cas 76-09-5, Pinacol | Articles data

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Reductive coupling of phthalic anhydrides with aliphatic ketones by low-valent titanium: Unusual two-to-one coupling for preparation of 3,3-disubstituted phthalides
The reductive coupling of phthalic anhydrides with acetone by Zn-TiCl4 in THF gave two-to-one and one-to-one coupled products. The coupled products were transformed to 3,3-diisopropyl-, 3-isopropylidene-, and 3-isopropylphthalides. In addition, the reductive coupling of phthalic anhydrides with acetonylacetone by Zn-TiCl4 in THF gave 3-spirocyclopentanylphtalides stereoselectively.
Kise, Naoki,Yamamoto, Shota,Sakurai, Toshihiko
(2020)
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Deactivation and Regeneration of NaTaO3 Photocatalyst in Cooperating Dehydrogenation Coupling of Isopropanol and Hydrogenation Coupling of Acetone Reaction System
Photocatalyst activity is influenced by many factors, such as adsorption of by-products, runoff of surface hydroxyl groups and carriers. In this study, a simple and efficient photocatalyst regeneration method was developed. Results indicated that NaTaO3 photocatalyst lost its photoactivity after three cycles of reaction that involves coupling of isopropanol and hydrogenation coupling of acetone reaction system. Runoff of Na on the surface was the main reason for the deactivation of NaTaO3 photocatalyst. After hydrothermal treatment of the deactivated NaTaO3 with 10 m NaOH at 180°C for 12 h, its photocatalytic activity was restored to the original level. The photocatalytic activity remained stable even after 10 cycles.
Cao, Baoyue,Yu, Yan,Xu, Shan,Wang, Xiangting,Zhang, Li,Wang, Zhijian,Wang, Shumin,Zhang, Guochun
p. 466 - 471
(2018)
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Goldach
p. 1436,1439, 1444
(1931)
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Synthesis of Layered Carbonitrides from Biotic Molecules for Photoredox Transformations
The construction of layered covalent carbon nitride polymers based on tri-s-triazine units has been achieved by using nucleobases (adenine, guanine, cytosine, thymine and uracil) and urea to establish a two-dimensional semiconducting structure that allows band-gap engineering applications. This biomolecule-derived binary carbon nitride polymer enables the generation of energized charge carrier with light-irradiation to induce photoredox reactions for stable hydrogen production and heterogeneous organosynthesis of C?O, C?C, C?N and N?N bonds, which may enrich discussion on chemical reactions in prebiotic conditions by taking account of the photoredox function of conjugated carbonitride semiconductors that have long been considered to be stable HCN-derived organic macromolecules in space.
Yang, Can,Wang, Bo,Zhang, Linzhu,Yin, Ling,Wang, Xinchen
p. 6627 - 6631
(2017)
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Controlling Chemoselectivity of Catalytic Hydroboration with Light
The ability to selectively react one functional group in the presence of another underpins efficient reaction sequences. Despite many designer catalytic systems being reported for hydroboration reactions, which allow introduction of a functional handle fo
Bergamaschi, Enrico,Chen, Yi-Kai,Hohenadel, Melissa,Lunic, Danijela,McLean, Liam A.,Teskey, Christopher J.
supporting information

(2022/01/13)

Well-defined Cp*Co(III)-catalyzed Hydrogenation of Carbonates and Polycarbonates
We herein report the catalytic hydrogenation of carbonates and polycarbonates into their corresponding diols/alcohols using well-defined, air-stable, high-valent cobalt complexes. Several novel Cp*Co(III) complexes bearing N,O-chelation were isolated for the first time and structurally characterized by various spectroscopic techniques including single crystal X-ray crystallography. These novel Co(III) complexes have shown excellent catalytic activity to produce value added diols/alcohols from carbonate and polycarbonates through hydrogenation using molecular hydrogen as sole reductant or iPrOH as transfer hydrogenation source. To demonstrate the developed methodology's practical applicability, we have recycled the bisphenol A monomer from compact disc (CD) through hydrogenation under the established reaction conditions using phosphine-free, earth-abundant, air- and moisture-stable high-valent cobalt catalysts.
Dahiya, Pardeep,Gangwar, Manoj Kumar,Sundararaju, Basker
p. 934 - 939
(2020/12/15)

Protodeboronation of (Hetero)Arylboronic Esters: Direct versus Prehydrolytic Pathways and Self-/Auto-Catalysis
The kinetics and mechanism of the base-catalyzed hydrolysis (ArB(OR)2→ ArB(OH)2) and protodeboronation (ArB(OR)2→ ArH) of a series of boronic esters, encompassing eight different polyols and 10 polyfluoroaryl and heteroaryl moieties, have been investigated by in situ and stopped-flow NMR spectroscopy (19F,1H, and11B), pH-rate dependence, isotope entrainment,2H KIEs, and KS-DFT computations. The study reveals the phenomenological stability of boronic esters under basic aqueous-organic conditions to be highly nuanced. In contrast to common assumption, esterification does not necessarily impart greater stability compared to the corresponding boronic acid. Moreover, hydrolysis of the ester to the boronic acid can be a dominant component of the overall protodeboronation process, augmented by self-, auto-, and oxidative (phenolic) catalysis when the pH is close to the pKaof the boronic acid/ester.
Hayes, Hannah L. D.,Wei, Ran,Assante, Michele,Geogheghan, Katherine J.,Jin, Na,Tomasi, Simone,Noonan, Gary,Leach, Andrew G.,Lloyd-Jones, Guy C.
supporting information
p. 14814 - 14826
(2021/09/13)

Boronic, diboronic and boric acid esters of 1,8-naphthalenediol-synthesis, structure and formation of boronium salts
The 1,8-naphthalenediolate [1,8-O2C10H8] supported boronic and boric acid esters of general formula X-B(1,8-O2C10H8), where X = C6H5 (1a), C6F5 (2a), 3,4,5-F3-C6H2 (3a), 2,4,6-F3-C6H2 (4a), 2,6-F2-C6H3 (5a), 2,6-Cl2-C6H3 (6a), 2,4,6-Me3-C6H2 (7a), 2,6-(MeO)3-C6H3 (8a), Bun (9a), MeO (10a), OH (11a) and Cl (13a), were synthesized, NMR spectroscopically characterized, and the solid-state structures of 1a-5a, 8a and 10a determined by X-ray crystallography. The acceptor numbers of 1a-7a and 13a were determined and found to be similar to their catecholate analogues, R-Bcat, indicating similar Lewis acidities of these two classes of boronic acid esters. The reaction of B2(NMe2)4 with 1,8-naphthalenediol, followed by addition of HCl furnished the diboronic acid ester B2(1,8-O2C10H8)4 (16a) in ca. 70% yield. Cl-B(1,8-O2C10H8) (13a) was shown to react with OPEt3, DMAP, 1,10-phenanthroline and 2,2′-bipyridine, resp., to give the boronium salts [(Et3PO)2B(1,8-O2C10H8)]Cl (18a), [(DMAP)2B(1,8-O2C10H8)]Cl (22a), [(2,2′-bipyridine)B(1,8-O2C10H8)]Cl (23a) and [(1,10-phenanthroline)B(1,8-O2C10H8)]Cl (24a), which were characterized by NMR spectroscopy and X-ray crystallography.
Krempner, Clemens,Manankandayalage, Chamila P.,Unruh, Daniel K.
supporting information
p. 4834 - 4842
(2020/04/27)

GaN nanowires as a reusable photoredox catalyst for radical coupling of carbonyl under blacklight irradiation
Employing photo-energy to drive the desired chemical transformation has been a long pursued subject. The development of homogeneous photoredox catalysts in radical coupling reactions has been truly phenomenal, however, with apparent disadvantages such as the difficulty in separating the catalyst and the frequent requirement of scarce noble metals. We therefore envisioned the use of a hyper-stable III-V photosensitizing semiconductor with a tunable Fermi level and energy band as a readily isolable and recyclable heterogeneous photoredox catalyst for radical coupling reactions. Using the carbonyl coupling reaction as a proof-of-concept, herein, we report a photo-pinacol coupling reaction catalyzed by GaN nanowires under ambient light at room temperature with methanol as a solvent and sacrificial reagent. By simply tuning the dopant, the GaN nanowire shows significantly enhanced electronic properties. The catalyst showed excellent stability, reusability and functional tolerance. All reactions could be accomplished with a single piece of nanowire on Si-wafer. This journal is
Botton, Gianluigi,Cen, Yunen,Cheng, Shaobo,Li, Chao-Jun,Liu, Mingxin,Mi, Zetian,Rashid, Roksana T.,Tan, Lida
p. 7864 - 7870
(2020/08/19)

Oxidative Cleavage of Alkene C=C Bonds Using a Manganese Catalyzed Oxidation with H2O2 Combined with Periodate Oxidation
A one-pot multi-step method for the oxidative cleavage of alkenes to aldehydes/ketones under ambient conditions is described as an alternative to ozonolysis. The first step is a highly efficient manganese catalyzed epoxidation/cis-dihydroxylation of alkenes. This step is followed by an Fe(III) assisted ring opening of the epoxide (where necessary) to a 1,2-diol. Carbon–carbon bond cleavage is achieved by treatment of the diol with sodium periodate. The conditions used in each step are not only compatible with the subsequent step(s), but also provide for increased conversion compared to the equivalent reactions carried out on the isolated intermediate compounds. The described procedure allows for carbon–carbon bond cleavage in the presence of other alkenes, oxidation sensitive moieties and other functional groups; the mild conditions (r.t.) used in all three steps make this a viable general alternative to ozonolysis and especially for use under flow or continuous batch conditions.
Mecozzi, Francesco,Dong, Jia Jia,Angelone, Davide,Browne, Wesley R.,Eisink, Niek N. H. M.
supporting information
p. 7151 - 7158
(2019/11/16)

Preparation method of pinacol
The invention discloses a preparation method of pinacol. The method includes: adding a tin tetrachloride source solution into an acetone-isopropanol reaction solution, introducing argon under magneticstirring for 10min, turning on an ultraviolet lamp source, and starting photocatalyzed isopropanol dehydrogenation-acetone hydrogenation coupling reaction to prepare pinacol; controlling the reactiontemperature at 20-50DEG C and the reaction time at 5-36h; and conducting standing at low temperature, precipitating pinacol crystals, and performing filtering to obtain the product pinacol, and further recycling the filtrate. The method provided by the invention has the advantages of simple process, high selectivity, high activity, high yield, low cost, environmental friendliness and the like, and the purity of pinacol reaches 98%.
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Paragraph 0006; 0018-0047

(2020/01/12)

A convenient C–H functionalization platform for pyrroloiminoquinone alkaloid synthesis
Pyrroloiminoquinone alkaloids represent a structurally intriguing class of natural products that display an array of useful biological properties. Here, we present a versatile and scalable platform for the synthesis of this diverse family – and in particular the antitumor discorhabdins – built upon sequential selective C–H functionalization of tryptamine. The utility of this strategy is showcased through short formal syntheses of damirones A–C, makaluvamines D and I, and discorhadbin E. Additionally, we describe efforts to develop the first catalytic asymmetric entry to the discorhabdin subclass.
Smith, Myles W.,Falk, Isaac D.,Ikemoto, Hideya,Burns, Noah Z.
p. 3366 - 3370
(2019/05/17)

Remarkable Reactivity of Boron-Substituted Furans in the Diels-Alder Reactions with Maleic Anhydride
The reactivity of boron-substituted furans as dienes in the Diels-Alder reaction with maleic anhydride has been investigated. Gratifyingly, the furans with boryl substituents at C-3 gave the exo cycloadduct exclusively with excellent yields. In particular, the potassium trifluoroborate exhibited outstanding reactivity at room temperature. Theoretical calculations suggested that the trifluoroborate group is highly activating and also that the thermodynamics is the main factor that determines whether the products can be obtained efficiently or not.
Medrán, Noelia S.,Dezotti, Federico,Pellegrinet, Silvina C.
supporting information
p. 5068 - 5072
(2019/07/03)

Catalytic Hydrogenation of Cyclic Carbonates using Manganese Complexes
Catalytic hydrogenation of cyclic carbonates to diols and methanol was achieved using a molecular catalyst based on earth-abundant manganese. The complex [Mn(CO)2(Br)[HN(C2H4PiPr2)2] 1 comprising commercially available MACHO ligand is an effective pre-catalyst operating under relatively mild conditions (T=120 °C, p(H2)=30–60 bar). Upon activation with NaOtBu, the formation of coordinatively unsaturated complex [Mn(CO)2[N(C2H4PiPr2)2)] 5 was spectroscopically verified, which confirmed a kinetically competent intermediate. With the pre-activated complex, turnover numbers up to 620 and 400 were achieved for the formation of the diol and methanol, respectively. Stoichiometric reactions under catalytically relevant conditions provide insight into the stepwise reduction form the CO2 level in carbonates to methanol as final product.
Kaithal, Akash,H?lscher, Markus,Leitner, Walter
supporting information
p. 13449 - 13453
(2018/09/25)

The hydrolysis of epoxides catalyzed by inorganic ammonium salts in water: Kinetic evidence for hydrogen bond catalysis
Naturally-occurring inorganic ammonium ions have been recently reported as efficient catalysts for some organic reactions in water, which contributes to the understanding of the chemistry in some natural environments (soils, seawater, atmospheric aerosols, .) and biological systems, and is also potentially interesting for green chemistry as many of their salts are cheap and non-toxic. In this work, the effect of NH4+ ions on the hydrolysis of small epoxides in water was studied kinetically. The presence of NH4+ increased the hydrolysis rate by a factor of 6 to 25 compared to pure water and these catalytic effects were shown not to result from other ions, counter-ions or from acid or base catalysis, general or specific. The small amounts of amino alcohols produced in the reactions were identified as the actual catalysts by obtaining a strong acceleration of the reactions when adding these compounds directly to the epoxides in water. Replacing the amino alcohols by other strong hydrogen-bond donors, such as trifluoroethanol (TFE) or hexafluoroisopropanol (HFIP) gave the same results, demonstrating that the kinetics of these reactions was driven by hydrogen-bond catalysis. Because of the presence of many hydrogen-bond donors in natural environments (for instance amines and hydroxy-containing compounds), hydrogen-bond catalysis is likely to contribute to many reaction rates in these environments.
Nozière,Fache,Maxut,Fenet,Baudouin,Fine,Ferronato
p. 1583 - 1590
(2018/02/06)

A green and efficient photo-driven route for the selective oxidation of aqueous isopropanol solution to pinacol (C6) with hydrogen peroxide
Selective oxidation of alcohols to highly valued chemicals in a clean manner (e.g., with water as a solvent and O2 or H2O2 as the primary oxidant) is the subject of considerable research attention. This paper presents a simple and environmentally friendly approach for the selective oxidation of isopropanol to pinacol C6 (2,3-dimethyl-2,3-butanediol) in water with hydrogen peroxide (H2O2) through UV irradiation under mild conditions. A selectivity of 82-95% is achieved at H2O2 feeding rates below 4 mL h?1. The introduction of TiO2 nanotubes can further accelerate isopropanol conversion and enhance pinacol C6 formation. The highest formation rate of pinacol C6 and the highest conversion rate of isopropanol are 29.4 and 71.4 mmol h?1, respectively. The proposed strategy provides a green solution for the synthesis of aliphatic pinacol and offers a new design for the construction of C-C bonds with alphatic alcohol.
Li, Na,Yan, Wenjun,Zhang, Hongxia,Jia, Suping,Wang, Zhijian,Zheng, Jianfeng,Zhu, Zhenping
p. 2764 - 2768
(2017/04/03)

Enhanced solvent-free selective oxidation of cyclohexene to 1,2-cyclohexanediol by polyaniline@halloysite nanotubes
One-dimensional polyaniline@halloysite (PANI@HA) nanotubes with enhanced selective oxidation activity of cyclohexene are fabricated by employing aniline (ANI) chemical polymerization on halloysite nanotubes in situ. By facilely controlling the doping acid, acidity, and ANI/HA weight ratio during the fabrication, PANI with a controllable doping degree, redox state, and content is grown on halloysite nanotubes. The cyclohexene selective oxidation result shows that PANI@HA nanotubes are effective catalysts in a solvent-free reaction system with H2O2 as the oxidant, and their catalytic activity relies on the doping acid, acidity, and ANI/HA weight ratio in the fabrication. PANI@HA synthesized with HCl as a doping acid to condition the acidity at 1 M and 2.04 ANI/HA weight ratio (PANI@HA/1 M/2.04-HCl) demonstrates highest catalytic activity (98.17% conversion and 99.50% selectivity to 1,2-cyclohexanediol). The cyclohexene selective catalytic activity matches well with the PANI doping degree in PANI@HA. In addition, the optimal reaction condition is 20 mg catalyst, 2.5 mL H2O2, 70 °C, and 24 h. Furthermore, PANI@HA/1 M/2.04-HCl exhibits superior dihydroxylation activity toward 2,3-dimethyl-2-butene and cycling performance with 99.11% conversion and 96.92% selectivity to 1,2-cyclohexanediol after five cycles. The CV of PANI@HA indicates that the cyclohexene selective oxidation is attributed to a reversible redox reaction of PANI in PANI@HA for catalytic decomposition of H2O2.
Zhou, Tianzhu,Zhao, Yue,Han, Wenmei,Xie, Huazhong,Li, Cuiping,Yuan, Mingquan
supporting information
p. 18230 - 18241
(2017/09/08)

Synthesis, Characterization and Catalytic Application of Pyridine-Bridged N-Heterocyclic Carbene–Ruthenium Complexes in the Hydrogenation of Carbonates
A series of bulky pyridine-bridged NHC–Ru complexes have been rationally designed and synthesized; these exhibited very high catalytic activity in the hydrogenation of cyclic and linear carbonates under mild reaction conditions. In the presence of catalytic amounts of a weak base, a broad range of substrates with different ring size and steric bulk were well tolerated, providing methanol and the corresponding diols in excellent yields with a catalyst loading as low as 0.5 mol %.
Chen, Jiangbo,Zhu, Haibo,Chen, Jinjin,Le, Zhang-Gao,Tu, Tao
supporting information
p. 2809 - 2812
(2017/10/23)

Photocatalytic hydrogenation coupling of acetone into pinacol using formic acid as hydrogen source
We demonstrated photocatalytic hydrogenation coupling of acetone into 2,3-dimethyl-2,3-butanediol with formic acid as a hydrogen source. In this synergetic system, the conversion of acetone and formic acid was dramatically increased than that in the individual reaction system. Consequently, the selectivity of 2,3-dimethyl-2,3-butanediol was relatively high over that of NaTaO3 and Na2Ti3O7 photocatalysts. Additionally, in this acetoneformic acid reaction system, the presence of acetone can effectively restrain the generation of CO during the decomposition of formic acid.
Cao, Bao Y.,Xu, Shan,Ren, You L.,Yu, Yan,Guo, Jin Y.,Zhang, Li,Li, Na,Zhang, Guo C.,Zhou, Chun S.
p. 1773 - 1776
(2017/11/23)

Hydrogenative cyclization of levulinic acid into γ-valerolactone by photocatalytic intermolecular hydrogen transfer
The hydrogenative cyclization of levulinic acid (LA) into γ-valerolactone (GVL) is an attractive route toward the use of renewable bio-sources but it normally suffers from the consumption of H2. In this study, we report that an intermolecular hydrogen transfer from isopropanol to LA can be realized efficiently under photocatalytic conditions over gold-loaded TiO2 catalysts. In this manner, isopropanol is dehydrogenated as acetone and pinacol with the total selectivity of >99%, whereas LA is hydrogenated and cyclized as GVL with the selectivity of up to 85%. In this reaction process, the production of GVL is mediated with hydrogenated dehydration of LA into an acetyl propionyl radical, which is further hydrogenated and cyclized as GVL. This hydrogenation-dehydrogenation coupling process provides an atom-economical green way for the conversion of LA into GVL.
Zhang, Hongxia,Zhao, Min,Zhao, Tianjian,Li, Li,Zhu, Zhenping
p. 2296 - 2301
(2016/05/19)

Synthesis, crystal structure and hydrolysis of novel isomeric cage (P-C/P-O)-phosphoranes on the basis of 4,4,5,5-tetramethyl-2-(2-oxo-1,2-diphenylethoxy)-1,3,2-dioxaphospholane and hexafluoroacetone
The reaction of 4,4,5,5-tetramethyl-2-(2-oxo-1,2-diphenylethoxy)-1,3,2-dioxaphospholane with hexafluoroacetone leads to the simultaneous formation of regioisomeric cage (P-C/P-O)-phosphoranes, the structures of which are unequivocally confirmed by XRD. The rearrangement of the P-C-isomer to P-O-isomer with high stereoselectivity (>96%) takes place in methylene chloride solution with the retention of the phosphorus coordination. It was found that the stepwise hydrolysis of the P-O-isomer initially gives 2-(2,3-dihydroxy-1,2-diphenyl-3-trifluoromethyl-4,4,4-trifluorobutyloxy)-4,4,5,5-tetramethyl-2-oxo-1,3,2-dioxaphospholane as the only stereoisomer whose structure is also confirmed by XRD. Further hydrolysis of this compound leads to the formation of 2,3-dihydroxy-3-trifluoromethyl-4,4,4-trifluoro-1,2-diphenylbutylphosphate and pinacol, which forms the solvate in the crystal. Hydrolysis of the P-C-isomer yields 2-hydroxy-4,4,5,5-tetramethyl-2-oxo-1,3,2-dioxaphospholane, benzoin and hexafluoroisopropanol.
Khasiyatullina, Nadezhda R.,Mironov, Vladimir F.,Krivolapov, Dmitry B.,Mironova, Ekaterina V.,Gnezdilov, Oleg I.
p. 85745 - 85755
(2016/09/23)

Regioselective Cleavage of Electron-Rich Double Bonds in Dienes to Carbonyl Compounds with [Fe(OTf)2(mix-BPBP)] and a Combination of H2O2 and NaIO4
A method for the regioselective transformation of dienes to carbonyl compounds has been developed. Electron-rich olefins react selectively to yield valuable aldehydes and ketones. The method is based on the catalyst [Fe(OTf)2(mix-BPBP)] with an oxidant combination of H2O2 (1.0 equiv.) and NaIO4 (1.5 equiv.); it uses mild conditions and short reaction times, and it outperforms other olefin cleavage methodologies. The combination of an Fe-based catalyst, [Fe(OTf)2(mix-BPBP)], and the oxidants H2O2 and NaIO4 can discriminate between electronically different double bonds and oxidatively cleave the electron-rich bond in dienes to yield aldehydes and ketones in a regioselective manner. The reaction requires mild conditions (0-50 C) and short reaction times (70 min).
Spannring, Peter,Yazerski, Vital A.,Chen, Jianming,Otte, Matthias,Weckhuysen, Bert M.,Bruijnincx, Pieter C. A.,Klein Gebbink, Robertus J. M.
p. 3462 - 3466
(2015/08/06)

A facile synthesis of vicinal cis-diols from olefins catalyzed by in situ generated MnxOy nanoaggregates
A novel protocol for the practical and green synthesis of vicinal cis-diols from 10.0 mmol olefins by using 5.0 mmol KMnO4 as oxidant and 30.0 mmol H2O2 as co-oxidant is reported. The presented procedure is easy to carry out and enables the direct transformation of linear and cyclic alkenes to the corresponding vicinal cis-diols. The synthesis of vicinal cis-diols by dihydroxylation of olefins with a KMnO4/H2O2 system was catalyzed by in situ generated MnxOy nanoaggregates. The use of H2O2 as a co-oxidant is the key for the protocol to synthesize vicinal cis-diols in high yields, because it assists the oxidation of MnxOy nanoaggregates, which have an active role in the oxidation reaction medium.
Dalmizrak, Di?dem,G?ksu, Haydar,Gültekin, Mehmet Serdar
p. 20751 - 20755
(2015/03/18)

Comparison of photoreactions of flutamide in acetonitrile and 2-propanol solvents in the absence of cage-forming compounds
Flutamide(2-methyl-N-[4-nitro-3-(trifluoromethylphenyl)]propanamide) is a widely used anti-cancer drug. It has been reported that photodermatosis is occasionally induced when an individual taking flutamide is exposed to sunlight. In this study, we found that flutamide undergoes different photoreactions in two different solvents: acetonitrile and 2-propanol. The photo-induced nitro-nitrite rearrangement was the predominant reaction when a flutamide solution in acetonitrile was irradiated with UV light, and phenoxy radicals and nitrogen monoxide were generated. The nitrogen monoxide recombined with the phenoxy radical at the ortho position and was oxidized by the oxygen dissolved in the acetonitrile. The final product was o-nitrophenol derivative. However, the photoreduction of the nitro group followed by solvolysis of the trifluoromethyl group was observed when a flutamide solution in 2-propanol was irradiated with UV light. The three fluorine atoms in the trifluoromethyl group were eliminated by being nucleophilically attacked by a solvent molecule, resulting in an ester bond with 2-propanol being formed.
Watanabe, Yurie,Fukuyoshi, Shuichi,Oda, Akifumi
p. 55 - 61
(2015/02/19)

An Aza-Cope Reactivity-Based Fluorescent Probe for Imaging Formaldehyde in Living Cells
Formaldehyde (FA) is a reactive carbonyl species (RCS) produced in living systems that has been implicated in epigenetics as well as in the pathologies of various cancers, diabetes, and heart, liver, and neurodegenerative diseases. Traditional methods for biological FA detection rely on sample destruction and/or extensive processing, resulting in a loss of spatiotemporal information. To help address this technological gap, we present the design, synthesis, and biological evaluation of a fluorescent probe for live-cell FA imaging that relies on a FA-induced aza-Cope rearrangement. Formaldehyde probe-1 (FAP-1) is capable of detecting physiologically relevant concentrations of FA in aqueous buffer and in live cells with high selectivity over potentially competing biological analytes. Moreover, FAP-1 can visualize endogenous FA produced by lysine-specific demethylase 1 in a breast cancer cell model, presaging the potential utility of this chemical approach to probe RCS biology.
Brewer, Thomas F.,Chang, Christopher J.
supporting information
p. 10886 - 10889
(2015/09/15)

Deciphering Photoluminescence Dynamics and Reactivity of the Luminescent Metal-Metal-Bonded Excited State of a Binuclear Gold(I) Phosphine Complex Containing Open Coordination Sites
Luminescent metal complexes having open coordination sites hold promise in the design of sensory materials and photocatalysts. As a prototype example, [Au2(dcpm)2)]2+ (dcpm = bis(dicyclohexylphosphanyl) is known for its intriguing environmental sensitive photoluminescence. By integrating a range of complementary ultrafast time-resolved spectroscopy to interrogate the excited state dynamics, this study uncovers that the events occurring in extremely rapid timescales and which are modulated strongly by environmental conditions play a pivotal role in the luminescence behavior and photochemical outcomes. Formed independent of the phase and solvent property within 0.15 ps, the metal-metal bonded 35dσ6pσ state is highly reactive possessing strong propensity toward increasing coordination number at AuI center, and with 510 ps lifetime in dichloromethane is able to mediate light induced C-X bond cleavage.
Ma, Chensheng,Chan, Chris Tsz-Leung,To, Wai-Pong,Kwok, Wai-Ming,Che, Chi-Ming
supporting information
p. 13888 - 13893
(2015/09/28)

A Bioorthogonal Reaction of N-Oxide and Boron Reagents
The development of bioorthogonal reactions has classically focused on bond-forming ligation reactions. In this report, we seek to expand the functional repertoire of such transformations by introducing a new bond-cleaving reaction between N-oxide and boron reagents. The reaction features a large dynamic range of reactivity, showcasing second-order rate constants as high as 2.3×103 M-1 s-1 using diboron reaction partners. Diboron reagents display minimal cell toxicity at millimolar concentrations, penetrate cell membranes, and effectively reduce N-oxides inside mammalian cells. This new bioorthogonal process based on miniscule components is thus well-suited for activating molecules within cells under chemical control. Furthermore, we demonstrate that the metabolic diversity of nature enables the use of naturally occurring functional groups that display inherent biocompatibility alongside abiotic components for organism-specific applications. The bond-cleaving reaction between N-oxide and diboron reagents features second-order rate constants as high as 2.3×103 M-1 s-1. Diboron reagents display minimal cell toxicity at millimolar concentrations, penetrate cell membranes, and reduce N-oxides inside mammalian cells. This new bioorthogonal reaction is thus well-suited for chemically activating molecules within cells.
Kim, Justin,Bertozzi, Carolyn R.
supporting information
p. 15777 - 15781
(2016/01/29)

Cooperative dehydrogenation coupling of isopropanol and hydrogenation coupling of acetone over a sodium tantalate photocatalyst
Photocatalytic organic syntheses are often limited by their low system efficiency and product selectivity. We demonstrate herein that intermolecular hydrogen transfer from isopropanol to acetone can be achieved efficiently on the surfaces of NaTaO3 photocatalysts, on which 2-hydroxyisopropyl radicals are produced selectively from both oxidation and reduction half-reactions and then coupled to form 2,3-dimethyl-2,3-butanediol. Such a process effectively increases the total reaction efficiency. We also found that the two half-reactions occur at different crystal facets and display a remarkably promotive interaction, which dramatically speeds up the reactions by one order of magnitude and significantly restrains side reactions. The sodium ions on the NaTaO3 surfaces play an important role in the promotive effect, likely facilitating the proton transfer between the oxidation and reduction sites. These factors make the production rate of 2,3-dimethyl-2,3- butanediol reach a very high level (10.87 mmol g-1 h-1), emphasizing the potential of photocatalytic hydrogenation and dehydrogenation in improving system efficiency of photocatalytic organic syntheses. Double couple: Dehydrogenation coupling of isopropanol and hydrogenation coupling of acetone can be performed simultaneously on a single NaTaO3 photocatalyst through intermolecular hydrogen transfer and display a remarkable promotive interaction, which speeds the reactions by one order of magnitude and restrains side reactions. CB=conduction band, VB=valence band.
Cao, Baoyue,Zhang, Jian,Zhao, Jianghong,Wang, Zhijian,Yang, Pengju,Zhang, Hongxia,Li, Li,Zhu, Zhenping
p. 1673 - 1678
(2014/06/24)

Direct borylation of primary C-H bonds in functionalized molecules by palladium catalysis
Organoborane compounds are among the most commonly employed intermediates in organic synthesis and serve as crucial precursors to alcohols, amines, and various functionalized molecules. A simple palladium-based system catalyzes the conversion of primary C(sp3)-H bonds in functionalized complex organic molecules into alkyl boronate esters. Amino acids, amino alcohols, alkyl amines, and a series of bioactive molecules can be functionalized with the use of readily available and removable directing groups in the presence of commercially available additives, simple ligands, and oxygen (O2) as the terminal oxidant. This approach represents an economic and environmentally friendly method that could find broad applications. Crucial additives: A simple palladium-based system catalyzes the conversion of primary C(sp3)-H bonds in complex organic molecules into alkyl boronate esters. Amino acids, amino alcohols, alkyl amines, and a series of bioactive molecules that are modified with readily available directing groups are functionalized in the presence of commercially available additives, simple ligands, and oxygen as the terminal oxidant.
Zhang, Li-Sheng,Chen, Guihua,Wang, Xin,Guo, Qing-Yun,Zhang, Xi-Sha,Pan, Fei,Chen, Kang,Shi, Zhang-Jie
supporting information
p. 3899 - 3903
(2014/05/06)

Thermal decomposition of diethylketone cyclic triperoxide in polar solvents
The thermolysis of diethylketone cyclic triperoxide (3,3,6,6,9,9-hexaethyl- 1,2,4,5,7,8-hexaoxacyclononane, DEKTP) was studied in different polar solvents (ethanol, 2-propanol, 1-butanol, 2-butanol, 2-methyl-2-propanol, and acetonitrile). The rate constant values (kd) are higher for reactions performed in secondary alcohols probably because of the possibility to form a cyclic adduct with the participation of the hydrogen atom bonded to the secondary carbon. The kinetic parameters were correlated with the physicochemical properties of the selected solvents. The products of the DEKTP thermal decomposition in different polar solvents support a radical-based decomposition mechanism. CSIRO 2014.
Barreto, Gaston P.,Alvarez, Elida E.,Eyler, Gladys N.,Canizo, Adriana I.,Allegretti, Patricia E.
p. 881 - 886
(2014/07/07)

Enantiomerically enriched tris(boronates): Readily accessible conjunctive reagents for asymmetric synthesis
The catalytic enantioselective diboration of vinyl boronate esters furnishes chiral tris(boronates) in a selective fashion. Subsequent deborylative alkylation occurs in a diastereoselective fashion, both for intermolecular and intramolecular processes.
Coombs, John R.,Zhang, Liang,Morken, James P.
supporting information
p. 16140 - 16143
(2015/01/09)

Substituent effects on oxidation-induced formation of quinone methides from arylboronic ester precursors
A series of arylboronic esters containing different aromatic substituents and various benzylic leaving groups (Br or N+Me3Br -) have been synthesized. The substituent effects on their reactivity with H2O2 and formation of quinone methide (QM) have been investigated. NMR spectroscopy and ethyl vinyl ether (EVE) trapping experiments were used to determine the reaction mechanism and QM formation, respectively. QMs were not generated during oxidative cleavage of the boronic esters but by subsequent transformation of the phenol products under physiological conditions. The oxidative deboronation is facilitated by electron-withdrawing substituents, such as aromatic F, NO2, or benzylic N+Me 3Br-, whereas electron-donating substituents or a better leaving group favor QM generation. Compounds containing an aromatic CH 3 or OMe group, or a good leaving group (Br), efficiently generate QMs under physiological conditions. Finally, a quantitative relationship between the structure and activity has been established for the arylboronic esters by using a Hammett plot. The reactivity of the arylboronic acids/esters and the inhibition or facilitation of QM formation can now be predictably adjusted. This adjustment is important as some applications may benefit and others may be limited by QM generation. Tunable quinone methide formation: Aromatic substituents and the benzylic leaving group strongly affect the H 2O2-induced formation of quinone methides (QMs) from arylboronic esters (see scheme). The reactivity of arylboronic esters can be predictably adjusted by varying substituents. Copyright
Cao, Sheng,Christiansen, Robin,Peng, Xiaohua
p. 9050 - 9058
(2013/07/26)

Synthesis of lodopyridone
The total synthesis of the unusual 4-pyridone marine metabolite lodopyridone has been achieved by late stage manipulation of the related 4-pyrone. Key reactions include a Suzuki-Miyaura coupling to form the tetracyclic core and a modified Corey-Ganem-Gilman reaction to install the ethanolamide side-chain.
George, Ian R.,Lewis, William,Moody, Christopher J.
p. 8209 - 8215
(2013/09/02)

Oxidation-responsive poly(amino ester)s containing arylboronic ester and self-immolative motif: Synthesis and degradation study
We report the synthesis of a new type of amphiphilic poly(amino ester)s which can be completely degraded in aqueous media via H2O2 oxidation. The polymers were prepared by the controlled Michael-type addition polymerization of a phenylboronic pinacol ester-containing diacrylate and N-aminoethylpiperazine, followed by postmodification with mPEG5K-succinimide ester. Upon oxidation, the side chain phenylboronic esters will be transformed into phenol groups which can trigger the sequential self-immolative process to degrade the polymer main chain. Meanwhile, the amino groups on the polymer main chain are capable of trapping the highly active quinone methides generated in situ during the oxidative degradation of the polymers. Based on the detailed oxidation kinetics and products of several model compounds, the H 2O2-triggered degradation of nanoparticles of these copolymers was investigated by NMR spectroscopy, GPC, and Nile red fluorescence probe. The results demonstrate that the poly(amino ester) backbones were completely degraded by H2O2, resulting in the dissociation of nanoparticles. Oxidative degradation rates of the nanoparticles could be accelerated by increasing the concentration of H2O2, the PEGylation degree, or the pH of the buffer. Interestingly, the in situ formed quinone methides could be captured by secondary amines due to their higher nucleophilicity than H2O. Of potential importance, these amphiphilic oxidation-responsive copolymers are sensitive to stimulation of 200 μM H 2O2; therefore, they may find application in the field of intelligent drug/gene delivery systems.
Song, Cheng-Cheng,Ji, Ran,Du, Fu-Sheng,Li, Zi-Chen
p. 8416 - 8425
(2013/12/04)

Catalytic hydrogenation of cyclic carbonates: A practical approach from CO2 and epoxides to methanol and diols
As an economical, safe and renewable carbon resource, CO2 turns out to be an attractive C1 building block for making organic chemicals, materials, and carbohydrates.[1] From the viewpoint of synthetic chemistry,[2] the utilization of CO2 as a feedstock for the production of industrial products may be an option for the recycling of carbon.[3] On the other hand, the transformation of chemically stable CO2 represents a grand challenge in exploring new concepts and opportunities for the academic and industrial development of catalytic processes.[4] The catalytic hydrogenation of CO2 to produce liquid fuels such as formic acid (HCO 2H)[5] or methanol[6] is a promising solution to emerging global energy problems. Methanol, in particular, is not only one of the most versatile and popular chemical commodities in the world, with an estimated global demand of around 48 million metric tons in 2010, but is also considered as the key to weaning the world off oil in the future.[6e, f] Although the production of methanol has already been industrialized by the hydrogenation of CO with a copper/zinc-based heterogeneous catalyst at high temperatures (250-300°C) and high pressures (50-100 atm),[6e, 7] the development of a practical catalytic system for the hydrogenation of CO2 into methanol still remains a challenge, as high activation energy barriers have to be overcome for the cleavage of the C=O bonds of CO2, albeit with favorable thermodynamics.[8] Heterogeneous catalysis for the hydrogenation of CO 2 into CH3OH has been extensively investigated, and Cu/Zn-based multi-component catalyst was found to be highly selective with a long life, but under relatively harsh reaction conditions (250 °C, 50 atm).[3b, 6d] Therefore, the production of methanol from CO2 by direct hydrogenation under mild conditions is still a great challenge for both academia and industry.
Han, Zhaobin,Rong, Liangce,Wu, Jiang,Zhang, Lei,Wang, Zheng,Ding, Kuiling
supporting information
p. 13041 - 13045
(2013/03/13)

Visible light-induced selective generation of radicals from organoborates by photoredox catalysis
A new strategy for the generation of carbon-centered radicals via oxidation of alkyl-, allyl-, benzyl- and arylborates by visible-light-driven single electron transfer (SET) photoredox catalysis has been established. The generated radicals smoothly react with TEMPO and electron-deficient alkenes to afford C-O and C-C coupling products, respectively. In this radical initiating system, cyclic organo(triol)borates turn out to be useful radical precursors.
Yasu, Yusuke,Koike, Takashi,Akita, Munetaka
supporting information
p. 3414 - 3420
(2013/02/25)

Catalytic enantioselective 1,2-diboration of 1,3-dienes: Versatile reagents for stereoselective allylation
More with boron: The development of catalytic enantioselective 1,2-diboration of 1,3-dienes enables a new strategy for enantioselective carbonyl allylation reactions (see scheme). These reactions occur with outstanding levels of stereoselection and can be applied to both monosubstituted and 1,1-disubstituted dienes. The carbonyl allylation reactions provide enantiomerically enriched functionalized homoallylic alcohol products. Copyright
Kliman, Laura T.,Mlynarski, Scott N.,Ferris, Grace E.,Morken, James P.
p. 521 - 524
(2012/03/11)

Pyrrolopyridinylpyrimidin-2-ylamine derivatives
Compounds of the formula I in which X, R1, R2, R3, R4 and R6 have the meanings indicated in Claim 1, are inhibitors of cell proliferation/cell vitality and can be employed for the treatment of tumours.
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Page/Page column 15-16

(2011/10/02)

FUSED HETEROCYCLIC COMPOUNDS AS OREXIN RECEPTOR MODULATORS
Certain disubstituted 3,8-diaza-bicyclo[4.2.0]octane and 3,6-diazabicyclo [3.2.0]heptane are described, which are useful as orexin inhibitors. Such compounds may be useful in pharmaceutical compositions and methods for the treatment of diseased states, disorders, and conditions mediated by orexin activity, such as insomnia.
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Page/Page column 77-78

(2011/05/06)

The unexpected role of pyridine-2-carboxylic acid in manganese based oxidation catalysis with pyridin-2-yl based ligands
A number of manganese-based catalysts employing ligands whose structures incorporate pyridyl groups have been reported previously to achieve both high turnover numbers and selectivity in the oxidation of alkenes and alcohols, using H2O2 as terminal oxidant. Here we report our recent finding that these ligands decompose in situ to pyridine-2-carboxylic acid and its derivatives, in the presence of a manganese source, H2O 2 and a base. Importantly, the decomposition occurs prior to the onset of catalysed oxidation of organic substrates. It is found that the pyridine-2-carboxylic acid formed, together with a manganese source, provides for the observed catalytic activity. The degradation of this series of pyridyl ligands to pyridine-2-carboxylic acid under reaction conditions is demonstrated by 1H NMR spectroscopy. In all cases the activity and selectivity of the manganese/pyridyl containing ligand systems are identical to that observed with the corresponding number of equivalents of pyridine-2-carboxylic acid; except that, when pyridine-2-carboxylic acid is used directly, a lag phase is not observed and the efficiency in terms of the number of equivalents of H 2O2 required decreases from 6-8 equiv. with the pyridin-2-yl based ligands to 1-1.5 equiv. with pyridine-2-carboxylic acid.
Pijper, Dirk,Saisaha, Pattama,De Boer, Johannes W.,Hoen, Rob,Smit, Christian,Meetsma, Auke,Hage, Ronald,Van Summeren, Ruben P.,Alsters, Paul L.,Feringa, Ben L.,Browne, Wesley R.
supporting information; experimental part
p. 10375 - 10381
(2011/01/09)

Rhenium-catalyzed deoxydehydration of glycols by sulfite
Methyltrioxorhenium and sodium perrhenate catalyze the deoxydehydration of glycols and deoxygenation of epoxides to olefins in moderate yields with sulfite as the reductant.
Vkuturi, Saidi,Chapman, Garry,Ahmad, Irshad,Nicholas, Kenneth M.
scheme or table
p. 4744 - 4746
(2010/07/09)

Activation of molecular oxygen by a dioxygenase pathway by a ruthenium bis-bipyridine compound with a proximal selenium site
A ruthenium(II) bipyridine complex with proximal phenylselenium tethers, [Ru](H2O)2, reacted intramolecularly with O2 in a protic slightly acidic solvent, 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP), to yield an O-O bond cleaved product, [Ru](O)2, with formation of two Ru-O-Se moieties. This stable compound was isolated, and its structure was determined by X-ray diffraction. The identification of the compound in solution was confirmed by ESI-MS and the 1H NMR with the associated Curie plot that showed that [Ru](O)2 was paramagnetic. The magnetic susceptibility was 2.8 μB by Evan's method suggesting a ground state triplet or biradical. DFT calculations, however, predicted a ground state singlet and an oxidized Se atom. Further it was shown that [Ru](O)2 is a potent oxygen transfer species of both O2-derived atoms to triphenylphosphine and a nucleophilic alkene such as 2,3-dimethyl-2-butene in both HFIP and acetonitrile. UV-vis spectroscopy combined with the measured stoichiometry of PPh3:O2 = 2 in a catalytic oxidation of PPh3 suggests a dioxygenase type activation of O 2 with structural identification of the O-O bond cleavage reaction step, formation of [Ru](O)2 as an intermediate, and the proof that [Ru](O)2 is a donor of both oxygen atoms.
Laskavy, Alexander,Shimon, Linda J. W.,Konstantinovski, Leonid,Iron, Mark A.,Neumann, Ronny
experimental part
p. 517 - 523
(2010/03/25)

Photo-allylation and photo-benzylation of carbonyl compounds using organotrifluoroborate reagents
Allyl- and benzyl-trifluoroborates can be applied to the photoreaction of carbonyl compounds to afford the corresponding alcoholic adducts in acceptable yields via a photo-induced single electron transfer pathway. The results were confirmed from the react
Nishigaichi, Yutaka,Orimi, Takayuki,Takuwa, Akio
experimental part
p. 3837 - 3839
(2010/03/04)

Aerobic oxidation of pinacol by vanadium(V) dipicolinate complexes: Evidence for reduction to vanadium(III)
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Hanson, Susan K.,Tom Baker, R.,Gordon, John C.,Sutton, Andrew D.,Thorn, David L.,Scott, Brian L.
supporting information; experimental part
p. 428 - 429
(2009/06/18)

OXIDATION OF ALDEHYDES AND ALKENES
A general method is disclosed for the conversion of aldehydes and alkenes to the corresponding carboxylic acids and 1,2-diols. The method is carried out in a catalyst-free aqueous medium under an atmosphere of oxygen or oxygen containing gas.
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Page/Page column 16

(2009/01/24)

Hepatitis C Virus Inhibitors
The present disclosure relates to compounds, compositions and methods for the treatment of hepatitis C virus (HCV) infection. Also disclosed are pharmaceutical compositions containing such compounds and methods for using these compounds in the treatment of HCV infection.
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Page/Page column 94

(2008/06/13)

Hepatitis C Virus Inhibitors
The present disclosure relates to compounds, compositions and methods for the treatment of hepatitis C virus (HCV) infection. Also disclosed are pharmaceutical compositions containing such compounds and methods for using these compounds in the treatment of HCV infection.
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Page/Page column 65

(2008/06/13)

A comparative study of the relative stability of representative chiral and achiral boronic esters employing transesterification
A comparative study of the transesterification of five representative chiral and achiral boronic esters with various structurally modified diols was undertaken to qualitatively understand the factors influencing the relative stability of these boronic esters. Several factors such as chelation, conformation, steric bulk of the substituents, size of the heterocycle, and entropy influence the relative rate of transesterification as well as the stability of the boronic esters. Amongst these boronic esters, pinanediol phenylboronic ester was found to be the most stable boronic ester whereas DIPT boronic ester appeared to be thermodynamically the least stable one. The transesterification with sterically hindered diols was observed to be relatively slow, but afforded thermodynamically more stable boronic esters. Boronic esters derived from cis-cyclopentanediols and the bicyclo[2.2.1]heptane-exo,exo-2,3- diols are relatively more stable. This study not only presents the qualitative picture of relative stability of various boronic esters, but also provides helpful hints regarding the possible recovery of chiral auxiliaries. Many C 2-symmetric chiral auxiliaries, such as 2,3-butanediol, 2,4-pentanediol, DIPT, and cis-cyclohexane-1,2-diol, can be retrieved by simple transesterification of the corresponding boronic esters with commercial inexpensive diols, such as pinacol, 1,3-propanediol, and neopentyl glycol.
Roy, Chandra D.,Brown, Herbert C.
p. 879 - 887
(2008/02/11)

Method for the dihydroxylation of olefins using transition metal catalysts
This invention relates to process for dihydroxylation of olefins using transition metal catalysts to obtain monofunctional, bifunctional, and/or polyfunctional 1,2-diols of the formula (I) R1R2C(OH)—C(OH)R3R4??(I) where R1to R4are defined herein, by reacting an olefin of the formula (II) R1R2C═CR3R4??(II) where R1to R4are defined as for formula (I), with molecular oxygen in the presence of an osmium, ruthenium, or manganese compound in water or a water-containing solvent mixture at a pH of from 7.5 to 13.
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Page column 8

(2008/06/13)

NOVEL PROCESS FOR PRODUCING 1,2-DIOL
A process for producing a 1,2-diol through the reaction of an olefin with hydrogen peroxide. The process is highly efficient and highly selective and catalyst recovery and reuse are easy. It does not use any strong acid or strong base causative of apparatus corrosion. The process for producing a 1,2-diol is characterized by reacting an olefin with hydrogen peroxide in the presence of a polymer having a sulfo group.
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Page 6

(2008/06/13)

Synthesis of aminoarylboronic esters and substituted anilines from arenes via catalytic C-H activation/borylation/amination and uses thereof
A process is described for synthesizing aminoarylboronic esters of the general formula wherein R, R2, and R3 are each an alkyl, aryl, vinyl, alkoxy, carboxylic esters, amides, or halogen; Ar is any variety of phenyl, naphthyl, anthracyl, heteroaryl; and R1 is alkyl, hydrogen, or aryl. The aminoarylboronic esters are produced via the metal-catalyzed coupling of arylboronic esters of the general formula wherein R and R1 are any non-interfering group and X is chloro, bromo, iodo, triflates, or nonaflates to amines (primary and secondary). In particular, a process is described for the synthesis of the aminoarylboronic esters via a step-wise or tandem process in which one catalytic event is a metal-catalyzed borylation and the other catalytic event is a metal-catalyzed amination.
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Page 7-11

(2010/02/05)