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KETONE SYNTHESIS AND APPLICATIONS
Provided are new nickel./zirconium-mediated coupling reactions useful in the synthesis of ketone-containing compounds, e.g., halichondrin natural products and related molecules. A feature of the present disclosure is the use of a nickel(I) catalyst in tandem with a nickel (II) catalyst in the Ni/Zr-mediated coupling reactions. Without wishing to be bound by any particular theory, the nickel (I) catalyst selectively activates the electrophilic coupling partner (i.e., the compound of Formula (A)), and the nickel(ll) catalyst selectively activates the nucleophilic coupling partner (i.e., a thioester of Formula (B)). This dual catalyst system leads to improved coupling efficiency and eliminates the need for a large excess of one of the coupling partners (i.e., a compound of Formula (A) or (B)).
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Paragraph 00238; 00252

(2022/02/05)

Palladium-Catalyzed Selective Reduction of Carbonyl Compounds
Two new examples of structurally characterized β-diketiminate analogues i.e., conjugated bis-guanidinate (CBG) supported palladium(II) complexes, [LPdX]2; [L= {(ArHN)(ArN)–C=N–C=(NAr)(NHAr)}; Ar = 2,6-Et2-C6H3], X = Cl (1), Br (2) have been reported. The synthesis of complexes 1–2 was achieved by two methods. Method A involves deprotonation of LH by nBuLi followed by the treatment of LLi (insitu formed) with PdCl2 in THF, which afforded compound 1 in good yield (75 %). In Method B, the reaction between free LH and PdX2 (X = Cl or Br) in THF allowed the formation of complexes 1 (Yield 73 %) and 2 (Yield 52 %), respectively. Moreover, these complexes were characterized thoroughly by several spectroscopic techniques (1H, 13C NMR, UV/Vis, FT-IR, and HRMS), including single-crystal X-ray structural and elemental analyses. In addition, we tested the catalytic activity of these complexes 1–2 for the hydroboration of carbonyl compounds with pinacolborane (HBpin). We observed that compound 1 exhibits superior catalytic activity when compared to 2. Compound 1 efficiently catalyzes various aldehydes and ketones under solvent-free conditions. Furthermore, both inter- and intramolecular chemoselectivity hydroboration of aldehydes over other functionalities have been established.
Sarkar, Nabin,Mahato, Mamata,Nembenna, Sharanappa
p. 2295 - 2301
(2020/05/18)

Nickel-Catalyzed Formal Aminocarbonylation of Unactivated Alkyl Iodides with Isocyanides
Herein, we disclose a Ni-catalyzed formal aminocarbonylation of primary and secondary unactivated aliphatic iodides with isocyanides to afford alkyl amide, which proceeds via the selective monomigratory insertion of isocyanides with alkyl iodides, subsequent β-hydride elimination, and hydrolysis process. The reaction features wide functional group tolerance under mild conditions. Additionally, the selective, one-pot hydrolysis of reaction mixture under acid conditions allows for expedient synthesis of the corresponding alkyl carboxylic acid.
Chen, Yifeng,Huang, Wenyi,Qu, Jingping,Shrestha, Mohini,Wang, Yun,Weng, Yangyang
supporting information
p. 3245 - 3250
(2020/04/21)

Erbium-Catalyzed Regioselective Isomerization-Cobalt-Catalyzed Transfer Hydrogenation Sequence for the Synthesis of Anti-Markovnikov Alcohols from Epoxides under Mild Conditions
Herein, we report an efficient isomerization-transfer hydrogenation reaction sequence based on a cobalt pincer catalyst (1 mol %), which allows the synthesis of a series of anti-Markovnikov alcohols from terminal and internal epoxides under mild reaction conditions (≤55 °C, 8 h) at low catalyst loading. The reaction proceeds by Lewis acid (3 mol % Er(OTf)3)-catalyzed epoxide isomerization and subsequent cobalt-catalyzed transfer hydrogenation using ammonia borane as the hydrogen source. The general applicability of this methodology is highlighted by the synthesis of 43 alcohols from epoxides. A variety of terminal (23 examples) and 1,2-disubstituted internal epoxides (14 examples) bearing different functional groups are converted to the desired anti-Markovnikov alcohols in excellent selectivity and yields of up to 98%. For selected examples, it is shown that the reaction can be performed on a preparative scale up to 50 mmol. Notably, the isomerization step proceeds via the most stable carbocation. Thus, the regiochemistry is controlled by stereoelectronic effects. As a result, in some cases, rearrangement of the carbon framework is observed when tri-and tetra-substituted epoxides (6 examples) are converted. A variety of functional groups are tolerated under the reaction conditions even though aldehydes and ketones are also reduced to the respective alcohols under the reaction conditions. Mechanistic studies and control experiments were used to investigate the role of the Lewis acid in the reaction. Besides acting as the catalyst for the epoxide isomerization, the Lewis acid was found to facilitate the dehydrogenation of the hydrogen donor, which enhances the rate of the transfer hydrogenation step. These experiments additionally indicate the direct transfer of hydrogen from the amine borane in the reduction step.
Liu, Xin,Longwitz, Lars,Spiegelberg, Brian,T?njes, Jan,Beweries, Torsten,Werner, Thomas
p. 13659 - 13667
(2020/11/30)

Cerium(IV) Carboxylate Photocatalyst for Catalytic Radical Formation from Carboxylic Acids: Decarboxylative Oxygenation of Aliphatic Carboxylic Acids and Lactonization of Aromatic Carboxylic Acids
We found that in situ generated cerium(IV) carboxylate generated by mixing the precursor Ce(OtBu)4 with the corresponding carboxylic acids served as efficient photocatalysts for the direct formation of carboxyl radicals from carboxylic acids under blue light-emitting diodes (blue LEDs) irradiation and air, resulting in catalytic decarboxylative oxygenation of aliphatic carboxylic acids to give C-O bond-forming products such as aldehydes and ketones. Control experiments revealed that hexanuclear Ce(IV) carboxylate clusters initially formed in the reaction mixture and the ligand-to-metal charge transfer nature of the Ce(IV) carboxylate clusters was responsible for the high catalytic performance to transform the carboxylate ligands to the carboxyl radical. In addition, the Ce(IV) carboxylate cluster catalyzed direct lactonization of 2-isopropylbenzoic acid to produce the corresponding peroxy lactone and ?3-lactone via intramolecular 1,5-hydrogen atom transfer (1,5-HAT).
Hirosawa, Keishi,Mashima, Kazushi,Satoh, Tetsuya,Shinohara, Koichi,Shirase, Satoru,Tamaki, Sota,Tsurugi, Hayato
supporting information

(2020/03/25)

Base-Free Iron Catalyzed Transfer Hydrogenation of Esters Using EtOH as Hydrogen Source
Herein, we report on the use of the iron pincer complex Iron-MACHO-BH, in the base-free transfer hydrogenation of esters with EtOH as a hydrogen source. More than 20 substrates including aromatic and aliphatic esters and lactones were reduced affording the desired primary alcohols and diols with moderate to excellent isolated yields. It is also possible to reduce polyesters to the diols with this method, enabling a novel way of plastic recycling. Reduction of the renewable substrate methyl levulinate proceeds to form 1,4-pentanediol directly. The yields are largely governed by the equilibrium between the alcohol and the ethyl ester.
Farrar-Tobar, Ronald A.,Wozniak, Bartosz,Savini, Arianna,Hinze, Sandra,Tin, Sergey,de Vries, Johannes G.
supporting information
p. 1129 - 1133
(2019/01/04)

Pd/meso-CoO derived from: In situ reduction of the one-step synthesized Pd/meso-Co3O4: High-performance catalysts for benzene combustion
The chemical state of Pd plays an important role in the catalytic combustion of volatile organic compounds (VOCs). In this work, we adopted a novel one-step modified KIT-6-templating strategy with nitrates of cobalt and palladium as the metal source to successfully synthesize the three-dimensionally ordered mesoporous Co3O4-supported Pd nanoparticles (0.85 wt% Pd/meso-Co3O4, denoted as 0.85Pd/meso-Co3O4). The 0.93 wt% Pd/meso-CoO (denoted as 0.93Pd/meso-CoO) and 1.08 wt% Pd/meso-Co-CoO (denoted as 1.08Pd/meso-Co-CoO) samples were prepared via in situ reduction of 0.85Pd/meso-Co3O4 in a H2 flow at 200 and 350 °C, respectively. Among these samples, 0.93Pd/meso-CoO exhibited the highest catalytic activity for benzene combustion (T50% = 167 °C and T90% = 189 °C at a space velocity of 40000 mL (g h)-1). The chemical state of Pd on the 0.93Pd/meso-CoO surface was metallic Pd0, which favored oxygen activation to active adsorbed oxygen (Oads) species, hence rendering this sample to possess the largest desorption of Oads species below 400 °C. The intermediates of formate, acetate, maleate, and phenolate were generated via the interaction of benzene and Oads species. We conclude that the excellent catalytic performance of 0.93Pd/meso-CoO was related to the mainly formed Pd0 species, good oxygen activation ability, and high surface area.
Zhao, Xingtian,Zhang, Ran,Liu, Yuxi,Deng, Jiguang,Xu, Peng,Lv, Sijie,Li, Shuang,Pei, Wenbo,Zhang, Kunfeng,Dai, Hongxing
supporting information
p. 12358 - 12368
(2019/08/12)

Rhenium-catalyzed deoxydehydration of renewable triols derived from sugars
An efficient method for the catalytic deoxydehydration of renewable triols, including those obtained from 5-HMF, is described. The corresponding unsaturated alcohols were obtained in good yields using simple rhenium(vii)oxide under neat conditions and ambient atmosphere at 165 °C.
Wozniak, Bartosz,Li, Yuehui,Tin, Sergey,De Vries, Johannes G.
supporting information
p. 4433 - 4437
(2018/10/17)

Visible-Light-Mediated Aerobic Oxidation of Organoboron Compounds Using in Situ Generated Hydrogen Peroxide
A simple and general visible-light-mediated oxidation of organoboron compounds has been developed with rose bengal as the photocatalyst, substoichiometric Et3N as the electron donor, as well as air as the oxidant. This mild and metal-free protocol shows a broad substrate scope and provides a wide range of aliphatic alcohols and phenols in moderate to excellent yields. Notably, the robustness of this method is demonstrated on the stereospecific aerobic oxidation of organoboron compounds.
Weng, Wei-Zhi,Liang, Hao,Zhang, Bo
supporting information
p. 4979 - 4983
(2018/08/24)

Selective Hydrogenations and Dechlorinations in Water Mediated by Anionic Surfactant-Stabilized Pd Nanoparticles
We report a facile, inexpensive, and green method for the preparation of Pd nanoparticles in aqueous medium stabilized by anionic sulfonated surfactants sodium 1-dodecanesulfonate 1a, sodium dodecylbenzenesulfonate 1b, dioctyl sulfosuccinate sodium salt 1c, and poly(ethylene glycol) 4-nonylphenyl-3-sulfopropyl ether potassium salt 1d simply obtained by stirring aqueous solutions of Pd(OAc)2 with the commercial anionic surfactants further treated under hydrogen atmosphere for variable amounts of time. The aqueous Pd nanoparticle solutions were tested in the selective hydrogenation reactions of aryl-alcohols, -aldehydes, and -ketones, leading to complete conversion to the deoxygenated products even in the absence of strong Br?nsted acids in the reduction of aromatic aldehydes and ketones, in the controlled semihydrogenation of alkynes leading to alkenes, and in the efficient hydrodechlorination of aromatic substrates. In all cases, the micellar media were crucial for stabilizing the metal nanoparticles, dissolving substrates, steering product selectivity, and enabling recycling. What is interesting is also that a benchmark catalyst like Pd/C can often be surpassed in activity and/or selectivity in the reactions tested by simply switching to the appropriate commercially available surfactant, thereby providing an easy to use, flexible, and practical catalytic system capable of efficiently addressing a variety of synthetically significant hydrogenation reactions.
La Sorella, Giorgio,Sperni, Laura,Canton, Patrizia,Coletti, Lisa,Fabris, Fabrizio,Strukul, Giorgio,Scarso, Alessandro
supporting information
p. 7438 - 7446
(2018/05/29)

Additive-modulated switchable reaction pathway in the addition of alkynes with organosilanes catalyzed by supported Pd nanoparticles: Hydrosilylation: versus semihydrogenation
We herein report supported Pd nanoparticles on N,O-doped hierarchical porous carbon as a single operation catalyst-enabled additive-modulated reaction pathway for alkynes addition with organosilanes between hydrosilyation and semihydrogenation. In the case of alkynes hydrosilylation, a simple iodide ion as an additive has a promotion effect on the activity and regio- and stereoselectivity, where iodide can coordinate with Pd NPs via strong δ donation to increase the electron density of the Pd atom, resulting in an increased ability for the oxidative addition of hydrosilane as the rate-determining step to make the reaction proceed efficiently to afford vinylsilanes in high yields with excellent regio- and stereoselectivity. For the catalytic transfer semihydrogenation of alkynes, water was introduced to mix with organosilane to form a silanol together with the generation of hydrogen atoms on the Pd NPs surface or the liberation of H2 gas as a reducing agent, whereby the quantitative reduction of alkynes was achieved with exclusive selectivity to alkenes. In both cases, the catalyst could be recycled several times without a significant loss in activity or selectivity. A broad range of alkyl and aryl alkynes with various functional groups are compatible with the reaction conditions. The role the additive exerted in each reaction was extensively investigated through control experiments as well as the kinetic isotopic effect along with spectroscopic characterization. In addition, the respective mechanism operating in both reactions was proposed.
Duan, Yanan,Ji, Guijie,Zhang, Shaochun,Chen, Xiufang,Yang, Yong
p. 1039 - 1050
(2018/03/05)

Palladium-Catalyzed Electrochemical Allylic Alkylation between Alkyl and Allylic Halides in Aqueous Solution
A new route for the direct cross-coupling of alkyl and allylic halides using electrochemical technique has been developed in aqueous media under air. Catalyzed by Pd(OAc)2, the Zn-mediated allylic alkylations proceed smoothly between a full range of alkyl halides (primary, secondary, and tertiary) and substituted allylic halides. Protection-deprotection of acidic hydrogen in the substrates is avoided.
Lai, Yin-Long,Huang, Jing-Mei
supporting information
p. 2022 - 2025
(2017/04/28)

Selective Semihydrogenation of Alkynes Catalyzed by Pd Nanoparticles Immobilized on Heteroatom-Doped Hierarchical Porous Carbon Derived from Bamboo Shoots
Highly dispersed palladium nanoparticles (Pd NPs) immobilized on heteroatom-doped hierarchical porous carbon supports (N,O-carbon) with large specific surface areas are synthesized by a wet chemical reduction method. The N,O-carbon derived from naturally abundant bamboo shoots is fabricated by a tandem hydrothermal–carbonization process without assistance of any templates, chemical activation reagents, or exogenous N or O sources in a simple and ecofriendly manner. The prepared Pd/N,O-carbon catalyst shows extremely high activity and excellent chemoselectivity for semihydrogenation of a broad range of alkynes to versatile and valuable alkenes under ambient conditions. The catalyst can be readily recovered for successive reuse with negligible loss in activity and selectivity, and is also applicable for practical gram-scale reactions.
Ji, Guijie,Duan, Yanan,Zhang, Shaochun,Fei, Benhua,Chen, Xiufang,Yang, Yong
p. 3427 - 3434
(2017/09/15)

ReOx/TiO2: A Recyclable Solid Catalyst for Deoxydehydration
Deoxydehydration (DODH) enables the transformation of two adjacent hydroxyl functions into a C-C double bond: e.g., facilitating synthesis of 1,3,5-hexatriene from sorbitol. Here we report the first stable heterogeneous catalyst for DODH based on ReOx supported on TiO2. ReOx/TiO2 exhibits not only catalytic activity and selectivity comparable to those of previously described molecular rhenium catalysts but also excellent stability without deactivation over at least six consecutive runs. X-ray absorption spectroscopy (XAFS) measurements indicate a mixture of Re(VII), Re(IV), and Re(0) species at a ratio of 0.47:0.27:0.25, remaining comparatively stable during catalysis.
Sandbrink, Lennart,Klindtworth, Elisabeth,Islam, Husn-Ubayda,Beale, Andrew M.,Palkovits, Regina
p. 677 - 680
(2016/02/18)

Fabrication of Ultrafine Palladium Phosphide Nanoparticles as Highly Active Catalyst for Chemoselective Hydrogenation of Alkynes
Monodisperse palladium phosphide nanoparticles (Pd-P NPs) with a smallest size ever reported of 3.9nm were fabricated using cheap and stable triphenylphosphine as phosphorous source. After the deposition and calcination at 300 °C and 400 °C, the resulting Pd-P NPs increased in size to 4.0nm and 4.8nm, respectively. Notably, the latter NPs probably crystallized with a single phase of Pd3P0.95, which acted as a highly active catalyst in semi-and stereoselective hydrogenation of alkynes. X-ray photoelectron spectroscopy analysis determined a positive shift of binding energy for Pd(3d) in Pd-P NPs compared to that in Pd on carbon. It indicated the electron flow from metal to phosphorus and the larger electron deficiency of Pd in Pd-P NPs, which suppressed palladium hydride formation and subsequently increased the selectivity. Thus, this result may also indicate the applications of Pd-P and other metal-P NPs in various selective hydrogenation reactions.
Zhao, Ming
p. 461 - 464
(2016/03/12)

Direct reduction of 1,2- and 1,6-dibromohexane at silver cathodes in dimethylformamide
Electrochemical reduction of 1,2-dibromohexane (1) and 1,6-dibromohexane (2) at silver cathodes in dimethylformamide (DMF) containing tetramethylammonium perchlorate (TMAP) has been investigated with the aid of cyclic voltammetry and controlled-potential electrolysis. Cyclic voltammograms for reduction of 1 and 2 both exhibit a single irreversible cathodic peak associated with reduction of carbon-bromine bonds; however, the cathodic peak potential (-0.33 V) for 1 is significantly less negative than that (-1.00 V) for 2, and the peak current for 1 is approximately half of that for 2. Cyclic voltammograms for 0.5-20.0 mM solutions of 1 and 2, separately, show that the parameter Ipc/C?increases as the concentration (C?) decreases; this trend is likely due to a combination of adsorption phenomena and a potential-dependent transfer coefficient (α). Coulometric n values and product distributions arising from bulk electrolyses of 5.0 mM solutions of 1 and 2 depend on the positions of the bromine atoms: (a) for 1, n was 2.13 and 1-hexene was the only product; (b) for 2, n was 2.12 and a mixture of products was obtained [1-hexene (21%), n-hexane (37%), 1,5-hexadiene (22%), 5-hexen-1-ol (9%), and a trace of n-dodecane]. When 2 was electrolyzed in the presence of a proton or deuteron donor (2,2,2-trifluoroethanol or D2O), the n value and the amount of n-hexane increased, whereas 1-hexene and 1,5-hexadiene decreased in yield. We conclude that reduction of 1 follows a concerted mechanism, but that reduction of 2 proceeds via carbanionic intermediates.
Martin, Erin T.,Strawsine, Lauren M.,Mubarak, Mohammad S.,Peters, Dennis G.
p. 369 - 376
(2015/11/17)

On the Functional Group Tolerance of Ester Hydrogenation and Polyester Depolymerisation Catalysed by Ruthenium Complexes of Tridentate Aminophosphine Ligands
The synthesis of a range of phosphine-diamine, phosphine-amino-alcohol, and phosphine-amino-amide ligands and their ruthenium(II) complexes are reported. Five of these were characterised by X-ray crystallography. The activities of this collection of catalysts were initially compared for the hydrogenation of two model ester hydrogenations. Catalyst turnover frequencies up to 2400 h-1 were observed at 85 °C. However, turnover is slow at near ambient temperatures. By using a phosphine-diamine RuII complex, identified as the most active catalyst, a range of aromatic esters were reduced in high yield. The hydrogenation of alkene-, diene-, and alkyne-functionalised esters was also studied. Substrates with a remote, but reactive terminal alkene substituent could be reduced chemoselectively in the presence of 4-dimethylaminopyridine (DMAP) co-catalyst. The chemoselective reduction of the ester function in conjugated dienoate ethyl sorbate could deliver (2E,4E)-hexa-2,4-dien-1-ol, a precursor to leaf alcohol. The monounsaturated alcohol (E)-hex-4-en-1-ol was produced with reasonable selectivity, but complete chemoselectivity of C=O over the diene is elusive. High chemoselectivity for the reduction of an ester over an alkyne group was observed in the hydrogenation of an alkynoate for the first time. The catalysts were also active in the depolymerisation reduction of samples of waste poly(ethylene terephthalate) (PET) to produce benzene dimethanol. These depolymerisations were found to be poisoned by the ethylene glycol side product, although good yields could still be achieved. A simple catalyst for difficult reductions: Ruthenium complexes of P,N,N and P,N,O ligands catalyse the reduction of esters with high activities. The Ru complex of a phosphine-diamine ligand (see scheme) has been found to be a good catalyst for reducing alkene-, diene-, and alkyne-functionalised esters, displaying good activity and chemoselectivity. This catalyst was also active in the hydrogenation of waste poly(ethylene terephthalate) (PET).
Fuentes, José A.,Smith, Samuel M.,Scharbert, M. Theresa,Carpenter, Ian,Cordes, David B.,Slawin, Alexandra M. Z.,Clarke, Matthew L.
supporting information
p. 10851 - 10869
(2015/07/20)

cis-Semihydrogenation of alkynes with amine borane complexes catalyzed by gold nanoparticles under mild conditions
Supported gold nanoparticles catalyze the semihydrogenation of alkynes to alkenes with ammonia borane or amine borane complexes in excellent yields and under mild conditions. Internal alkynes provide cis-alkenes, making this protocol an attractive alternative of the classical Lindlar's hydrogenation.
Vasilikogiannaki, Eleni,Titilas, Ioannis,Vassilikogiannakis, Georgios,Stratakis, Manolis
supporting information
p. 2384 - 2387
(2015/02/05)

Syntheses of aldol products and cyanohydrins from carboxylic acids using hydrosilanes, organosilicon reagents, and indium triiodide catalyst
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Inamoto, Yoshihiro,Nishimoto, Yoshihiro,Yasuda, Makoto,Baba, Akio
p. 1551 - 1553
(2014/01/06)

Core-shell AgNP@CeO2 nanocomposite catalyst for highly chemoselective reductions of unsaturated aldehydes
Selective silver: A core-shell AgNP-CeO2 nanocomposite (AgNP@CeO2) acted as an effective catalyst for the chemoselective reductions of unsaturated aldehydes to unsaturated alcohols with H2 (see figure). Maximizing the AgNP-CeO2 interaction successfully induced the heterolytic cleavage of H2, resulting in highly chemoselective reductions. Furthermore, a highly dispersed AgNP@CeO2 system was also developed that exhibited a higher activity than the original AgNP@CeO2. Copyright
Mitsudome, Takato,Matoba, Motoshi,Mizugaki, Tomoo,Jitsukawa, Koichiro,Kaneda, Kiyotomi
supporting information
p. 5255 - 5258
(2013/05/22)

Remarkable effect of bases on core-shell AgNP@CeO2 nanocomposite-catalyzed highly chemoselective reduction of unsaturated aldehydes
A highly dispersed coreshell silver nanoparticleceria nanocomposite catalyst (AgNP@CeO2-D) was prepared. The addition of bases was found to enhance the catalytic efficiency of AgNP@CeO2-D significantly in the chemoselective reduction of diverse unsaturated aldehydes to the corresponding unsaturated alcohols.
Mitsudome, Takato,Matoba, Motoshi,Yamamoto, Masaaki,Mizugaki, Tomoo,Jitsukawa, Koichiro,Kaneda, Kiyotomi
p. 660 - 662
(2013/07/05)

Z -selective ethenolysis with a ruthenium metathesis catalyst: Experiment and theory
The Z-selective ethenolysis activity of chelated ruthenium metathesis catalysts was investigated with experiment and theory. A five-membered chelated catalyst that was successfully employed in Z-selective cross metathesis reactions has now been found to be highly active for Z-selective ethenolysis at low ethylene pressures, while tolerating a wide variety of functional groups. This phenomenon also affects its activity in cross metathesis reactions and prohibits crossover reactions of internal olefins via trisubstituted ruthenacyclobutane intermediates. In contrast, a related catalyst containing a six-membered chelated architecture is not active for ethenolysis and seems to react through different pathways more reminiscent of previous generations of ruthenium catalysts. Computational investigations of the effects of substitution on relevant transition states and ruthenacyclobutane intermediates revealed that the differences of activities are attributed to the steric repulsions of the anionic ligand with the chelating groups.
Miyazaki, Hiroshi,Herbert, Myles B.,Liu, Peng,Dong, Xiaofei,Xu, Xiufang,Keitz, Benjamin K.,Ung, Thay,Mkrtumyan, Garik,Houk,Grubbs, Robert H.
supporting information
p. 5848 - 5858
(2013/05/22)

A biocatalytic hydrogenation of carboxylic acids
The hyperthermophile Pyrococcus furiosus catalyses the hydrogenation of a broad range of carboxylic acids selectively to the corresponding primary alcohols. Other functional groups such as isolated CC-double bonds are not touched. The chemoselectivity of the carboxylate reduction may be directed towards aldehydes by simple medium engineering.
Ni, Yan,Hagedoorn, Peter-Leon,Xu, Jian-He,Arends, Isabel W. C. E.,Hollmann, Frank
supporting information
p. 12056 - 12058
(2013/01/16)

Iron-catalysed cross-coupling of halohydrins with aryl aluminium reagents: A protecting-group-free strategy attaining remarkable rate enhancement and diastereoinduction
Non-protected halohydrins are cross-coupled with aryl aluminium reagents to produce aryl alkanols in the presence of the iron-bisphosphine catalysts. Remarkable reaction rate enhancement and diastereoinduction are realized by the in situ generated aluminium alkoxides, offering a new method for the reactivity and selectivity control of the iron-catalysed cross-coupling reaction.
Kawamura, Shintaro,Kawabata, Tatsuya,Ishizuka, Kentaro,Nakamura, Masaharu
supporting information; experimental part
p. 9376 - 9378
(2012/09/22)

Vapor-phase catalytic dehydration of terminal diols
Vapor-phase catalytic reactions of several terminal diols were investigated over several rare earth oxides, such as Sc2O3, Y 2O3, CeO2, Yb2O3, and Lu2O3. Sc2O3 showed selective catalytic activity in the dehydration of terminal diols with long carbon chain, such as 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, and 1,12-dodecanediol, to produce the corresponding unsaturated alcohols. In the dehydration of 1,6-hexanediol, 5-hexen-1-ol was produced with selectivity over 60 mol%, together with by-products such as ε-caprolactone and oxacycloheptane. In the dehydration of 1,10-decanediol, 9-decen-1-ol was produced with selectivity higher than 70 mol%. In addition to Sc 2O3, heavy rare earth oxides such as Lu2O 3 as well as monoclinic ZrO2 showed moderate selectivity in the dehydration of the terminal diols.
Abe, Katsutoshi,Ohishi, Yusuke,Okada, Takuto,Yamada, Yasuhiro,Sato, Satoshi
experimental part
p. 419 - 424
(2012/02/03)

M -Terphenyl Ethers, a new hydroxy protecting group cleavable under reductive single electron transfer reaction conditions
m-Terphenyl ethers and, to a lesser extent, 2,6-dimethoxyphenyl ethers, were tested as protected hydroxy derivatives under a variety of reaction conditions. These ethers underwent regioselective cleavage of the aromatic C(1)-O bond under reductive SET reaction conditions using alkali metals in tetrahydrofuran at room temperature. This deprotective procedure was efficiently realized in the presence of several other functional groups, including an acetal, a phenyl alkyl ether, an unprotected alcohol, and carbon-carbon double and triple bonds. Furthermore, m-terphenyl ethers proved stable under different reaction conditions, including acidic hydrolysis and formation and/or employment of different organometallic reagents. Georg Thieme Verlag Stuttgart · New York.
Azzena, Ugo,Mocci, Sarah,Pisano, Luisa
p. 1575 - 1580
(2011/06/24)

Chemoselective oxygen-centered radical cyclizations onto silyl enol ethers
(Chemical Equation Presented) A new oxygen-centered radical cyclization onto silyl enol ethers has been developed and utilized for the synthesis of versatile siloxy-substituted tetrahydrofurans. The reactions display excellent chemoselectivity for cyclization onto the electron-rich silyl enol ether when competing terminal alkene cyclization, 1,5-hydrogen abstraction, and β-fragmentation pathways are present. The increased chemoselectivity also allows for the synthesis of tetrahydropyrans, a challenging substrate class to access using oxygen-centered radical alkene cyclizations due to competing 1, 5-hydrogen abstractions.
Zlotorzynska, Maria,Zhai, Huimin,Sammis, Glenn M.
supporting information; experimental part
p. 5083 - 5086
(2009/05/31)

Facile photochemical transformation of alkyl aryl selenides to the corresponding carbonyl compounds by molecular oxygen: Use of selenides as masked carbonyl groups
(Chemical Equation Presented) Alkyl aryl selenides with and without functional groups on the alkyl group were transformed efficiently into the corresponding carbonyl compounds, particulary primary alkyl aryl selenides in good yields, by a simple photolysis in the presence of air or oxygen. This transformation can be conducted without protection of functional groups. The yield of carbonyl compounds was much affected by the solvent viscosity, reaction temperature, concentration of dissolved oxygen in the solvents, wavelength of light, and structure of the aryl substituents. The present study indicates that aryl selenides can be considered as a masked carbonyl group that can be easily converted to a carbonyl group by very mild reaction conditions even in the presence of various unprotected functional groups. Therefore, this functional group transformation can be used as an important tool in organic synthesis due to its simplicity and mild reaction condition.
Hyugano, Takeshi,Liu, Suyou,Ouchi, Akihiko
supporting information; scheme or table
p. 8861 - 8866
(2009/04/05)

Application of the intramolecular isomerisation - Aldolisation from allylic alcohols and allylic silyl ethers to the synthesis of indanones and indenones
A new access to indanones was discovered through a one-step nickel or iron-mediated transposition of 2-hydroxyisobenzofurans. Starting from the corresponding silylenol ethers, a new one-pot tandem isomerisation-Mukaiyama aldol process was also developed. These versatile strategies will be useful for the preparation of various types of indanones and indenones.
Petrignet, Julien,Roisnel, Thierry,Gree, Rene
p. 7374 - 7384
(2008/03/14)

Alkyl radical generation in water under ambient conditions - A new look at the Guareschi reaction of 1897
(Chemical Equation Presented) Chemical and biochemical significance of a long-forgotten 19th century observation: The hydrocarbon production from quaternary glutarimides on neutralization in water is the consequence of formation of alkyl radicals, which means that it is possible to generate alkyl radicals under very mild conditions. Oxygen trapping competes with hydrogen abstraction (see scheme).
Nguyen, Bao,Chernous, Katya,Endlar, Daniel,Odell, Barbara,Piacenti, Michela,Brown, John M.,Dorofeev, Alexander S.,Burasov, Alexander V.
p. 7655 - 7658
(2008/09/18)

Synthesis of beta-L-2'-deoxy nucleosides
An improved process for the preparation of 2′-modified nucleosides and 2′-deoxy-nucleosides, such as, β-L-2′-deoxy-thymidine (LdT), is provided. In particular, the improved process is directed to the synthesis of a 2′-deoxynucleoside that may utilize different starting materials but that proceeds via a chloro-sugar intermediate or via a 2,2′-anhydro-1-furanosyl-nucleobase intermediate. Where an 2,2′-anhydro-1-furanosyl base intermediate is utilized, a reducing agent, such as Red-Al, and a sequestering agent, such as 15-crown-5 ether, that cause an intramolecular displacement reaction and formation of the desired nucleoside product in good yields are employed. An alternative process of the present invention utilizes a 2,2′-anhydro-1-furanosyl base intermediate without a sequestering agent to afford 2′-deoxynucleosides in good yields. The compounds made according to the present invention may be used as intermediates in the preparation of other nucleoside analogues, or may be used directly as antiviral and/or antineoplastic agents.
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Page/Page column 28; 29

(2010/02/11)

Ultrasound-accelerated synthesis of chiral allylic alcohols promoted by indium metal
The 2-iodomethyl-O-isopropylidine acetals undergo smoothly β-elimination by indium metal in methanol under sonication to afford the corresponding allylic alcohols in excellent yields with high selectivity. This method tolerates both acid and base labile functional and protecting groups and also free hydroxyl groups present in the molecule. Improved yields and enhanced rates are the remarkable features obtained by ultrasound.
Yadav,Reddy,Srinivasa Reddy
p. 5333 - 5336
(2007/10/03)

Microwave catalyzed reactions of H-dimethylphosphonate with oxiranes
Microwave catalyzed reactions of H-dimethylphosphonate with 1,2-epoxydecane, 5,6-epoxy-1-hexene, 1,2-epoxybutane and cyclohexene oxide have been found to cause oxirane ring opening, deoxygenation and hydrophosphorylation. 1,2-Epoxydecane gave three pairs
Munavalli,Rohrbaugh,Berg,Longo,Durst
p. 215 - 230
(2007/10/03)

Synthesis of C3-C9-alkenyl 2,3-unsaturated glucosides from glucose and some alkenols
C3-C9-Alkenyl 2,3-unsaturated glucosides have been synthesized from glucose and C3-C9-alkenols by using Ferrier reaction with boron trifluoride etherate (BF3·Et2O) as Lewis acid catalyst in key step.
Konstantinovic,Predojevic,Gojkovic,Ratkovic,Dimitrijevic,Mojsilovic
p. 802 - 805
(2007/10/03)

Intramolecular Diels-Alder reactions of 4H-furo[3,4-b]indoles. New syntheses of benzo[a]carbazoles and benzo[c]carbazoles
Furoindoles 7 and 16 undergo smooth intramolecular Diels-Alder reactions to afford, after dehydration, hydrolysis, and oxidation, benzocarbazoles 11 and 21, respectively.
Gribble, Gordon W.,Silva, Richard A.,Saulnier, Mark G.
p. 729 - 747
(2007/10/03)

Synthese d'acides ω perfluoroalkylalcanoiques et d'ω perfluoroalkylalcanols
The simple and effective syntheses of acids and alcohols of general formula CnF2n+1(CH2)mY (Y=CO2H, CH2OH; n=6,8 and m=4,5) have been described.
Tra Anh,Blancou,Commeyras
p. 167 - 174
(2007/10/03)

Facile Synthesis of Spirocyclic Systems through the Intramolecular Addition of Ketyl Radicals via the Sodium/Ammonia Reduction of δ,ε-Unsaturated Carboxylic Esters
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Cossy, Janine,Gille, Barbara,Bellosta, Veronique
p. 3141 - 3146
(2007/10/03)

Tetrahydrofuran, tetrahydropyran and oxepane formation by cobaloxime π-cation cyclizations
Studies are reported on the cyclization of (ω-hydroxy-β-hydroxyalkyl)cobaloximes (1, 2 and 3) to form 5,6 and 7-membered ring cyclic ethers (4, 5 and 6). Reversible cyclization and eventual irreversible alkene decomplexation (to form 7, 8 and 9) varied as a function of ring size. The practical consequence is that cyclizations to form 5 and 6 membered rings are feasible whereas formation of a 7 membered ring is not.
Grubb, Lana M.,Brown, Katherine A.,Branchaud, Bruce P.
p. 3447 - 3448
(2007/10/03)

Microwave thermolysis IV: Selective deprotection of MPM ethers using clay supported ammonium nitrate 'clayan' in dry media
Selective deprotection of (4-methoxyphenyl)-methyl (MPM) ethers using clay supported ammonium nitrate under microwave irradiation is described. The use of expensive reagents and problems associated with slurry reactions are avoided.
Yadav,Meshram,Sudershan Reddy,Sumithra
p. 3043 - 3046
(2007/10/03)

Selective and unprecedented oxidative deprotection of allyl ethers with DDQ
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Yadav,Chandrasekhar,Sumithra,Kache, Rajashaker
p. 6603 - 6606
(2007/10/03)

Rapid dehydrosulfenylation of sulfoxides under microwave irradiation
Pyrolytic β-elimination of sulfoxides has been promoted by microwave irradiation. The reaction is very fast and yields are almost quantitative.
Matloubi Moghaddam, Firouz,Ghaffarzadeh, Mohammad
p. 1855 - 1858
(2007/10/03)

Electrochemical Reduction of 1,6-Dihalohexanes at Carbon Cathodes in Dimethylformamide
Cyclic voltammograms for the reduction of 1,6-dibromo-, 1,6-diiodo-, 1-bromo-6-chloro-, and 1-chloro-6-iodohexane at glassy carbon electrodes in dimethylformamide containing tetramethylammonium perchlorate exhibit single irreversible waves that correspond to the reductive cleavage of carbon-bromine or carbon-iodine bonds.When large-scale controlled-potential electrolyses of either 1,6-dibromo- or 1,6-diiodohexane are performed at reticulated vitreous carbon, the principal products are n-hexane (30-45percent), 1-hexene (28-34percent), 1,5-hexadiene (6-16percent), and cyclohexane (7percent), with n-dodecane being another significant species obtained from 1,6-diiodohexane.Because a carbon-chlorine bond is not directly reducible, 1-bromo-6-chloro- and 1-chloro-5-iodohexane give rise mainly to 1-chlorohexane (47-64percent), 6-chloro-1-hexene (20-33percent), and 1,12-dichlorododecane (2-25percent).From these product distributions, and with the aid of experiments done in the presence of deuterium-labeled reagents, we conclude that the electrolytic reduction of 1,6-diiodo- and 1-chloro-6-iodohexane involves both radical and carbanion intermediates, whereas only carbanionic pathways are important for electrolyses of 1,6-dibromo- and 1-bromo-6-chlorohexane.
Mubarak, Mohammad S.,Peters, Dennis G.
p. 681 - 685
(2007/10/02)

Single Electron Transfer Mechanism in the Reaction of 1,3-Dithianyllithium and Alkyl Iodides
The reaction between 2-lithio-1,3-dithiane and optically active (R)-2-iodooctane was found to proceed with complete inversion of configuration.This result suggests that the SN2 (rather than single electron transfer (SET)) mechanism is the preferred pathway for reaction between dithianyllithium and unhindered alkyl halides.When the neopentyl-type radical probe 5,5-dimethyl-6-iodo-1-hexene was used as the substrate halide, 6-11percent cyclized alkylated product was obtained.This result suggests that when the SN2 pathway is blocked, SET mechanisms become operative to some extent, at least with iodide as the halogen.The reaction of dithianyllithium and (R)-2-iodooctane and 5,5-dimethyl-6-iodo-1-hexene, with hexane as the solvent, proceeds under heterogeneous conditions to bring about complete racemization of the respective iodide.These results demonstrate for the first time that 2-lithio-1,3-dithiane can act as electron donor in reactions initiated by electron transfer to alkyl iodides.
Juaristi, Eusebio,Jimenez-Vazquez, Hugo A.
p. 1623 - 1630
(2007/10/02)

One-Flask, Regiospecific Conversions of Allylic Alcohols into Two-Carbon-Extended, Conjugated Dienoate Esters. Use of a New Sulfinyl Orthoester
Sixteen differently substituted primary and secondary allylic alcohols are shown to react with sulfinyl orthoacetate 1 at 100 deg C sequentially via a sigmatropic rearrangement and then a β-elimination of benzenesulfenic acid to form conjugated dienoate esters 5-13 in 45-95percent yields.This one-flask, intramolecular carbon-carbon bond-forming process represents a simple and convenient method for regiospecific γ-attachment of a two-carbon (ethoxycarbonyl)methylene unit via the synthetic equivalent of an SN2' process.Two examples are given in which rationally designed dienoates 20 and 24, prepared via this one-flask process and carrying a pendant alkene unit, undergo intramolecular 2+4 cycloaddition producing bicyclic cyclohexenes 21 and 25.
Posner, Gary H.,Crouch, R. David,Kinter, Chris M.,Carry, Jean-Christophe
p. 6981 - 6987
(2007/10/02)

Preparative flash vacuum thermolysis. Selective elimination of 6-chloro-1-hexene from esters of 6-chloro-1-hexanol with Schonberg rearrangement of the S-methyl xanthate
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Jenneskens,Hoefs,Wiersum
p. 5811 - 5814
(2007/10/02)

EXCEPTIONALLY MILD AND STEREOSPECIFIC RING FRAGMENTATIONS PROMOTED BY DIMETHYLBORON BROMIDE
A stereospecific and exceptionally mild fragmentation of β-iodoethers and allylic iodoethers by Me2BBr in the presence of n-Bu4NI was developed
Gauthier, Jacques Yves,Guindon, Y.
p. 5985 - 5988
(2007/10/02)

RATE CONSTANT FOR HYDROXYLATION OF A PRIMARY ALKYL RADICAL BY INDUCED DECOMPOSITION OF AN ALPHA HYDROPEROXYALKYL DIAZENE
Rate constants for induced decomposition of 5-hexenyl(1-hydroperoxy-1-methylethyl)diazene ((CH3)2C(OOH)N=N(CH2)4CH=CH2, 2) have been estimated.Thermolysis of 2 at 50 deg C affords 5-hexenyl radicals which abstract the hydroxyl group from 2 in competition with cyclization of 5-hexenyl to cyclopentylmethyl radicals.The known rate constant (kc) for that cyclization was used to clock the bimolecular hydroxyl abstraction process.For reaction in hexafluorobenzene at 50 deg C, the rate constant for abstraction of hydroxyl from 2 (kOH) was found to be dependent on the concentration of 2.For example, at = 0.4M, kOH = 3.2*106 M-1s-1 whereas, at = 0.10 M, kOH = 1.8*107 M-1s-1.The concentration dependence of kOH is attributed to the effects of intermolecular hydrogen bonding and the large absolute values of kOH are ascribed to concerted induced decomposition, the O - O bond being broken in concert with scission of the nearest C - N bond of the azo function.The relevance of the results, to synthetic application of α-hydroperoxyalkyl diazenes in hydroxyalkylation reactions, is discussed.
Lakhani, Chandra,Mathew, Lukose,Warkentin, John
p. 1748 - 1752
(2007/10/02)

METAL-HALOGEN INTERCHANGE BETWEEN t-BUTYLLITHIUM AND 1-IODO-5-HEXENES PROVIDES NO EVIDENCE FOR SINGLE-ELECTRON TRANSFER
No products attributable to cyclization of 5-hexen-1-yl radicals have been detected in reactions of t-butyllithium with 1-iodo-5-hexenes at -78 gradC.Such experiments provide no evidence for the intermediacy of free-radicals in the metal-halogen interchange of primary alkyliodides with t-C4H9Li.
Bailey, William F.,Patricia, Jeffrey J.,Nurmi, Timo T.,Wang, Wei
p. 1861 - 1864
(2007/10/02)

DEPLACEMENTS HOMOLYTIQUES INTRAMOLECULAIRES . 12 - DECOMPOSITION INDUITE DE PEROXYDES ETHYLENIQUES : INFLUENCE DE LA LONGUEUR DE LA CHAINE
Products analyses of the thermolyses of the peroxides CH2=CH-(CH2)nOOtBu, 1, (n=1-5) showed that an induced decomposition of 1 occurred for n=1,2,3,4.Free radical additions of THF, carbon tetrachloride, bromotrichloromethane to 1 have been performed at lower temperature; they allowed, through the isolation of an adduct peroxide, at least in one case for each peroxide, to prove that a two-steps mechanism (addition of radical Z. to the double bond, intramolecular homolytic displacement) is involved in the induced decomposition of 1.The order of magnitude of the rate constants of these SHi reactions could be estimated.
Bourgeois, M. J.,Maillard, B.,Montaudon, E.
p. 5309 - 5320
(2007/10/02)