-S@SiO2 matrices by the incipient wetness method to obtain the corresponding supported catalysts PW12/CNTs, PW12/CNTs-S, and PW12/CNTs-S@SiO2. The results showed that obtained 30%PW12/CNTs-S and 30%PW12/CNTs-S@SiO2 catalysts in 30 wt% dipping solution had the best catalytic performance for Baeyer–Villiger oxidation of cyclic ketones by H2O2. The conversion of cyclohexanone was 94% and 91%, respectively, in 5 min under microwave irradiation. Cyclopentanone and adamantanone approached quantitative conversion and the selectivity of corresponding lactones reached 100%. The dual pore structure catalyst showed very excellent cyclic stability.
Wei, Yuli,Yang, Zhiwang,Zhao, Guohu,Yang, Wu
p. 196 - 206
(2019/02/19)

Preparation method of 5- bromo-n-valeryl bromide
The invention relates to a preparing method of 5-bromine pivaloyl bromide normal, belonging to the field of synthesizing methods of compounds. The preparing method of the 5-bromine pivaloyl bromide normal comprises the following steps: (1) synthesis of a midbody I: adding raw materials, i.e. m-chloroperoxybenzoic acid and drying chloroform, into a reaction kettle, and slowly adding a drying chloroform solution containing raw material cyclopentanone at room temperature so as to obtain a crude product of the midbody I; (2) synthesis of a midbody II: adding the raw material midbody I, hydrobromicacid and sodium bromide into the reaction kettle, reacting to obtain the midbody II and directly carrying out the reaction of a next step without purification; (3) synthesis of the 5-bromine pivaloylbromide normal: adding triphenylphosphine and dichloromethane into the reaction kettle, reducing the temperature to about 0 DEG C, starting to slowly add a dichloromethane solution containing bromine, adding the raw material midbody II to react, and purifying to obtain a target product, i.e. the 5-bromine pivaloyl bromide normal. The prepared product prepared by the method has higher purity and ideal yield coefficient and is suitable for being applied to industrialized production.
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Paragraph 0017; 0019; 0020; 0028; 0030

(2019/12/25)

Selective hydrogenolysis of 2-furancarboxylic acid to 5-hydroxyvaleric acid derivatives over supported platinum catalysts
The conversion of 2-furancarboxylic acid (FCA), which is produced by oxidation of furfural, to 5-hydroxyvaleric acid (5-HVA) and its ester/lactone derivatives with H2 was investigated. Monometallic Pt catalysts were effective, and other noble metals were not effective due to the formation of ring-hydrogenation products. Supports and solvents had a small effect on the performance; however, Pt/Al2O3 was the best catalyst and short chain alcohols such as methanol were better solvents. The optimum reaction temperature was about 373 K, and at higher temperature the catalyst was drastically deactivated by deposition of organic materials on the catalyst. The highest yield of target products (5-HVA, δ-valerolactone (DVL), and methyl 5-hydroxyvalerate) was 62%, mainly obtained as methyl 5-hydroxyvalerate (55% yield). The byproducts were mainly ring-hydrogenation compounds (tetrahydrofuran-2-carboxylic acid and its ester) and undetected ones (loss of carbon balance). The catalyst was gradually deactivated during reuses even at a reaction temperature of 373 K; however, the catalytic activity was recovered by calcination at 573 K. The reactions of various related substrates were carried out, and it was found that the O-C bond in the O-CC structure (1,2,3-position of the furan ring) is dissociated before CC hydrogenation while the presence and position of the carboxyl group (or methoxy carbonyl group) much affect the reactivity.
Asano, Takehiro,Takagi, Hiroshi,Nakagawa, Yoshinao,Tamura, Masazumi,Tomishige, Keiichi
supporting information
p. 6133 - 6145
(2019/11/20)

Synthesis of vinca alkaloid–triphenylphosphine derivatives having potential antitumor effect
The successful therapy of cancer is still unresolved. For that reason enormous efforts are being made to increase the effectiveness of anticancer drugs and reduce their side effects at least. An important approach to the development of selective molecules is the synthesis of drug conjugates, also called as “hybrids”. Taking this into consideration two Vinca alkaloid derivatives conjugated with triphenylphosphine have been synthetized. The incorporation of the mentioned two pharmacophores in the same molecule could amplify the evolving cumulative antineoplastic impact and/or counterbalance the side effects. Thus a development of hybrid anticancer molecules has been started by synthesis of Vinca alkaloid–triphenylphosphine conjugates, which could have higher efficacies and safety profiles than the present drugs available in market.
Keglevich, András,Szigetvári, áron,Dékány, Miklós,Szántay Jr, Csaba,Keglevich, Péter,Hazai, László
p. 606 - 609
(2019/06/20)

Method for preparing lactone compound by cycloalkane compound through oxidation
The invention discloses a method for preparing a lactone compound by a cycloalkane compound through oxidation. The method comprises the following steps of using the cycloalkane compound as the raw material, and further oxidizing by a catalysis system under the oxygen-containing atmosphere, so as to obtain the lactone compound, wherein the catalysis system comprises a catalyst and an additive; thecatalyst is selected from a cyclic organic nitrogen and oxygen free radical precursor in formulas (I), (II), (III) and (IV); in the formula, R1, R2 and R3 are independently selected from hydrogen atom, alkyl, cycloalkyl, aryl, heterocycle, hydroxyl, nitryl, or halogen, or at least two of R1, R2 and R3 form loops; the additive is selected from an aldehyde compound. The preparation method has the advantages that the corresponding lactone is prepared by the cycloalkane compound through a one-step method; the conditions are mild, the safety is high, and the metal catalytic oxidization is avoided;the selectivity of the target product, namely the lactone compound, is high. The formulae are shown in the description.
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Paragraph 0064; 0065; 0116-0119

(2019/02/04)

Selective One-Step Aerobic Oxidation of Cyclohexane to ?-Caprolactone Mediated by N-Hydroxyphthalimide (NHPI)
The selective one-step aerobic oxidation of cyclohexane to ?-caprolactone was achieved in the presence of N-hydroxyphthalimide (NHPI) and aldehyde under mild conditions. Remarkably, 12 % of cyclohexane was converted with a selectivity of 77 % of ?-caprolactone and 15 % of KA oil. Control experiments indicated that NHPI accelerated the oxidation of aldehydes and peroxy radicals generated from aldehydes in situ were the key intermediates in the period of CH bond activation. 2,2,6,6-Tetramethylpiperidine 1-oxyl (TEMPO) addition and a series of m-chloroperoxybenzoic acid (m-CPBA) oxidation experiments showed that the oxidation proceeded via a complex radical chain mechanism.
Wang, Lingyao,Zhang, Yuanbin,Du, Renfeng,Yuan, Haoran,Wang, Yongtao,Yao, Jia,Li, Haoran
p. 2260 - 2264
(2019/04/10)

A process for manufacturing a δ - e lactone method (by machine translation)
The invention provides a method for manufacturing δ - e lactone of the new method. The method comprises: 1) type (I) acetic acid alkyl esters with epichlorohydrin undergo nucleophilic substitution reaction, of formula (III) 4, 5 - epoxy valeric acid alkyl ester; 2) step 1) of formula (III) of 4, 5 - epoxy valeric acid alkyl ester hydrogenation reaction of formula (IV) 5 - hydroxy valeric acid alkyl ester; 3) steps 2) of formula (IV) of the 5 - hydroxy valeric acid alkyl ester generate the cyclization reaction generating δ - e lactone. The method of the invention total reaction yield up to 95% or more. The method the raw material is cheap, small pollution to the environment, mild reaction conditions, low cost, high yield of products to be easily purified, is suitable for industrial production. (by machine translation)
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Paragraph 0060; 0066-0068; 0078-0080; 0100; 0101

(2018/05/30)

On the Use of Polyelectrolytes and Polymediators in Organic Electrosynthesis
Although organic electrosynthesis is generally considered to be a green method, the necessity for excess amounts of supporting electrolyte constitutes a severe drawback. Furthermore, the employment of redox mediators results in an additional separation problem. In this context, we have explored the applicability of soluble polyelectrolytes and polymediators with the TEMPO-mediated transformation of alcohols into carbonyl compounds as a test reaction. Catalyst benchmarking based on cyclic voltammetry studies indicated that the redox-active polymer can compete with molecularly defined TEMPO species. Alcohol oxidation was also highly efficient on a preparative scale, and our polymer-based approach allowed for the separation of both mediator and supporting electrolyte in a single membrane filtration step. Moreover, we have shown that both components can be reused multiple times.
Schille, Benjamin,Giltzau, Niels Ole,Francke, Robert
supporting information
p. 422 - 426
(2018/02/21)

Base-Free and Acceptorless Dehydrogenation of Alcohols Catalyzed by an Iridium Complex Stabilized by a N, N, N-Osmaligand
The preparation of a N,N,N-osmaligand, its coordination to iridium to afford an efficient catalyst precursor, and the catalytic activity of the latter in dehydrogenation reactions of hydrogen carriers based on alcohols are reported. Complex OsH2Cl2(PiPr3)2 (1) reacts with 3-(2-pyridyl)pyrazol to give the osmium(II) complex 2H, which contains an acidic hydrogen atom. Deprotonation of the latter by the bridging methoxy groups of the dimer [Ir(μ-OMe)(n4-COD)]2 (COD = 1,5-cyclooctadiene) leads to Ir(2)( n 4-COD) (3), where osmaligand 2 has a free-nitrogen atom. Iridium complex 3 catalyzes the dehydrogenation of secondary and primary alcohols to ketones and aldehydes or esters, respectively, and the dehydrogenation of diols to lactones. Cyclooctatriene is detected during the catalysis by GC-MS, suggesting that the true catalyst of the reactions is a dihydride IrH2(2)-species with osmaligand 2 acting as N,N,N-pincer. The presence of a phenyl group in the substrates favors the catalytic processes. The dehydrogenative homocoupling of primary alcohols to esters appears to take place via the transitory formation of hemiacetals.
Alabau, Roberto G.,Esteruelas, Miguel A.,Martínez, Antonio,Oliván, Montserrat,O?ate, Enrique
p. 2732 - 2740
(2018/09/10)

Cobalt-entrenched N-, O-, and S-tridoped carbons as efficient multifunctional sustainable catalysts for base-free selective oxidative esterification of alcohols
We report the synthesis of sustainable and reusable non-noble transition-metal (cobalt) nanocatalysts containing N-, O-, and S-tridoped carbon nanotube (Co@NOSC) composites. The expensive and benign carrageenan served as the source of carbon, oxygen, and sulfur, whereas urea served as the nitrogen source. The material was prepared via direct mixing of precursors and freeze-drying followed by carbonization under nitrogen at 900 °C. Co@NOSC catalysts comprising a Co inner core and outer electron-rich heteroatom-doped carbon shell were thoroughly characterized using various techniques, namely, TEM, HRTEM, STEM elemental mapping, XPS, BET, and ICP-MS. The utility of the Co@NOSC catalyst was explored for base-free selective oxidative esterification of alcohols to the corresponding esters under mild reaction conditions; excellent conversions (up to 97%) and selectivities (up to 99%) were discerned. Furthermore, the substrate scope was explored for the cross-esterification of benzyl alcohol with long-chain alcohols (up to 98%) and lactonization of diols (up to 68%). The heterogeneous nature and stability of the catalyst facilitated by its ease of separation for long-term performance and recycling studies showed that the catalyst was robust and remained active even after six recycling experiments. EPR measurements were performed to deduce the reaction mechanism in the presence of POBN (α-(4-pyridyl-1-oxide)-N-tert-butylnitrone) as a spin-trapping agent, which confirmed the formation of CH2OH radicals and H radicals, wherein the solvent plays an active role in a nonconventional manner. A plausible mechanism was proposed for the oxidative esterification of alcohols on the basis of EPR findings. The presence of a cobalt core along with cobalt oxide and the electron-rich N-, O-, and S-doped carbon shell displayed synergistic effects to afford good to excellent yields of products.
Nandan, Devaki,Zoppellaro, Giorgio,Med?ík, Ivo,Aparicio, Claudia,Kumar, Pawan,Petr, Martin,Tomanec, Ond?ej,Gawande, Manoj B.,Varma, Rajender S.,Zbo?il, Radek
p. 3542 - 3556
(2018/08/07)

N-Hydroxyphthalimide (NHPI) Promoted Aerobic Baeyer-Villiger Oxidation in the Presence of Aldehydes
Metal-free aerobic Baeyer-Villiger (BV) oxidation of ketones to lactones or esters in the presence of aldehydes promoted by N-hydroxyphthalimide (NHPI) has been developed. The reaction proceeded under mild conditions with excellent selectivity and high yields. Compared with the methods that use metal complexes as catalysts, this strategy not only showed good environmental advantages, but also increased aldehyde efficiency up to 84 %. Control experiments indicated that NHPI accelerated the oxidation of aldehydes to peroxy acids but did not improve the BV oxidation while peroxy acids were already generated. Peroxy acids generated from aldehydes in situ were the key intermediates, and the phthalimide-N-oxyl radical (PINO) contributed to high aldehyde efficiency by stabilizing the radical species, which are necessary for the chain propagation reactions. This study may offer some useful strategies for new transition metal-free catalytic aerobic oxidation reactions in which aldehydes act as sacrificial agents.
Wang, Lingyao,Wang, Yongtao,Du, Renfeng,Dao, Rina,Yuan, Haoran,Liang, Cheng,Yao, Jia,Li, Haoran
p. 4961 - 4966
(2018/10/02)

1,1,2,2-Tetrahydroperoxy-1,2-Diphenylethane: An efficient and high oxygen content oxidant in various oxidative reactions
Several oxidative approaches namely thiocyanation of aromatic compounds, epoxidation of alkenes, amidation of aromatic aldehydes, epoxidation of α β-unsaturated ketones, oxidation of sulfides to sulfoxides and sulfones, bayer-villeger reaction, bromination and iodation of aniline and phenol derivatives oxidative esterification, oxidation of pyridines and oxidation of secondary, allylic and benzyllic alcohols were carried out using 1,1,2,2-Tetrahydroperoxy-1,2-Diphenylethane as the potential solid oxidant which can be stored for several months without any loss in its activity. All of the procedures were accomplished via mild reaction conditions and the products were afforded in high yields and short reaction times.
Khosravi, Kaveh,Naserifar, Shirin
supporting information
p. 6584 - 6592
(2018/10/05)

Baeyer-Villiger oxidation of cyclopentanone over zeolite Y entrapped transition metal-Schiff base complexes
Transition metal [M?=?VO (IV) and/or Cu (II)] complexes with Schiff base ligand, (Z)-2-((2-hydroxybenzylideneamino)phenol (H2L) have been entrapped in the super cages of zeolite-Y by Flexible Ligand Method. Synthesized materials have been characterized by preferential physico-chemical techniques such as inductively coupled plasma optical emission spectroscopy (ICP-OES), elemental analyses (CHN), fourier transmission infrared spectroscopy (FTIR), electronic and UV-reflectance spectra, Brunauer–Emmett–Teller (BET) surface area measurements, scanning electron micrographs (SEMs), X-ray diffraction patterns (XRD) and thermogravimetric analysis (TGA). The catalytic competence of zeolite-Y entrapped transition metal complexes was examined in Baeyer-Villiger (BV) oxidation of cyclopentanone using 30% H2O2 as an oxidant beside neat complexes to check the aptitude of heterogeneous catalysis over the homogeneous system. The effect of experimental variables such as mole ratio of substrate to an oxidant, amount of catalyst, reaction time, varying oxidants and solvents on the conversion of cyclopentanone was also tested. Under the optimized reaction conditions, one of the zeolite-Y entrapped transition metal complex viz. [VO(L)H2O]-Y [where L?=?(Z)-2-((2-hydroxybenzylideneamino)phenol] was found to be a potential contender by providing 80.22% conversion of cyclopentanone (TON: 10479.42), and the selectivity towards δ-valerolactone was 83.56%.
Modi, Chetan K.,Solanki, Naresh,Vithalani, Ravi,Patel, Dikin
(2017/10/05)

Enhanced shape selective catalysis of mixed cyclic ketones in aerobic Baeyer-Villiger oxidation with magnetic Cu-Fe3O4 supported mesoporous silica microspheres
Various strategies have been developed to improve the conversion for the Baeyer-Villiger oxidation. However, the catalytic effects of the Baeyer-Villiger oxidation for the mixed ketones are rarely reported, though it is also important for the natural and industrial separation processes. In this report, magnetite Cu modified Fe3O4 supported mesoporous silica microspheres (Cu-Fe3O4@mSiO2) have been successfully synthesized by two step direct hydrothermal method (DHT). Over 99% of cyclohexanone conversion was obtained with mild air oxidation and benzaldehyde as sacrificing agent over Cu-Fe3O4@mSiO2. The catalytic system also shows higher conversion rates for small molecular ketones in the mixed ketone reactants, which was attributed to the enhanced mass transfer effect and Fe-Cu composite active sites in the magnetite mesoporous silica microspheres. The catalyst could be recycled for four times with similar catalytic performance, which shows enhanced shape selectivity in aerobic Baeyer-Villiger oxidations for mixed cyclic ketones.
Zheng, Chunming,Chang, Shubin,Yang, Chuanwu,Lian, Dongying,Ma, Chao,Zhang, Chunrong,Fan, Xiangrui,Xu, Shichao,Sun, Xiaohong
p. 2608 - 2616
(2018/04/23)

Efficient Baeyer–Villiger Oxidation Catalysed by Silver Nanoparticles Stabilized on Modified Montmorillonite
Abstract: Silver nanoparticles supported on modified montmorillonite clay (Ag-NPs@mont), were utilized as catalyst for the Baeyer–Villiger oxidation of various ketones with hydrogen peroxide as an oxidant under solvent free condition at room temperature. The modification of Montmorillonite K10 clay was carried out with HCl under controlled conditions for generating a high surface area porous matrix which acts as support for the in situ generation of Silver nanoparticles. The synthesized nanocomposite material was characterized by UV–Visible spectroscopy, powder XRD, SEM-EDX, TEM and N2 adsorption–desorption analysis. The catalyst can be recycled and reused several times without significant loss of their catalytic activity. Graphical Abstract: [Figure not available: see fulltext.].
Borah, Subrat Jyoti,Das, Diganta Kumar
p. 3669 - 3677
(2018/11/21)

Photocatalytic Synthesis of 1,3-Dioxacyclanes from Diols and Primary Alcohols Effected by a System FeCl3–NaNO2/O2(Air)
Diols and primary alcohols were subjected to the action of a system FeCl3–NaNO2/O2 (air) under mercury lamp irradiation to synthesize unsubstituted and 2-methyl-1,3-dioxacyclanes: 1,3-dioxolane, 1,3-dioxepane, 1,3-dioxocane, 2-methyl-1,3-dioxolane, 2-methyl-1,3-dioxepane, 2-methyl-1,3-dioxocane. The probable mechanism of the photocatalytic synthesis of 1,3-dioxacyclanes was described by an example of 2-methyl-1,3-dioxolane.
Makhmutov
p. 1710 - 1714
(2019/02/14)

Pentafluoroperbenzoic acid as the efficient reagent for Baeyer–Villiger oxidation of cyclic ketones
The Baeyer–Villiger oxidation of cyclic ketones with pentafluoroperbenzoic acid provides the corresponding lactones in 40–98% yields.
Khusnutdinov, Ravil I.,Egorova, Tatyana M.,Aminov, Rishat I.,Dzhemilev, Usein M.
p. 644 - 645
(2018/12/13)

Macrolactonization of Alkynyl Alcohol through Rh(I)/Yb(III) Catalysis
A catalytic macrolactonization through oxidative cyclization of alkynyl alcohol by synergistic transition-metal and Lewis-acid catalysis was developed. Because the alkynyl alcohol substrates involved in this method are different from the seco acids that are used in conventional macrolactonization methods, the current method provides a strategically distinct entry to macrolactones. In addition to the operational simplicity, this macrolactonization protocol proceeds at relatively high concentration, precluding the need for high dilution or slow addition procedures.
Zhang, Wen-Wen,Gao, Tao-Tao,Xu, Li-Jin,Li, Bi-Jie
supporting information
p. 6534 - 6538
(2018/10/20)

Dehydration of 1,5-Pentanediol over CeO2-MeOx Catalysts
The dehydration reaction of 1,5-pentanediol was performed over CeO2 and modified CeO2 (CeO2?MnOx, CeO2?ZnO, CeO2?MgO, CeO2?CaO, CeO2?Na2O) catalysts in a fixed-bed tubular reactor at 350 °C and an atmospheric pressure. The undoped CeO2 produced a mixture of the products containing mainly 4-penten-1-ol, 1-pentanol, cyclopentanol, cyclopentanone and tetrahydropyran-2-one from 1,5-pentanediol, while additions of MgO, MnOx, or ZnO to CeO2 was found to enhance the overall production rate of unsaturated alcohol. On the other hand, more basic metals like CaO or Na2O tend to decline the dehydration activity of CeO2. The porous structure of CeO2 did not change appreciably with the addition of metal oxides. Temperature programmed desorption of adsorbed CO2 on an activated catalyst suggest more CO2 remain on the catalyst surface, particularly CeO2?CaO and CeO2?Na2O indicating that fewer defect sites are only available for reaction. The defect sites or oxygen vacancy on CeO2 controls both activity and selectivity for the dehydration of 1,5-pentanediol.
Gnanamani, Muthu Kumaran,Martinelli, Michela,Badoga, Sandeep,Hopps, Shelley D.,Davis, Burtron H.
p. 4629 - 4635
(2018/09/21)

High-Cluster (Cu9) Cage Silsesquioxanes: Synthesis, Structure, and Catalytic Activity
Unusual high-cluster (Cu9) cage phenylsilsesquioxanes were obtained via complexation of in situ CuII,Na-silsesquioxane species formed with phenanthroline and neocuproine. In the first case, phenanthroline, acting as "a silent ligand" (not participating in the composition of the final product), favors the formation of an unprecedented cagelike phenylsilsesquioxane of Cu9Na6 nuclearity, 1. In the second case, neocuproine ligands withdraws two Cu ions from the metallasilsesquioxane matrix, producing two cationic fragments Cu+(neocuproine)2. The remaining metallasilsesquioxane is rearranged into an anionic cage of Cu9Na4 nuclearity, finalizing the formation of a specific ionic complex, 2. The impressive molecular architecture of both types of complexes, e.g., the presence of different (cyclic/acyclic) types of silsesquioxane ligands, was established by single-crystal X-ray diffraction studies. Compound 1 was revealed to be highly active in the oxidative amidation of benzylic alcohol and the catalyst loading could be reduced down to 100 ppm of Cu. Catalytic studies of compound 1 demonstrated its high activity in hydroperoxidation of alkanes with H2O2 and oxidation of alcohols to ketones with tert-BuOOH.
Astakhov, Grigorii S.,Bilyachenko, Alexey N.,Korlyukov, Alexander A.,Levitsky, Mikhail M.,Shul'Pina, Lidia S.,Bantreil, Xavier,Lamaty, Frédéric,Vologzhanina, Anna V.,Shubina, Elena S.,Dorovatovskii, Pavel V.,Nesterov, Dmytro S.,Pombeiro, Armando J. L.,Shul'Pin, Georgiy B.
supporting information
p. 11524 - 11529
(2018/09/13)

A CATALYST COMPOSITION FOR A PRODUCTION PROCESS OF δ- LACTONE FROM CARBON DIOXIDE AND 1,3-BUTADIENE
This present invention relates to a catalyst composition for a production process of δ-lactone from carbon dioxide and 1,3 -butadiene that can efficiently catalyze the synthesis reaction of δ-lactone with good selectivity of δ-lactone, wherein said catalyst composition comprising: a) palladium metal complexes as shown in structure (I) [Formula should be inserted here] wherein, R1, R2, R3 and R4 independently represents a group selected from a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, an amine group, or optionally an alkenyl group, an alkynyl group, a phenyl group, a benzyl group, or a cyclic hydrocarbon group comprising a hetero atom; and b) phosphorus compound selected from a phosphine group having a general formula [Formula should be inserted here], wherein R5 is selected from an alkyl group, a cycloalkyl group, or an aryl group.
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Page/Page column 9

(2018/07/29)

A colourful azulene-based protecting group for carboxylic acids
An intensely blue-coloured protecting group for carboxylic acids has been developed. The protecting group is introduced through a Steglich esterification that couples 6-(2-hydroxyethyl)azulene (AzulE) and the carboxylic acid substrate. Deprotection is effected under basic conditions by the addition of the amidine base DBU, whereupon cleavage occurs, accompanied by a colour change. A two-step deprotection methodology comprising activation with oxalyl chloride and deprotection with a very mild base was developed for use with base-sensitive substrates. The AzulE esters were found to be compatible with other commonly employed protecting groups – silyl ethers, MOM acetals – by studying their orthogonal and concomitant deprotections. The stability of the new protecting group towards various synthetic processes – oxidation, reduction, cross-coupling, olefination and treatment with base – provided the basis of a versatility profile. This indicated that AzulE esters are sensitive to strongly oxidising and basic agents while being compatible with reducing conditions and selected other reactions. The convenience of a highly coloured protecting group for tracking material (and avoiding loss of compound) through laboratory processes warrants further investigation of this and/or related species.
Bevan, Thomas W.,Francis-Taylor, James,Wong, Helena,Northcote, Peter T.,Harvey, Joanne E.
supporting information
p. 2942 - 2955
(2018/05/16)

Method for producing DVL (delta-valerolactone)
The invention provides a method for producing DVL (delta-valerolactone). The method comprises the steps as follows: 1) acetonitrile and acraldehyde are subjected to an addition reaction, and a reaction solution containing an intermediate product 5-formyl butylcyanide is obtained; 2) 5-formyl butylcyanide is obtained is obtained after the reaction solution in the step 1) is subjected to reduced pressure distillation and separation purification, 5-formyl butylcyanide is subjected to a hydrogenation reaction, and 5-hydroxyl butylcyanide is produced; 3) 5-hydroxyl butylcyanide obtained in step 2)is subjected to a self-alcoholysis cyclization reaction and DVL is obtained. The total reaction yield is up to 95% or above. Raw materials are cheap and easy to obtain, the method causes small environmental pollution, adopts mild reaction conditions and is high in yield, low in cost and suitable for industrial production, and the product is easy to purify.
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Paragraph 0015; 0049; 0059; 0067

(2018/05/16)

Dehydration of 1,5-Pentanediol over Na-Doped CeO2 Catalysts
The effects of CeO2 doped with Na on the dehydration of 1,5-pentanediol were studied by using a fixed-bed reactor at two different temperatures (350 and 400 °C) and atmospheric pressure. For characterization, BET surface area, hydrogen temperature-programmed reduction, CO2 temperature-programmed desorption, and diffuse reflectance infrared Fourier transform spectroscopy techniques were utilized. The conversion of the diol on CeO2 was found to depend on Na loading. The selectivity to the desired product (i.e., unsaturated alcohol) increased and the selectivity to undesired products (i.e., tetrahydropyran, tetrahydropyran-2-one, cyclopentanol and cylopentanone) decreased with increasing Na content on CeO2. The basicity of hydroxyl groups or surface oxygen on CeO2 was altered with the addition of Na, and controlled the dehydration reaction pathway.
Gnanamani, Muthu Kumaran,Jacobs, Gary,Martinelli, Michela,Shafer, Wilson D.,Hopps, Shelley D.,Thomas, Gerald A.,Davis, Burtron H.
p. 1148 - 1154
(2018/02/12)

Method for preparing lactone by ion-catalyzed intramolecular cyclization of diols
The invention relates to a method for performing catalytic oxidative intramolecular cyclization of diols to obtain lactone under a mild condition by using metal iron salt as a catalyst and organic small molecular nitroxide free radicals as a cocatalyst. The method comprises the following steps: using aromatic diols and aliphatic diols with different substituents as substrates, using the metal iron salt as the catalyst, using the organic small molecular nitroxide free radicals as the cocatalyst, using air as an oxidant, and performing a catalytic oxidative reaction of the diols in a non-halogen solvent under the mild condition to obtain the lactone. A catalytic system adopted by the invention can overcome various defects of the conventional catalyst, and an iron catalyst system which is cheap, easy to obtain, non-toxic and high in activity is used; economical, safe and environment-friendly air is used as the oxidant; the reaction can be performed under a room temperature condition; the catalytic system has few components, and a ligand or an alkali compound is not required to be additionally added; the reaction has the advantages of easy operation, high catalytic efficiency, easy product separation and the like; the method has a very mild requirement on the reaction condition and has good research and application prospects.
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Paragraph 0030; 0031

(2017/08/29)

Oxidation of terminal diols using an oxoammonium salt: A systematic study
A systematic study of the oxidation of a range of terminal diols is reported, employing the oxoammonium salt 4-acetamido-2,2,6,6-tetramethylpiperidine-1-oxoammonium tetrafluoroborate (4-NHAc-TEMPO+ BF4-) as the oxidant. For substrates bearing a hydrocarbon chain of seven carbon atoms or more, the sole product is the dialdehyde. A series of post-oxidation reactions have been performed showing that the product mixture resulting from the oxidation step can be taken on directly to a subsequent transformation. For diols containing four to six carbon atoms, the lactone product is the major product upon oxidation. In the case of 1,2-ethanediol and 1,3-propanediol, when using a 1 : 0.5 stoichiometric ratio of substrate to oxidant, the corresponding monoaldehyde is formed which reacts rapidly with further diol to yield the acetal product. This is of particular synthetic value given both the difficulty of their preparation using other approaches and also their potential application in further reaction chemistry.
Miller, Shelli A.,Bobbitt, James M.,Leadbeater, Nicholas E.
supporting information
p. 2817 - 2822
(2017/04/04)

Synthesis of Cyclic Imides by Acceptorless Dehydrogenative Coupling of Diols and Amines Catalyzed by a Manganese Pincer Complex
The first example of base-metal-catalyzed dehydrogenative coupling of diols and amines to form cyclic imides is reported. The reaction is catalyzed by a pincer complex of the earth abundant manganese and forms hydrogen gas as the sole byproduct, making the overall process atom economical and environmentally benign.
Espinosa-Jalapa, Noel Angel,Kumar, Amit,Leitus, Gregory,Diskin-Posner, Yael,Milstein, David
supporting information
p. 11722 - 11725
(2017/09/07)

MANGANESE BASED COMPLEXES AND USES THEREOF FOR HOMOGENEOUS CATALYSIS
The present invention relates to novel manganese complexes and their use, inter alia, for homogeneous catalysis in (1) the preparation of imine by dehydrogenative coupling of an alcohol and amine; (2) C-C coupling in Michael addition reaction using nitriles as Michael donors; (3) dehydrogenative coupling of alcohols to give esters and hydrogen gas (4) hydrogenation of esters to form alcohols (including hydrogenation of cyclic esters (lactones) or cyclic di-esters (di- lactones), or polyesters); (5) hydrogenation of amides (including cyclic dipeptides, lactams, diamide, polypeptides and polyamides) to alcohols and amines (or diamine); (6) hydrogenation of organic carbonates (including polycarbonates) to alcohols or hydrogenation of carbamates (including polycarbamates) or urea derivatives to alcohols and amines; (7) dehydrogenation of secondary alcohols to ketones; (8) amidation of esters (i.e., synthesis of amides from esters and amines); (9) acylation of alcohols using esters; (10) coupling of alcohols with water and a base to form carboxylic acids; and (11) preparation of amino acids or their salts by coupling of amino alcohols with water and a base. (12) preparation of amides (including formamides, cyclic dipeptides, diamide, lactams, polypeptides and polyamides) by dehydrogenative coupling of alcohols and amines; (13) preparation of imides from diols.
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Paragraph 00386

(2017/09/05)

Scalable, Electrochemical Oxidation of Unactivated C-H Bonds
A practical electrochemical oxidation of unactivated C-H bonds is presented. This reaction utilizes a simple redox mediator, quinuclidine, with inexpensive carbon and nickel electrodes to selectively functionalize "deep-seated" methylene and methine moieties. The process exhibits a broad scope and good functional group compatibility. The scalability, as illustrated by a 50 g scale oxidation of sclareolide, bodes well for immediate and widespread adoption.
Kawamata, Yu,Yan, Ming,Liu, Zhiqing,Bao, Deng-Hui,Chen, Jinshan,Starr, Jeremy T.,Baran, Phil S.
supporting information
p. 7448 - 7451
(2017/06/13)

Fluorinated Porous Conjugated Polyporphyrins through Direct C?H Arylation Polycondensation: Preparation, Porosity, and Use as Heterogeneous Catalysts for Baeyer–Villiger Oxidation
By considering the high reactivity of fluorinated iron–porphyrin and good stability of porphyrin-based porous polymers, fluorinated iron–porphyrin conjugated porous polymers (FPOP-3–6) were synthesized through direct C?H arylation polymerization. The obtained materials are chemically and thermally stable, of which FPOP-3 exhibits the highest Brunauer–Emmett–Teller specific surface area (about 840 m2 g?1). For functional studies of the obtained polymers as heterogeneous catalysts, catalytic transformation of cycloketones into lactones by oxygen through Baeyer–Villiger oxidation was used as a model reaction. Fluorinated phenyl substituents of the iron–porphyrin not only are beneficial to the conversion, but also can stabilize the porphyrin to resist catalyst breakdown. The polymer FPOP-3, with high porosity, exhibits the best catalytic efficiency and recycling effect. The recovered catalyst also shows good catalytic activities after recycling three times with a small loss in yield.
Cao, Qiang,Yin, Qing,Chen, Qi,Dong, Zhi-Bing,Han, Bao-Hang
p. 9831 - 9837
(2017/07/25)