- Mesoionic N-heterocyclic olefin catalysed reductive functionalization of CO2for consecutiveN-methylation of amines
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A mesoionic N-heterocyclic olefin (mNHO) was introduced as a metal-free catalyst for the reductive functionalization of CO2leading to consecutive doubleN-methylation of primary amines in the presence of 9-borabicyclo[3.3.1]nonane (9-BBN). A wide range of secondary amines and primary amines were successfully methylated under mild conditions. The catalyst sustained over six successive cycles ofN-methylation of secondary amines without compromising its activity, which encouraged us to check its efficacy towards doubleN-methylation of primary amines. Moreover, this method was utilized for the synthesis of two commercially available drug molecules. A detailed mechanistic cycle was proposed by performing a series of control reactions along with the successful characterisation of active catalytic intermediates either by single-crystal X-ray study or by NMR spectroscopic studies in association with DFT calculations.
- Das, Arpan,Maji, Subir,Mandal, Swadhin K.
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p. 12174 - 12180
(2021/09/28)
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- Borane-Trimethylamine Complex as a Reducing Agent for Selective Methylation and Formylation of Amines with CO2
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We report herein that a borane-trimethylamine complex worked as an efficient reducing agent for the selective methylation and formylation of amines with 1 atm CO2 under metal-free conditions. 6-Amino-2-picoline serves as a highly efficient catalyst for the methylation of various secondary amines, whereas in its absence, the formylation of primary and secondary amines was achieved in high yield with high chemoselectivity. Mechanistic studies suggest that the 6-amino-2-picoline-borane catalytic system operates like an intramolecular frustrated Lewis pair to activate CO2.
- Zhang, Yanmeng,Zhang, He,Gao, Ke
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supporting information
p. 8282 - 8286
(2021/10/25)
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- Catalyst-free selective: N -formylation and N -methylation of amines using CO2 as a sustainable C1 source
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We herein describe catalyst-free selective N-formylation and N-methylation of amines using CO2 as a sustainable C1 source. By tuning the reaction solvent and temperature, the selective synthesis of formamides and methylamines is achieved in good to excellent yields using sodium borohydride (NaBH4) as a sustainable reductant.
- Zou, Qizhuang,Long, Guangcai,Zhao, Tianxiang,Hu, Xingbang
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supporting information
p. 1134 - 1138
(2020/03/11)
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- UiO-type metal-organic frameworks with NHC or metal-NHC functionalities for: N-methylation using CO2 as the carbon source
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We demonstrate the first metal-organic framework (MOF) that catalyzes N-methylation of amines using 1 atm CO2 and phenylsilane under ambient conditions. Compared with its homogeneous analog, the incorporation of N-heterocyclic carbene (NHC) into the MOF provides more efficient catalysis with improved reaction kinetics, turnover numbers and recyclability. Moreover, the metalated NHC functionalized MOF achieves direct N-methylation of amines bearing carboxylate moieties, which are common building blocks in pharmaceutical chemistry.
- Zhang, Xu,Jiang, Yilin,Fei, Honghan
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supporting information
p. 11928 - 11931
(2019/10/11)
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- Selective formylation or methylation of amines using carbon dioxide catalysed by a rhodium perimidine-based NHC complex
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Carbon dioxide can play a vital role as a sustainable feedstock for chemical synthesis. To be viable, the employed protocol should be as mild as possible. Herein we report a methodology to incorporate CO2 into primary, secondary, aromatic or alkyl amines catalysed by a Rh(i) complex bearing a perimidine-based NHC/phosphine pincer ligand. The periminide-based ligand belongs to a class of 6-membered NHC ligand accessed through chelate-assisted double C-H activation. N-Formylation and -methylation of amines were performed using a balloon of CO2, and phenylsilane as the reducing agent. Product selectivity between formylated and methylated products was tuned by changing the solvent, reaction temperature and the quantity of phenylsilane used. Medium to excellent conversions, as well as tolerance to a range of functional groups, were achieved. Stoichiometric reactions with reactants employed in catalysis and time course studies suggested that formylation and methylation reactions of interest begin with hydrosilylation of CO2 followed by reaction with amine substrates.
- Lam, Raphael H.,McQueen, Caitlin M. A.,Pernik, Indrek,McBurney, Roy T.,Hill, Anthony F.,Messerle, Barbara A.
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supporting information
p. 538 - 549
(2019/02/14)
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- Use for Boron Formates for Reducing Unsaturated Organic Functions
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The present invention relates to a method for reducing unsaturated organic compounds chosen from the group formed by the aldehydes, the ketones, the imines, the carboxylic acids, the amides, and the esters with a boron formate having the formula (I) in the presence of a solvent and optionally a base. The invention also relates to the use of the method for reducing unsaturated organic compounds chosen from the group formed by the aldehydes, the ketones, the imines, the carboxylic acids, the amides, and the esters according to the invention in the preparation of methanol, methylated amines, formaldehyde and alcohols; for the preparation of reactants for Suzuki coupling reactions; and in the manufacturing of vitamins, pharmaceutical products, glues, acrylic fibres, synthetic leather, pesticides.
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Paragraph 0254-0258; 0261
(2018/12/04)
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- Diverse catalytic reactivity of a dearomatized PN3P?-nickel hydride pincer complex towards CO2 reduction
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A dearomatized PN3P?-nickel hydride complex has been prepared using an oxidative addition process. The first nickel-catalyzed hydrosilylation of CO2 to methanol has been achieved, with unprecedented turnover numbers. Selective methylation and formylation of amines with CO2 were demonstrated by such a PN3P?-nickel hydride complex, highlighting its versatile functions in CO2 reduction.
- Li, Huaifeng,Gon?alves, Théo P.,Zhao, Qianyi,Gong, Dirong,Lai, Zhiping,Wang, Zhixiang,Zheng, Junrong,Huang, Kuo-Wei
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supporting information
p. 11395 - 11398
(2018/10/20)
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- Catalyst-free N-methylation of amines using CO2
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Recently, utilizing CO2 as a methylation reagent to construct functional chemicals has attracted significant attention. However, the conversion of CO2 is still a challenge due to its inherent inertness. In this study, we have developed a catalyst-free N-methylation of amines to prepare numerous methylamines using CO2 as a methyl source. By utilizing 2 eq. PhSiH3 as the reductant, amines could undergo N-methylation under 1 atm of CO2 in DMF at 90 °C. Aliphatic and aromatic amines were compatible, generating the desired products in up to 95% yield.
- Niu, Huiying,Lu, Lijun,Shi, Renyi,Chiang, Chien-Wei,Lei, Aiwen
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supporting information
p. 1148 - 1151
(2017/02/05)
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- Metal-free disproportionation of formic acid mediated by organoboranes
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In the presence of dialkylboranes, formic acid can be converted to formaldehyde and methanol derivatives without the need for an external reductant. This reactivity, in which formates serve as the sole carbon and hydride sources, represents the first exam
- Chauvier, Clément,Thuéry, Pierre,Cantat, Thibault
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p. 5680 - 5685
(2016/09/04)
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- One-pot three-component synthesis of quinazolines: Via a copper-catalysed oxidative amination reaction
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A copper-catalysed three-component reaction for constructing a series of quinazoline derivatives has been developed. In this system, solvents act as the reactants and different functional groups are well tolerated to obtain corresponding products in moderate to good yields.
- Duan, Tiantian,Zhai, Tianran,Liu, Huanhuan,Yan, Zilong,Zhao, Yue,Feng, Lei,Ma, Chen
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p. 6561 - 6567
(2016/07/16)
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- PROCESS FOR PRODUCING N-METHYL OR N,N-DIMETYL AMINES
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A process for producing N-methyl or N,N-dimethyl amines, which comprises using amine compound, nitro-containing compound or nitrile compound as a starting material, carbon dioxide as a methylating agent and hydrogen gas as a reducing agent, and allowing them to react in a sealed reactor for 6 to 48 h in a reaction medium at a reaction temperature of 80 to 180 ° C. in the presence of a composite catalyst, so as to provide N-methyl or N,N-dimethyl amines. The process of the present invention is simple and under relative mild reaction conditions. By means of the process of the invention, the target products can be prepared at low cost with a high yield. The catalysts used have a high catalytic activity and can be separated from the reaction system simply and reused. Furthermore, the whole process of the present invention is environmental-friendly and facilitates the cycling use of carbon dioxide.
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Paragraph 0059
(2015/02/18)
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- Transition metal-free methylation of amines with formaldehyde as the reductant and methyl source
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A simple transition metal-free procedure using formaldehyde for the N,N-dimethylation and N-methylation of primary and secondary anilines is reported. The reaction showed limitations on sterically hindered and electron-withdrawing anilines, but is successful on amines with electron-donating substituents. Formaldehyde acts as both the reducing agent and the carbon source in the reaction.
- Man, Nikki Y.T.,Li, Wanfang,Stewart, Scott G.,Wu, Xiao-Feng
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p. 345 - 347
(2015/11/25)
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- Hydrophosphination of CO2 and Subsequent Formate Transfer in the 1,3,2-Diazaphospholene-Catalyzed N-Formylation of Amines
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Hydrophosphination of CO2 with 1,3,2-Diazaphospholene (NHP-H; 1) afforded phosphorus formate (NHP-OCOH; 2) through the formation of a bond between the electrophilic phosphorus atom in 1 and the oxygen atom from CO2, along with hydride transfer to the carbon atom of CO2. Transfer of the formate from 2 to Ph2SiH2 produced Ph2Si(OCHO)2 (3) in a reaction that could be carried out in a catalytic manner by using 5 mol % of 1. These elementary reactions were applied to the metal-free catalytic N-formylation of amine derivatives with CO2 in one pot under ambient conditions.
- Chong, Che Chang,Kinjo, Rei
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supporting information
p. 12116 - 12120
(2015/10/12)
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- Expanding the Ligand Framework Diversity of Carbodicarbenes and Direct Detection of Boron Activation in the Methylation of Amines with CO2
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A simple and convergent synthetic strategy used to increase the diversity of the carbodicarbene ligand framework through incorporation of unsymmetrical pendant groups is reported. Structural analysis and spectroscopic studies of ligands and their Rh complexes are reported. Reactivity studies reveal carbodicarbenes as competent organocatalysts for amine methylation using CO2 as a synthon. A unique B-H-activated boron-carbodicarbene complex was isolated as a reaction intermediate, providing mechanistic insight into the CO2 functionalization process.
- Chen, Wen-Ching,Shen, Jiun-Shian,Jurca, Titel,Peng, Chun-Jung,Lin, Yen-Hsu,Wang, Yi-Ping,Shih, Wei-Chih,Yap, Glenn P. A.,Ong, Tiow-Gan
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supporting information
p. 15207 - 15212
(2016/01/25)
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- N-Methylation of amine and nitro compounds with CO2/H2 catalyzed by Pd/CuZrOx under mild reaction conditions
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An active Pd/ZrCuOx catalyst was prepared for the reductive amination of CO2. The N-methylation of amines and nitro compounds with CO2/H2 can be realized with up to 97% yield under relatively mild reaction condi
- Cui, Xinjiang,Zhang, Yan,Deng, Youquan,Shi, Feng
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supporting information
p. 13521 - 13524
(2015/01/09)
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- Carbon Dioxide Reduction to Methylamines under Metal-Free Conditions
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The first metal-free catalysts are reported for the methylation of amines with carbon dioxide. Proazaphosphatrane superbases prove to be highly active catalysts in the reductive functionalization of CO2, in the presence of hydroboranes. The new methodology enables the methylation of N-H bonds in a wide variety of amines, including secondary amines, with increased chemoselectivity. Organocatalysis: Proazaphosphatrane superbases prove to be highly active catalysts in the reductive functionalization of CO2, in the presence of hydroboranes. The new method makes possible the methylation of N-H bonds in a wide variety of amines, including secondary amines (see picture), with increased chemoselectivity.
- Blondiaux, Enguerrand,Pouessel, Jacky,Cantat, Thibault
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p. 12186 - 12190
(2016/02/23)
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- Taking the F out of FLP: Simple lewis acid-base pairs for mild reductions with neutral boranes via borenium ion catalysis
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Discrete three-coordinate borenium salts 1c and 1d are accessed by cooperative Lewis acid-base pair-mediated heterolytic splitting of the B-H bond in pinacolborane by B(C6F5)3DABCO and Ph 3C+/DABCO, respectively. The resulting salts are competent catalysts in the reduction of a broad range of imines and can be generated in situ. Moreover, a mechanistic framework for borenium catalysis based on experimental evidence is proposed. The reaction is suggested to proceed by borenium activation of the imine substrate followed by counterintuitive hydride delivery from HBPin (with the assistance of DABCO) rather than from the HB(C6F5)3- anion, contrary to typical mechanisms of reduction in FLP systems.
- Eisenberger, Patrick,Bailey, Adrian M.,Crudden, Cathleen M.
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supporting information
p. 17384 - 17387
(2013/01/15)
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- Structural and reactivity comparison of analogous organometallic Pd(iii) and Pd(iv) complexes
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The tetradentate ligands RN4 (RN4 = N,N′-di-alkyl-2,11-diaza[3,3](2,6)pyridinophane, R = Me or iPr) were found to stabilize cationic (RN4)PdMe2 and ( RN4)PdMeCl complexes in both PdIII and PdIV oxidation states. This allows for the first time a direct structural and reactivity comparison of the two Pd oxidation states in an identical ligand environment. The PdIII complexes exhibit a distorted octahedral geometry, as expected for a d7 metal center, and display unselective C-C and C-Cl bond formation reactivity. By contrast, the PdIV complexes have a pseudo-octahedral geometry and undergo selective non-radical C-C or C-Cl bond formation that is controlled by the ability of the complex to access a five-coordinate intermediate. The Royal Society of Chemistry 2012.
- Tang, Fengzhi,Qu, Fengrui,Khusnutdinova, Julia R.,Rath, Nigam P.,Mirica, Liviu M.
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p. 14046 - 14050
(2013/01/15)
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- New deoxygenation method for amine n-oxides using dimethylthiocarbamoyl chloride
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A facile and efficient deoxygenation method for various amine N-oxides to their corresponding amines is described. The experimental procedure is quite simple and the products are obtained in excellent yields. Copyright Taylor & Francis Group, LLC.
- Caliskan, Hafize,Zaim, Oemer
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experimental part
p. 3078 - 3083
(2010/11/04)
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- Reactions of Sulfoxides with Magnesium Amides. Transformations of Sulfoxides into Sulfides, Dithioacetals and Vinyl Sulfides
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The reactions of sulfoxides with magnesium amides generated in situ from the reaction of ethylmagnesium bromide and seconday amines, such as diisopropylamine (DIPA) or 2,2,6,6-tetramethylpiperidine (TMP) in diethyl ether, were examined.Diaryl sulfoxides were heated with the diisopropylaminomagnesium reagent in diethyl ether to give the corresponding diaryl sulfides in 42-52percent yields.Sulfoxides bearing hydrogens at the α-position only(RSOCH2R1) reacted with the tetramethylpiperidinomagnesium reagent at room temperature to produce the corresponding dithioacetals (RSCHR1SR) in 47-86percent yields.The treatment of sulfoxides bearing hydrogens both at the α-and β-positions (RSOCHR1CHR2R3) with the magnesium amides at room temperature afforded the corresponding vinyl sulfides (RSCR1=CR2R3) in 52-72percent yields accompanying 2.3-27percent yields of the corresponding dithioacetals.The pathways leading to the products involving the formation of the sulfur-stabilized carbonium ion intermediates are discussed.
- Kobayashi, Kazuhiro,Kawakita, Masataka,Yokota, Kouichi,Mannami, Tohru,Yamamoto, Koji,et al.
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p. 1401 - 1408
(2007/10/02)
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- Transient Alkylaminium Radicals in n-Hexane. Condensed-Phase Ion-Molecule Reactions
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Time-resolved fluorescence detected magnetic resonance (FDMR) is used to observe alkylaminium radicals formed in n-hexane solutions by electron pulse radiolysis.The ease of observation of aminium radical FDMR signals increases with increasing alkyl substitution of the amine solutes.The results are discussed in terms of the ion-molecule reactions, such as proton transfer, which compete with electron-transfer processes, i. e., the electron transfer from solute molecules to n-hexane radical cations and geminate recombination.
- Werst, D. W.,Trifunac, A. D.
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p. 1268 - 1274
(2007/10/02)
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- Relaxation Processes in the N-Methyl Group of 1,2,2,6,6-Pentamethylpiperidine
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Relaxation times (T1) and methyl-methyl nuclear Overhauser effects were measured for 1H, 13C and 2H nuclei in 1,2,2,6,6-pentamethylpiperidine and its H-CHD2 analogue which was synthesized by LiAlD4 reduction of the N-CHO compound.The relaxation pathways for hydrogens of the N-CH3 group were estimated to be as follows: spin-rotation 0.046 s-1, dipole-dipole within N-methyl 0.069 s-1, and dipole-dipole with the hydrogens of the C-methyls 0.027 s-1.The 1H Overhauser effect at the N-CH3 was 7.6percent.
- Rae, Ian D.,Woolcock, Mark L.
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p. 447 - 450
(2007/10/02)
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- Method of manufacturing ketones
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The invention relates to a method for the manufacture of ketones which comprises oxidizing an n-olefin in the presence of a catalyst containing palladium, copper, a halogen, and at least one of specific tertiary amines.
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- Kinetic and Equilibrium Solvent Isotope Effects on the Deprotonation of a Salicylate Ion by Hydroxide Ion and General Bases
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Kinetic and equilibrium solvent isotope effects has been measured for proton transfer from 4-(3-nitrophenylazo)-salicylate ion (HA) to general bases (B) to examine whether a primary kinetic isotope effect is observed when proton transfer is occurring between bases of roughly equal strength for which ΔpK = pKHA - pKBH(1+) = 0.The kinetic solvent isotope effects for catalysis by three tertiary amines (ΔpK -0.85, -0.27, and +0.28) are kBH2O/kBD2O 2.0 +/-0.3, and 1.7 +/-0.2.Since for proton transfer to hydroxide ion (ΔpK -5.0) the isotope effect has a value kOH(1-)H2O(1-)/kOD(1-)D2O of 1.5 +/-0.1, the primary isotope effect for these proton transfers must be small and independent of base strength over the range studied.An explanation in terms of the reaction mechanisms is given.
- Hibbert, Frank
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p. 1304 - 1308
(2007/10/02)
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- Reduction of 4-oxo-tetraalkylpiperidines
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Process for the reduction of 4-oxo-2,2,6,6-tetraalkylpiperidines, and the N-alkyl derivatives thereof, to 2,2,6,6-tetraalkylpiperidines unsubstituted in the 4-position, wherein the reduction is carried out with catalytically activated hydrogen in an acid medium.
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