- Effective deoxygenation of fatty acids over Ni(OAc)2 in the absence of H2 and solvent
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Different metal acetate salts were systematically examined for the catalytic deoxygenation of stearic acid in the absence of H2 and solvent for the first time. Ni(OAc)2 exhibited the highest activity with 62% yield achieved at 350°C for 4.5 h with only 1 mol% (0.2 wt%) of the catalyst. Even with 0.25 mol% (0.05 wt%) catalyst, around 28% yield was achieved within 2 h at 350°C with 89% selectivity to C17 hydrocarbons. The activity based on C17 yields per Ni was 14.5 mol mol-1 h-1, considerably higher than that in previous reports. The catalytically active species were identified to be in situ generated Ni nanoparticles (8-10 nm) formed from the decomposition of the metal precursor with stearic acid as a stabilizer. A new reaction pathway of alkane formation from stearic acid via anhydride intermediate decarbonylation under an inert gas atmosphere was proposed. The excellent stability of the catalyst was demonstrated by re-adding a substrate to the system, during which the activity remained constant through four consecutive runs. The novel catalytic system was found to be applicable to a range of fatty acids and triglycerides with varying activities.
- Li, Wenjing,Gao, Yongjun,Yao, Siyu,Ma, Ding,Yan, Ning
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Read Online
- The Sphingosine and Acyl Chains of Ceramide [NS] Show Very Different Structure and Dynamics That Challenge Our Understanding of the Skin Barrier
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The lipid phase of the uppermost human skin layer is thought to comprise highly rigid lipids in an orthorhombic phase state to protect the body against the environment. By synthesizing sphingosine-d28 deuterated N-lignoceroyl-d-erythro-sphingosine (ceramide [NS]), we compare the structure and dynamics of both chains of that lipid in biologically relevant mixtures using X-ray diffraction, 2H NMR analysis, and infrared spectroscopy. Our results reveal a substantial fraction of sphingosine chains in a fluid and dynamic phase state at physiological temperature. These findings prompt revision of our current understanding of the skin lipid barrier, where an extended ceramide [NS] conformation is preferred and a possible domain structure is proposed. Mobile lipid chains may be crucial for skin elasticity and the translocation of physiologically important molecules.
- Engberg, Oskar,Huster, Daniel,Juha??ik, Martin,Ková?ik, Andrej,Opálka, Luká?,Pullmannová, Petra,Vávrová, Kate?ina
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Read Online
- Anodic Cyclization of Unsaturated α-Stannyl Ethers. Termination by Bromide derived from Dibromomethane
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Anodic oxidation of unsaturated α-stannyl ethers in Bu4NClO4-CH2Br2 results in effective cyclization and the introduction of bromide into one of the original olefinic carbons; a mechanism involving the coupling between the cyclized carbocation and Br- generated by cathodic reduction of CH2Br2 is suggested.
- Yoshida, Jun-ichi,Takada, Kazunori,Ishichi, Yuji,Isoe, Sachihiko
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Read Online
- A Method for preparing alpha-olefins from Biomass-derived fat and oil
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The present invention relates to a method for preparing alpha-olefins from biomass-derived fats and oils. According to the preparation method, all of the various saturated or unsaturated fatty acids in the biomass-derived fats and oils can be prepared into alpha-olefins, and a conventional problem that the saturated fatty acids do not participate in a reaction or a mixture is generated due to polyunsaturated fatty acids can be solved. Thus, the present invention can be advantageously used to prepare alpha-olefins from biomass.
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- Alkene synthesis by photocatalytic chemoenzymatically compatible dehydrodecarboxylation of carboxylic acids and biomass
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Direct conversion of renewable biomass and bioderived chemicals to valuable synthetic intermediates for organic synthesis and materials science applications by means of mild and chemoselective catalytic methods has largely remained elusive. Development of artificial catalytic systems that are compatible with enzymatic reactions provides a synergistic solution to this enduring challenge by leveraging previously unachievable reactivity and selectivity modes. We report herein a dual catalytic dehydrodecarboxylation reaction that is enabled by a crossover of the photoinduced acridine-catalyzed O-H hydrogen atom transfer (HAT) and cobaloxime-catalyzed C-H-HAT processes. The reaction produces a variety of alkenes from readily available carboxylic acids. The reaction can be embedded in a scalable triple-catalytic cooperative chemoenzymatic lipase-acridine-cobaloxime process that allows for direct conversion of plant oils and biomass to long-chain terminal alkenes, precursors to bioderived polymers.
- Nguyen, Vu T.,Nguyen, Viet D.,Haug, Graham C.,Dang, Hang T.,Jin, Shengfei,Li, Zhiliang,Flores-Hansen, Carsten,Benavides, Brenda S.,Arman, Hadi D.,Larionov, Oleg V.
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p. 9485 - 9498
(2019/10/11)
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- Synthesis of mesoporous ZSM-5 zeolites and catalytic cracking of ethanol and oleic acid into light olefins
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Conversion of biomass-derived chemicals into light olefins is a promising method to maintain sustainable development of light olefin industry. In this study, three mesoporous ZSM-5 zeolites (MZSM-5-A, MZSM-5-B and MZSM-5-C) with major pore diameter about 4.8 nm, 16 nm and 22 nm were synthesized using a hydrothermal method by utilizing different templates. The catalytic activity of catalysts was studied by catalytic cracking of ethanol and oleic acid. The influence of reaction temperature on conversion and product selectivity was investigated. The characterization of ZSM-5 samples showed that the orders of the external surface area and mesopore volume were MZSM-5-C > MZSM-5-B > MZSM-5-A > conventional HZSM-5. In ethanol to light olefin reaction, MZSM-5-C achieved the highest light olefin yield (318.3 mL g?1) and ethylene selectivity (42.3%) at 400 °C. In oleic acid to light olefin reaction, MZSM-5-B achieved a complete conversion of oleic acid at 500 °C, and obtained the highest light olefin selectivity (38.1%) at 550 °C. The difference may be relevant to the size and chemical structure of feedstock molecular as well as the acidity of catalysts. Regardless of ethanol or oleic acid as feedstock, introduction of mesopore in zeolites significantly enhanced the light olefin yield and selectivity.
- Zhao, Tingting,Li, Fuwei,Yu, Hongchang,Ding, Shilei,Li, Zhixia,Huang, Xinyuan,Li, Xiang,Wei, Xiaohan,Wang, Zhenlin,Lin, Hongfei
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p. 101 - 110
(2019/02/24)
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- Electron transfer-induced reduction of organic halides with amines
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Reduction of a variety of organo halides was examined by using amines as a sacrificial hydrogen source. UV light-induced reduction of vinyl and aryl halides with triethylamine proceeded smoothly to give the corresponding reduced products. High temperature heating also caused the reduction and DABCO (1,4-diazabicyclo[2.2.2]octane) also served as a good reducing reagent.
- Fukuyama, Takahide,Fujita, Yuki,Miyoshi, Hayato,Ryu, Ilhyong,Kao, Shih-Chieh,Wu, Yen-Ku
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supporting information
p. 5582 - 5585
(2018/06/04)
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- A process for the preparation and synthetic ChondriamideA and ChondriamideC method (by machine translation)
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The invention provides a process for the preparation of synthetic Chondriamide A and Chondriamide C and method, wherein the invention provides a process for the preparation, including: formula (I) compounds of structure, palladium catalyst, phosphorus ligand, alkali and organic solvent at room temperature the illumination reaction, formula (II) structure obtained olefin; wherein through the selection of a particular phosphorus ligand; make the method of the invention can be under the photocatalysis, room temperature to realize high-efficient catalytic conversion, and the mild reaction conditions, simple operation, in line with the development of green environment-friendly chemical requirements, and the range of choice of substrate and functional group compatibility has more universal, and has outstanding chemical selectivity; and the method can be successfully applied to complex molecular introducing carbon-carbon double bond to the programme, to optimize a part of the drug molecular synthesis strategy, improve the synthesis efficiency, reduce the cost, with industrial synthetic value and prospects. (by machine translation)
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Paragraph 0078-0082; 0305-0309
(2018/09/13)
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- Decarboxylative Olefination of Activated Aliphatic Acids Enabled by Dual Organophotoredox/Copper Catalysis
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Herein, we demonstrate a dual organophotoredox/copper catalytic strategy toward challenging decarboxylative olefination processes proceeding in high yields and selectivities. This operationally simple method uses photoactive organic molecules and Cu(II)-complexes as catalysts to provide rapid access to a wide variety of olefins from inexpensive synthetic and biomass-derived carboxylic acids under mild light-mediated conditions. Mechanistic investigations suggest that the reaction rate for this process is controlled solely by the incident photon flux.
- Tlahuext-Aca, Adrian,Candish, Lisa,Garza-Sanchez, R. Aleyda,Glorius, Frank
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p. 1715 - 1719
(2018/03/13)
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- An Engineered Self-Sufficient Biocatalyst Enables Scalable Production of Linear α-Olefins from Carboxylic Acids
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Fusing the decarboxylase OleTJE and the reductase domain of P450BM3 creates a self-sufficient protein, OleT-BM3R, which is able to efficiently catalyze oxidative decarboxylation of carboxylic acids into linear α-olefins (LAOs) under mild aqueous conditions using O2 as the oxidant and NADPH as the electron donor. The compatible electron transfer system installed in the fusion protein not only eliminates the need for auxiliary redox partners, but also results in boosted decarboxylation reactivity and broad substrate scope. Coupled with the phosphite dehydrogenase-based NADPH regeneration system, this enzymatic reaction proceeds with improved product titers of up to 2.51 g L-1 and volumetric productivities of up to 209.2 mg L-1 h-1 at low catalyst loadings (～0.02 mol%). With its stability and scalability, this self-sufficient biocatalyst offers a nature-friendly approach to deliver LAOs.
- Lu, Chen,Shen, Fenglin,Wang, Shuaibo,Wang, Yuyang,Liu, Juan,Bai, Wen-Ju,Wang, Xiqing
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p. 5794 - 5798
(2018/06/01)
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- Selective Decarbonylation of Fatty Acid Esters to Linear α-Olefins
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Selective decarbonylation of p-nitrophenol esters of fatty acids to the corresponding linear α-olefins (LAOs) was achieved using palladium catalysis. After extensive ligand screening, a mixed-ligand system exploiting the trans-spanning diphosphine XantPhos and an N-heterocyclic carbene (IPr) was identified as the most effective in yielding high α-selectivity and high conversions of the ester (>98% selectivity, >90% conversion using 2.5 mol % of PdCl2 and 5 mol % of the ligands, 190 °C, 2-2.5 h). On the basis of insights from modeling at the density functional level of theory, we propose that the mixed-ligand set achieves high α-selectivity by promoting olefin dissociation from the palladium center following β-hydride elimination, which is especially facilitated both by the combined steric bias of the mixed-ligand set and by the ability of the XantPhos ligand to coordinate in both mono- and bidentate fashions.
- John, Alex,Dereli, Büsra,Ortunìo, Manuel A.,Johnson, Hillis E.,Hillmyer, Marc A.,Cramer, Christopher J.,Tolman, William B.
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p. 2956 - 2964
(2017/08/21)
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- Anhydride-Additive-Free Nickel-Catalyzed Deoxygenation of Carboxylic Acids to Olefins
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A nickel-catalyzed route for direct, anhydride-additive-free deoxygenation of fatty acids to the corresponding olefins has been developed. The transformation is catalyzed by simple nickel salts of the type NiX2 (X = halide, acetate, acetylacetonate), uses PPh3 as a stoichiometric reductant, and exhibits selectivity for generation of linear α-olefin products. The reaction was rendered cocatalytic in PPh3 using 1,1,3,3-tetramethyldisiloxane (TMDS) as terminal reductant for the in situ reduction of OPPh3 and catalytic Cu(OTf)2
- John, Alex,Hillmyer, Marc A.,Tolman, William B.
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supporting information
p. 506 - 509
(2017/04/21)
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- CATALYTIC ESTER DECARBONYLATION
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A process of preparing olefins of the formula (I) is described herein: with R1 being a substituted or unsubstituted (C1-C30)hydrocarbyl, and R2 being a substituted or unsubstituted (C1-C20)hydrocarbyl. The process includes reacting a compound of formula (II) wherein Ar is chosen from in the presence of a palladium-based catalyst and an organic solvent. A process of preparing olefins of the formula (III) is also described: with R3 being a substituted or unsubstituted (C1-C30)hydrocarbyl, R4 being a substituted or unsubstituted (C1-C20)hydrocarbyl, and R5 being a substituted or unsubstituted (C1-C30) hydrocarbyl. The process includes reacting a compound of formula (IV) wherein Ar is chosen from with a compound of formula (V) wherein Ar is chosen from in the presence of a palladium-based catalyst and an organic solvent.
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Paragraph 0087-0088
(2016/08/07)
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- Development of an acid ceramidase activity-based probe
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Acid ceramidase is responsible for the ultimate step in the catabolism of (glyco)sphingolipids by hydrolysis of ceramide into sphingosine and free fatty acid. Deficiency in acid ceramidase is the molecular basis of Farber disease. Here we report the synthesis and characterization of an activity-based acid ceramidase probe.
- Ouairy, Cécile M. J.,Ferraz, Maria J.,Boot, Rolf G.,Baggelaar, Marc P.,Van Der Stelt, Mario,Appelman, Monique,Van Der Marel, Gijsbert A.,Florea, Bogdan I.,Aerts, Johannes M. F. G.,Overkleeft, Herman S.
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supporting information
p. 6161 - 6163
(2015/04/14)
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- Investigation of hydrocarbon generation mechanism by polarizing the carboxy-group of fatty acid salt with microwave radiation
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Triglycerides can be converted to renewable hydrocarbons fuel which can be used as engine fuels by alkali pyrolysis decarboxylation and cracking processes. The purpose of present study was to explore decarboxylation mechanism of fatty acid salt with microwave radiation. Sodium stearate, potassium stearate, sodium oleate and sodium laurate was chosen as a model compound. The carboxy-terminal of this dipolar molecule was further polarized with microwave radiation. The Lorentz force of ions of dipolar molecules were moved in accordance with the way of electromagnetic waves, contribute to the formation of carbanion, which effectively promote the decarboxylation reaction. Moreover, the polarity of carboxy-terminal was stronger, more easily decarboxylation. The surface of glycerol formed a High-Temperature Locus in microwave radiation reaction system, facilitate the decarboxylation processe, in adition to played a role as the hydrogen donor for this high dielectric value compound. C8-C20 n-alkanes and n-alk-1-enes were arranged regular in liquid products. It proved the feasibility to derive renewable hydrocarbon fuel from sodium salt of fatty acids by microwave pyrolysis.
- Wang,Liu,Ruan,Wen,Wan,Zhang
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p. 369 - 375
(2014/06/09)
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- PALLADIUM-CATALYZED DECARBONYLATION OF FATTY ACID ANHYDRIDES FOR THE PRODUCTION OF LINEAR ALPHA OLEFINS
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The present invention is directed to methods of forming olefins, especially linear alpha olefins from fatty acids or anhydrides, each method comprising: contacting an amount of precursor carboxylic acid anhydride with a palladium catalyst comprising a bidentate bis-phosphine ligand in a reaction mixture so as to form an olefin in a product with the concomittant formation and removal of CO and water from the reaction mixture, either directly or indirectly, wherein the reaction mixture is maintained with a sub-stoichiometric excess of a sacrificial carboxylic acid anhydride, an organic acid, or both, said sub-stoichiometric excess being relative to the amount of the precursor carboxylic acid anhydride. The precursor carboxylic acid anhydride may be added to the reaction mixture directly or formed in situ by the reaction between at least one precursor carboxylic acid with a stoichiometric amount of the sacrificial acid anhydride.
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Page/Page column
(2014/06/23)
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- Palladium-catalyzed decarbonylative dehydration of fatty acids for the production of linear alpha olefins
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A highly efficient palladium-catalyzed decarbonylative dehydration reaction of carboxylic acids is reported. This method transforms abundant and renewable even-numbered natural fatty acids into valuable and expensive odd-numbered alpha olefins. Additionally, the chemistry displays a high functional group tolerance. The process employs a low loading of palladium catalyst and proceeds under solvent-free and relatively mild conditions.
- Liu, Yiyang,Kim, Kelly E.,Herbert, Myles B.,Fedorov, Alexey,Grubbs, Robert H.,Stoltz, Brian M.
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supporting information
p. 130 - 136
(2014/03/21)
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- Method for Allylating and Vinylating Aryl, Heteroaryl, Alkyl, and Alkene Halogenides Using Transition Metal Catalysis
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What is described is a process for preparing organic compounds of the general formula (I) R—R′??(I) by converting a corresponding compound of the general formula (II) R—X ??(II) in which X is fluorine, chlorine, bromine or iodine to an organomagnesium compound of the general formula (III) [M+]n[RmMgXkY1]??(III) wherein compounds of the formula (III) are reacted with a compound of the general formula (IV) characterized in that the reaction of (III) with (IV) is performed in the presence of a) catalytic amounts of an iron compound, based on the compound of the general formula (II), and optionally in the presence of b) a nitrogen-, oxygen- and/or phosphorus-containing additive in a catalytic or stoichiometric amount, based on the compound of the general formula (II).
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Paragraph 0062; 0063; 0065; 0066
(2013/07/25)
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- Iron-catalyzed decarbonylation reaction of aliphatic carboxylic acids leading to α-olefins
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The catalytic decarbonylation reaction of aliphatic carboxylic acids can be carried out in the presence of an iron complex, and it proceeds smoothly to give α-olefins with high selectivity. The Royal Society of Chemistry 2012.
- Maetani, Shinji,Fukuyama, Takahide,Suzuki, Nobuyoshi,Ishihara, Daisuke,Ryu, Ilhyong
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scheme or table
p. 2552 - 2554
(2012/03/26)
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- Facile regio- and stereoselective hydrometalation of alkynes with a combination of carboxylic acids and group 10 transition metal complexes: Selective hydrogenation of alkynes with formic acid
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A facile, highly stereo- and regioselective hydrometalation of alkynes generating alkenylmetal complex is disclosed for the first time from a reaction of alkyne, carboxylic acid, and a zerovalent group 10 transition metal complex M(PEt3)4 (M = Ni, Pd, Pt). A mechanistic study showed that the hydrometalation does not proceed via the reaction of alkyne with a hydridometal generated by the protonation of a carboxylic acid with Pt(PEt 3)4, but proceeds via a reaction of an alkyne coordinate metal complex with the acid. This finding clarifies the long proposed reaction mechanism that operates via the generation of an alkenylpalladium intermediate and subsequent transformation of this complex in a variety of reactions catalyzed by a combination of Bronsted acid and Pd(0) complex. This finding also leads to the disclosure of an unprecedented reduction of alkynes with formic acid that can selectively produce cis-, trans-alkenes and alkanes by slightly tuning the conditions.
- Shen, Ruwei,Chen, Tieqiao,Zhao, Yalei,Qiu, Renhua,Zhou, Yongbo,Yin, Shuangfeng,Wang, Xiangbo,Goto, Midori,Han, Li-Biao
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supporting information; experimental part
p. 17037 - 17044
(2011/12/04)
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- Efficient iridium-catalyzed decarbonylation reaction of aliphatic carboxylic acids leading to internal or terminal alkenes
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Vaska's complex, IrCl(CO)(PPh3)2, when combined with KI as an additive, served as an excellent catalyst for the decarbonylation of long-chain aliphatic carboxylic acids to give internal alkenes with high selectivity. On combination with KI and Ac2O as additives under controlled temperatures, decarbonylation proceeded to give terminal alkenes with high selectivity.
- Maetani, Shinji,Fukuyama, Takahide,Suzuki, Nobuyoshi,Ishihara, Daisuke,Ryu, Ilhyong
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experimental part
p. 1389 - 1394
(2011/04/25)
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- Efficient silver-catalyzed regio- and stereospecific aziridination of dienes
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Nitrene transfer: Unsymmetric dienes bearing a terminal hydroxy group can be regio- and stereospecifically converted into vinylaziridines upon nitrene transfer from PhINTs using a silver-based catalyst. Stoichiometric mixtures of dienes and PhINTs were employed at low catalyst loadings (0.5□%; see scheme). The method has been applied to the synthesis of (±)-sphingosine and gave good yields in a three-step procedure. Ts=4-toluenesulfonyl.
- Llaveria, Josep,Beltran, Alvaro,Diaz-Requejo, M. Mar,Perez, Pedro J.,Matheu, M. Isabel,Castillon, Sergio
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supporting information; experimental part
p. 7092 - 7095
(2010/11/05)
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- Regioselective functionalization of alkanes by sequential dehydrogenation-hydrozirconation
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We have succeeded in formal regioselective functionalization of alkanes by iridium-catalyzed dehydrogenation, hydrozirconation of the resulting alkenes, and electrophilic reaction of the generated alkylzirconium intermediate.
- Kuninobu, Yoichiro,Ureshino, Tomonari,Yamamoto, Shun-Ichi,Takai, Kazuhiko
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supporting information; experimental part
p. 5310 - 5312
(2010/10/21)
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- Synthesis of (+)-Sch 642305 by a biomimetic transannular Michael reaction
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The synthesis of (+)-Sch 642305 (1) has been completed in 17 steps in 1.6% overall yield. Transannular Michael reaction of 2b with NaH in THF provided cyclohexenone 23 stereospecifically. Heating 23 in TFA/CDCI3 provided a 3:1 equilibrium mixture of 23 and 25, which was hydrolyzed to give (+)-6-epi-Sch 642305 (24) and (+)-Sch 642305 (1), respectively.
- Snider, Barry B.,Zhou, Jingye
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p. 1283 - 1286
(2007/10/03)
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- Semivolatile and volatile compounds in combustion of polyethylene
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The evolution of semivolatile and volatile compounds in the combustion of polyethylene (PE) was studied at different operating conditions in a horizontal quartz reactor. Four combustion runs at 500 and 850°C with two different sample mass/air flow ratios and two pyrolytic runs at the same temperatures were carried out. Thermal behavior of different compounds was analyzed and the data obtained were compared with those of literature. It was observed that α,ω-olefins, α-olefins and n-paraffins were formed from the pyrolytic decomposition at low temperatures. On the other hand, oxygenated compounds such as aldehydes were also formed in the presence of oxygen. High yields were obtained of carbon oxides and light hydrocarbons, too. At high temperatures, the formation of polycyclic aromatic hydrocarbons (PAHs) took place. These compounds are harmful and their presence in the combustion processes is related with the evolution of pyrolytic puffs inside the combustion chamber with a poor mixture of semivolatile compounds evolved with oxygen. Altogether, the yields of more than 200 compounds were determined. The collection of the semivolatile compounds was carried out with XAD-2 adsorbent and were analyzed by GC-MS, whereas volatile compounds and gases were collected in a Tedlar bag and analyzed by GC with thermal conductivity and flame ionization detectors.
- Font, Rafael,Aracil, Ignacio,Fullana, Andrés,Conesa, Juan A.
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p. 615 - 627
(2007/10/03)
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- Synthesis of amphiphilic thiatrimethinecyanines
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Preparation conditions were optimized for 2-methyl-5-chlorobenzothiazolium quaternary salts with long-chain N-alkyl substituents (C12H 25, C15H31, C18H37). They were used in the synthesis of thiatrimethinecyanines conteining in the meso-position phenyl, p-chlorophenyl, or p-fluorophenyl groups.
- Orlova,Kolchina,Shakirov,Gerasimova,Shelkovnikov
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p. 228 - 231
(2007/10/03)
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- A mild and efficient protocol for the conversion of carboxylic acids to olefins by a catalytic decarbonylative elimination reaction
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A new method for the conversion of aliphatic carboxylic acids to olefins under unprecedented mild conditions is disclosed, wherein the carboxylic acids are converted in situ with pivalic anhydride to the mixed anhydrides, which regioselectively add to a PdCl2-DPE-Phos catalyst. At a temperature of only 110°C, smooth decarbonylation and β-hydride elimination occur, and the corresponding olefins along with CO, CO2 and pivalic acid are liberated.
- Goossen, Lukas J.,Rodriguez, Nuria
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p. 724 - 725
(2007/10/03)
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- Palladium-catalyzed negishi cross-coupling reactions of unactivated alkyl iodides, bromides, chlorides, and tosylates
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A single method (2% Pd2(dba)3/8% PCyp 3/NMI in THF/NMP at 80°C; Cyp = cyclopentyl) achieves the cross-coupling of a range of β-hydrogen-containing primary alkyl iodides, bromides, chlorides, and tosylates with an array of alkyl-, alkenyl-, and arylzinc halides. The process is compatible with a variety of functional groups, including esters, amides, imides, nitriles, and heterocycles.
- Zhou, Jianrong,Fu, Gregory C.
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p. 12527 - 12530
(2007/10/03)
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- Synthesis of 2,2′-quinocyanines with long N-alkyl substituents
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2,2′-Quinocyanines with long alkyl substituents on one or both nitrogen atoms have been synthesized. 1H NMR spectroscopy has been used to study the processes occurring during the alkylation of the starting quinoline bases.
- Orlova,Kolchina,Zhuravlev,Shakirov,Gerasimova,Shelkovnikov
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p. 1233 - 1241
(2007/10/03)
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- Pinacolboratamethyl-enetriphenylphosphonium iodide, a new methylene transfer reagent
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The title compound is easily prepared and reacts with various aldehydes and ketone. The reagent is compatible with free hydroxy groups. Yields with various aldehydes and ketones are in 50- > 99% range. Both aliphatic, aromatic and unsaturated carbonyls react.
- Al-Aziz Quntar, Abed,Srebnik, Morris
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p. 2575 - 2579
(2007/10/03)
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- Scope and utility of a new soluble copper catalyst [CuBr-LiSPh-LiBr-THF]: A comparison with other copper catalysts in their ability to couple one equivalent of a Grignard reagent with an alkyl sulfonate
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A mixture of equal amounts of CuBr-SMe2, LiBr, and LiSPh in THF at 0°C furnished a new soluble copper catalyst that was highly efficient at coupling primary, secondary, tertiary, aryl, vinyl, and allylic Grignard reagents to primary tosylates and primary Grignard reagents to secondary tosylates and mesylates, all with the use of only 1 equiv of Grignard reagent. The new catalyst was shown to be much more reactive than copper catalysts CuBr and Li2CuCl4 and more efficient in the transference of secondary and tertiary alkyl groups than lower order cuprates (Gilman reagents) and demonstrated more reactivity than the lower order cuprates with its ability to couple primary Grignard reagents to secondary sulfonates. The Grignard reagent/catalyst system was compatible with an ester functionalized tosylate, thus proving to be more chemoselective than a Grignard reagent without the catalyst. The catalyst exhibited good reactivity below room temperature, and with the addition of 6% v/v of HMPA to the catalyst solution, excellent yields of coupled product were obtained within a 25-67°C temperature range. 1H NMR demonstrated that the catalyst solution consisted of several species that most likely were composed of copper ligated with thiophenol, THF, and LiBr in aggregated forms.
- Burns, Dennis H.,Miller, Jeffrey D.,Chan, Ho-Kit,Delaney, Michael O.
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p. 2125 - 2133
(2007/10/03)
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- Utilization of tetrabutylammonium triphenyldifluorosilicate as a fluoride source for silicon-carbon bond cleavage
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Tetrabutylammonium triphenyldifluorosilicate (TBAT) can be employed as a fluoride source to cleave silicon-carbon bonds thus generating in situ carbanions that coupled with a variety of electrophiles, including aldehydes and ketones, in moderate to high yields. Among the examples reported is the first instance of fluoride-induced intermolecular coupling between allyltrimethylsilane and imine derivatives. Also, of particular note is the TBAT-initiated coupling of primary alkyl halides with allyltrimethylsilane. TBAT is an easily handled crystalline solid that has several advantages over tetrabutylammonium fluoride (TBAF) as a fluoride source; it is anhydrous, nonhygroscopic, soluble in most commonly used organic solvents, and less basic than TBAF.
- Pilcher, Anthony S.,DeShong, Philip
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p. 6901 - 6905
(2007/10/03)
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- Sulfur ylide vinylation of halides and mesylates
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One-carbon homologation of benzylic, allylic, propargylic and primary halides or mesylates with dimethylsulfonium methylide affords terminal olefins in good to excellent yields.
- Alcaraz,Harnett,Mioskowski,Martel,Le Gall,Shin, Dong-Soo,Falck
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p. 5453 - 5456
(2007/10/02)
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- LIQUID-CRYSTALLINE SOLVENTS AS MECHANISTIC PROBES. 23. NORRISH II REACTIONS OF 2- AND SYM-ALKANONES IN THE ISOTROPIC, SMECTIC B, AND CRYSTALLINE PHASES OF n-BUTYL STEARATE.
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n-Alkanones with the carbonyl group at the 2 or central positions (1 and 2, respectively) have been irradiated in the isotropic, smectic B, and two solid phases of n-butyl stearate (BS).The lengths of the ketones were varied from 11 to 31 carbons.The ratios of elimination/cyclization products and diastereomeric cyclobutanol products were measured for each as a function of temperature and BS phase.The effect of 1 and 2 on the phase transition temperatures of BS has been correlated with changes in the product ratios.The experiments demonstrate that a very sensitive cooperative relationship exists between the ease with which 1 and 2 fit into the ordered phases of BS and the degree to which the solvent matrices influence ketone photochemistry.The influence of solvent order on the product ratios is distinctly different for 1 and 2, and for the two product ratios from one ketone.
- Treanor, Richard L.,Weiss, Richard G.
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p. 1371 - 1392
(2007/10/02)
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- SELECTIVE MIXED COUPLING OF CARBOXYLIC ACIDS (II). -PHOTOLYSIS OF UNSYMMETRICAL DIACYLPEROXIDES WITH ALKENYL-, HALO-, KETO-, CARBOXYL-GROUPS AND A CHIRAL α-CARBON. COMPARISON WITH THE MIXED KOLBE ELECTROLYSIS.
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- Alkenoyl and functionalized alkanoyl dodecanoyl peroxides are prepared in 70 to 97 percent yield and photolyzed at -78 deg C.Thereby 4- to 10-alkenoyl and 4-alkynoyl peroxides afford good yields (56 - 68 percent) of unsymmetrical coupling products.Similarly α- to δ-haloalkanoyl, cholanoyl or 3- and 4-carboxyalkanoyl peroxides can be coupled (40 - 70 percent).The α-chiral diacyl peroxide 1s undergoes the photochemical coupling reaction with 80 percent retention of its configuration.The photolysis of diacyl peroxides at -78 deg C proves to be a favorable supplement of the Kolbe-electrolysis in cases, where the electrolysis fails or produces low yields.
- Feldhues, Michael,Schaefer, Hans J.
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p. 4213 - 4236
(2007/10/02)
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- OLEFIN SYNTHESIS BY REACTION OF ALKYL PHENYL TELLURIDES WITH CHLORAMINE-T
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Alkyl phenyl tellurides reacted with chloramine-T in refluxing tetrahydrofuran to give olefins in high yields.
- Otsubo, Tetsuo,Ogura, Fumio,Yamaguchi, Hachiro,Higuchi, Hiroyuki,Sakata, Yoshiteru,Misumi, Soichi
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p. 447 - 448
(2007/10/02)
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