- Clean protocol for deoxygenation of epoxides to alkenes: Via catalytic hydrogenation using gold
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The epoxidation of olefin as a strategy to protect carbon-carbon double bonds is a well-known procedure in organic synthesis, however the reverse reaction, deprotection/deoxygenation of epoxides is much less developed, despite its potential utility for the synthesis of substituted olefins. Here, we disclose a clean protocol for the selective deprotection of epoxides, by combining commercially available organophosphorus ligands and gold nanoparticles (Au NP). Besides being successfully applied in the deoxygenation of epoxides, the discovered catalytic system also enables the selective reduction N-oxides and sulfoxides using molecular hydrogen as reductant. The Au NP catalyst combined with triethylphosphite P(OEt)3 is remarkably more reactive than solely Au NPs. The method is not only a complementary Au-catalyzed reductive reaction under mild conditions, but also an effective procedure for selective reductions of a wide range of valuable molecules that would be either synthetically inconvenient or even difficult to access by alternative synthetic protocols or by using classical transition metal catalysts. This journal is
- Fiorio, Jhonatan L.,Rossi, Liane M.
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p. 312 - 318
(2021/01/29)
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- Metal-Free Deoxygenation of Amine N-Oxides: Synthetic and Mechanistic Studies
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We report herein an unprecedented combination of light and P(III)/P(V) redox cycling for the efficient deoxygenation of aromatic amine N-oxides. Moreover, we discovered that a large variety of aliphatic amine N-oxides can easily be deoxygenated by using only phenylsilane. These practically simple approaches proceed well under metal-free conditions, tolerate many functionalities and are highly chemoselective. Combined experimental and computational studies enabled a deep understanding of factors controlling the reactivity of both aromatic and aliphatic amine N-oxides.
- Lecroq, William,Schleinitz, Jules,Billoue, Mallaury,Perfetto, Anna,Gaumont, Annie-Claude,Lalevée, Jacques,Ciofini, Ilaria,Grimaud, Laurence,Lakhdar, Sami
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p. 1237 - 1242
(2021/06/01)
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- Practical and Regioselective Synthesis of C-4-Alkylated Pyridines
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The direct position-selective C-4 alkylation of pyridines has been a long-standing challenge in heterocyclic chemistry, particularly from pyridine itself. Historically this has been addressed using prefunctionalized materials to avoid overalkylation and mixtures of regioisomers. This study reports the invention of a simple maleate-derived blocking group for pyridines that enables exquisite control for Minisci-type decarboxylative alkylation at C-4 that allows for inexpensive access to these valuable building blocks. The method is employed on a variety of different pyridines and carboxylic acid alkyl donors, is operationally simple and scalable, and is applied to access known structures in a rapid and inexpensive fashion. Finally, this work points to an interesting strategic departure for the use of Minisci chemistry at the earliest possible stage (native pyridine) rather than current dogma that almost exclusively employs Minisci chemistry as a late-stage functionalization technique.
- Baran, Phil S.,Choi, Jin,Godineau, Edouard,Laudadio, Gabriele
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p. 11927 - 11933
(2021/08/20)
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- Generation of Functionalized Alkyl Radicals via the Direct Photoexcitation of 2,2′-(Pyridine-2,6-diyl)diphenol-Based Borates
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A new type of alkylborate was developed for the purpose of generating radicals via direct photoexcitation. These borates were prepared using 2,2′-(pyridine-2,6-diyl)diphenol as a tridentate ligand together with organoboronic acids or potassium trifluoroborates. The ready availability of organoboron compounds is a significant advantage of this direct photoexcitation protocol. The excited states of these borates can also serve as strong reductants, enabling various transformations.
- Miyamoto, Yusuke,Sumida, Yuto,Ohmiya, Hirohisa
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supporting information
p. 5865 - 5870
(2021/07/31)
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- Generation of Alkyl Radical through Direct Excitation of Boracene-Based Alkylborate
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The generation of tertiary, secondary, and primary alkyl radicals has been achieved by the direct visible-light excitation of a boracene-based alkylborate. This system is based on the photophysical properties of the organoboron molecule. The protocol is applicable to decyanoalkylation, Giese addition, and nickel-catalyzed carbon-carbon bond formations such as alkyl-aryl cross-coupling or vicinal alkylarylation of alkenes, enabling the introduction of various C(sp3) fragments to organic molecules.
- Hashizume, Daisuke,Hosoya, Takamitsu,Nakamura, Kei,Ohmiya, Hirohisa,Sato, Yukiya,Sumida, Yuto
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supporting information
p. 9938 - 9943
(2020/06/27)
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- Electrochemical Deoxygenation of N-Heteroaromatic N -Oxides
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An electrochemical method for the deoxygenation of N-heteroaromatic N -oxide to give the corresponding N-heteroaromatics has been developed. Several classes of N-heterocycles such as pyridine, quinoline, isoquinoline, and phenanthridine are tolerated. The electrochemical reactions proceed efficiently in aqueous solution without the need for transition-metal catalysts and waste-generating reducing reagents.
- Xu, H.-C.,Xu, P.
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supporting information
p. 1219 - 1221
(2019/06/08)
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- Lewis Acid-Catalyzed Selective Reductive Decarboxylative Pyridylation of N-Hydroxyphthalimide Esters: Synthesis of Congested Pyridine-Substituted Quaternary Carbons
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A practical and efficient Lewis acid-catalyzed radical-radical coupling reaction of N-hydroxyphthalimide esters and 4-cyanopyridines with inexpensive bis(pinacolato)diboron as reductant has been developed. With ZnCl2 as the catalyst, a wide range of quaternary 4-substituted pyridines, including highly congested diarylmethyl and triarylmethyl substituents, could be selectively obtained in moderate to good yields with broad functional group tolerance. Combined theoretical calculations and experimental studies indicate that the Lewis acid could coordinate with the cyano group of the pyridine-boryl radical to lower the activation barrier of the C-C coupling pathway, leading to the formation of 4-substituted pyridines. Moreover, it could also facilitate the decyanation/aromatization of the radical-radical coupling intermediate.
- Gao, Liuzhou,Wang, Guoqiang,Cao, Jia,Chen, Hui,Gu, Yuming,Liu, Xueting,Cheng, Xu,Ma, Jing,Li, Shuhua
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p. 10142 - 10151
(2019/10/16)
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- Regioselective and Transition-Metal-Free Addition of tert -Butyl Magnesium Reagents to Pyridine Derivatives: A Convenient Method for the Synthesis of 3-Substituted 4- tert -Butylpyridine Derivatives
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A variety of 3,4-disubstituted pyridine derivatives with a tert -butyl group in the 4-position were synthesized in a transition-metal-free, two-step reaction sequence from 3-substituted pyridine precursors. Highly regioselective addition of t -Bu 2 Mg to TIPS-activated pyridines and an efficient microwave-assisted aromatization with sulfur as oxidant afforded the desired 3,4-disubstituted pyridine derivatives in moderate to excellent yields. The method is compatible with many functional groups such as ester, amide, halide, nitrile or alkyne groups present in the 3-position.
- Rappenglück, Sebastian,Niessen, Karin V.,Seeger, Thomas,Worek, Franz,Thiermann, Horst,Wanner, Klaus T.
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p. 4055 - 4064
(2017/08/29)
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- Structures, Lewis Acidities, Electrophilicities, and Protecting Group Abilities of Phenylfluorenylium and Tritylium Ions
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The isolation, characterization, and the first X-ray structures of a fluorenylium ion and its Lewis adducts with nitrogen- and phosphorus-centered Lewis bases are reported. Kinetics of the reactions of a series of fluorenylium ions with reference π-, σ-, and n-nucleophiles of various sizes and nucleophilicities allowed the interplay between electronic and structural parameters on the electrophilicities of these planarized tertiary carbenium ions to be elucidated. Structure–reactivity correlations and extensive comparisons of their reactivities with those of di- and triarylcarbenium ions are described. Quantitative determination of the electrofugalities of fluorenylium ions revealed to which extent they are complementing tritylium ions as protecting groups and how their tuning is possible. Determination of the equilibrium constants of the Lewis adducts formation between pyridines of calibrated Lewis basicities and phenylfluorenylium and tritylium ions allowed the determination of their Lewis acidities and to showcase the potential of these carbon-centered Lewis acids in catalysis.
- Follet, Elsa,Mayer, Peter,Berionni, Guillaume
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supporting information
p. 623 - 630
(2017/01/18)
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- Synthesis and utility of dihydropyridine boronic esters
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When activated by an acylating agent, pyridine boronic esters react with organometallic reagents to form a dihydropyridine boronic ester. This intermediate allows access to a number of valuable substituted pyridine, dihydropyridine, and piperidine products.
- Panda, Santanu,Coffin, Aaron,Nguyen, Q. Nhu,Tantillo, Dean J.,Ready, Joseph M.
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supporting information
p. 2205 - 2209
(2016/02/18)
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- Dynamic Covalent Chemistry of Nucleophilic Substitution Component Exchange of Quaternary Ammonium Salts
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Dynamic covalent libraries (DCLs) of quaternary ammonium cations were set up by reversible nucleophilic substitution (SN2′ and SN2) exchange reactions of ammonium salts and tertiary amines. The reactions were conducted at 60 °C to generate thermodynamically and kinetically controlled mixtures of quaternary ammonium compounds and tertiary amines, and were accelerated by using iodide as a nucleophilic catalyst. Microwave irradiation was used to assist the exchange reaction between the pyridinium salts and pyridine derivatives. Finally, experiments towards the generation of dynamic ionic liquids were performed. The results of this study pave the way for the extension of dynamic combinatorial chemistry to nucleophilic substitution reactions.
- Kulchat, Sirinan,Lehn, Jean-Marie
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p. 2484 - 2496
(2015/11/02)
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- Mild and efficient deoxygenation of amine-N-oxides with BiCl3/Indium system
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The BiCl3/indium system was found to be a new reagent for deoxygenation of various amine-N-oxides to the corresponding amines in good to excellent yields under mild conditions.
- Yoo, Byung Woo,Choi, Jin Woo
-
experimental part
p. 3550 - 3554
(2009/12/03)
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- Mild and efficient deoxygenation of amine-N-oxides with MoCl5/NaI system
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The MoCl5/NaI system was found to be a new reagent for deoxygenation of various amine-N-oxides to the corresponding amines in good to excellent yields under mild conditions. Copyright Taylor & Francis Group, LLC.
- Yoo, Byung Woo,Park, Min Chol
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p. 1646 - 1650
(2008/09/20)
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- Deoxygenation of pyridine N-oxides with dimethylthiocarbamoyl chloride
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(Chemical Equation Presented) Treatment of pyridine N-oxides with dimethylthiocarbamoyl chloride in boiling acetonitrile effects chemoselective deoxygenation to pyridines.
- Ponaras, Anthony A.,Zaim, Oemer
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p. 487 - 489
(2008/03/29)
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- Facile deoxygenation of amine-N-oxides with CoCl2·6H 2O-indium system
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CoCl2·6H2O/In system was found to be a new reagent for deoxygenation of various amine-N-oxides to the corresponding amines in good to excellent yields under sonication. Copyright Taylor & Francis Group, LLC.
- Jung, Hwa Han,Kyung, Il Choi,Joong, Hyup Kim,Cheol, Min Yoon,Byung, Woo Yoo
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p. 415 - 419
(2007/10/03)
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- Mild and Efficient Deoxygenation of Amine-N-oxides with Titanium Tetrachloride-Indium System
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TiCl4/In system was found to be a new reagent for deoxygenation of various amine-N-oxides to the corresponding amines in good to excellent yields under mild conditions.
- Yoo, Byung Woo,Choi, Kwang Hyun,Choi, Kyung Il,Kim, Joong Hyup
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p. 4185 - 4189
(2007/10/03)
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- An Efficient Deoxgenation of Heteroaromatic N-Oxides Using Zinc Dust/Ammonium Formate Reagent System
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Heteroaromatic N-oxides were readily and selectively deoxygenated to the corresponding bases with zinc/ammonium formate reagent system.
- Balicki, Roman,Cybulski, Marcin,Maciejewski, Grzegorz
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p. 4137 - 4141
(2007/10/03)
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- A mild and selective deoxygenation of N-oxides with ammonium formate as a catalytic hydrogen transfer agent
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Ammonium formate catalytic transfer hydrogenation in the presence of raney nickel has shown utility for mild and selective deoxygenation of heteroaromatic N-oxides in neutral medium.
- Balicki, Roman,Maciejewski, Grzegorz
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p. 1681 - 1683
(2007/10/03)
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- A mild deoxygenation of heteroaromatic N-oxides by formamidinesulfinic acid
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Various heteroaromatic N-oxides were efficiently deoxygenated to the corresponding bases under mild conditions using formamidinesulfinic acid (thiourea S,S-dioxide).
- Balicki, Roman,Chmielowiec, Urszula
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p. 1105 - 1107
(2007/10/03)
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- Chiral phosphorus(III) triflates. On the nature of the phosphorus-oxygen interaction
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Reaction of chiral phosphorodiamidites with trimethylsilyltriflate affords chiral phophorus(III) triflate species, such as 1-trifluoromethylsulfonato-2,9-(dibenzyl)diaza-1-phospha[4.0.3]bicyclononane 4, which has been examined by a combination of solution and solid state analytical techniques. Arguably the most important feature of this molecule is the nature of the interaction between phosphorus and triflate oxygen atoms. Single crystal X-ray diffraction analysis reveals that the phosphorus atom interacts principally with two oxygen atoms from two different triflate groups in the solid state, implying overall four-coordination at phosphorus. At distances of 2.841 and 2.755 A, these interactions are well within the van der Waals distance for a phosphorus-oxygen [P-O] interaction (ca. 3.35 A) but are nevertheless over 1 A longer than expected for a single [P-O] covalent bond. Investigations in solution via a combination of 31P, 19F, 13C, variable concentration, variable temperature NMR spectroscopy and solution conductivity provide support for a phosphorus-oxygen interaction which is intermediate between 'ionic' (two-coordinate phosphorus) and 'covalent' (three-coordinate phosphorus) and which possesses dynamic character in solution. Indeed, it has proved possible to calculate a relative equilibrium constant between 'ionic' and 'covalent' forms of 4 using empirical NMR data (13C and 19F; CH2Cl2 solvent; 300 K). These calculations return an equilibrium constant of ca. 3 (2.8 using 13C-NMR data and 3.3 using 19F-NMR data) in favour of the ionic form, a result commensurate with those suggested from variable temperature 19F-NMR and solution conductivity studies. Indeed, that the triflate group in 4 is capable of being displaced readily has been demonstrated by reaction with two-electron nitrogen, oxygen and phosphorus donor molecules. We have found 13C{1H}-NMR spectroscopy to be an extremely valuable probe of the ionic character of the triflate group in such systems providing a quantitative measure of the relative strength of interaction (relative basicity Br) between donor molecule and phosphorus atom of 4; the stronger the interaction, the more ionic the character of the triflate group and the lower the value of Br. Indeed, Br values for various ligands correlate well with steric and electronic properties of the latter and 31P-NMR resonances of the adducts themselves. As expected, the relative basicity of a given ligand correlates to the equilibrium constants K for adduct formation, which range from 39 M-1 for the weakest binding ligand studied (1,4-dioxane) to 5.4×104 M-1 for the strongest binding ligand (4-Me2N-NC5H4).
- Jones, Victoria A.,Sriprang, Sarin,Thornton-Pett, Mark,Kee, Terence P.
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p. 199 - 218
(2007/10/03)
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- tert-Butylation of Quinolinium Cations and Quinoline N-Oxides by tert-Butylmercury Halides
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In the presence of t-BuHgCl/KI the radical cations formed by the addition of tert-butyl radicals to C-2 of the quinolinium cation react in Me2SO by proton loss followed by one-electron oxidation (1a, R=H, Me, Cl).For the N-methyl, or N-methoxyquinolinium cations proton loss is not observed and the radical cations react by one-electron reduction (1b, R=Me, Cl; 1c, R=Me).With quinoline N-oxide and its 4-substituted derivatives the C-2 adduct radicals (1d, R=H, Me, Cl) are deprotonated by DABCO to yield after one-electron oxidation the 2-tert-butylquinoline N-oxides.The adduct radical cations formed by t-Bu. addition at the C-4 quinolinium ions 2 seldom lose the C-4 proton but react by reduction, hydration, or in the case of 2-chloroquinoline N-oxide, dimerization.The loss of the proton from the 2-adducts 1 but not from the 4-adducts 2 seems to be stereoelectronic in origin.With N-methylquinolinium cation the addition of t-Bu. occurs selectively (>90percent) at C-4 in contrast to the low selectivity observed in addition to quinolinium ion itself.However, with N-methoxyquinolinium perchlorate the major reaction products (70-90percent) result from the addition of t-Bu. at C-2.
- Russell, Glen A.,Wang, Lijuan,Yao, Ching-Fa
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p. 5390 - 5395
(2007/10/02)
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- SIMPLE AND CONVENIENT DEOXYGENATION OF HETEROAROMATIC N-OXIDES WITH SODIUM HYPOPHOSPHITE
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Sodium hypophosphite catalytic transfer hydrogenation in the presence of 10percent palladium on carbon constitutes a simple and excellent deoxygenation method for heteroaromatic N-oxides in acetic acid medium.
- Balicki, Roman,Kaczmarek, Lukasz
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p. 385 - 386
(2007/10/02)
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- tert-butylation of pyridines, quinolines, and isoquinolines by tert-butylmercury halides
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Photolysis of tert-butylmercury halides with pyridinium or quinolinium salts leads to alkylation via the intermediacy of adduct radical cations. With simple pyridines or the 2-adducts from quinolines, the radical cations readily lose a proton to form a substituted pyridinyl radical which is easily oxidized by the alkylmercury halide. Addition of t-Bu? at the 4-position of the quinolinium ions, the 1-position of the isoquinolinium ions, or the 9-position of the acridinium ions, yields in the presence of KI the dihydro derivatives formed via electron transfer to the adduct '? radical cation from I- or its ate-complex with the tert-butylmercury halide. A similar reductive alkylation is observed for the radical cations formed by the addition of t-Bu? to the β-position of the 4-vinylpyridinium ion or to the N-methylated cations derived from pyridine-3,4-dicarboximide, acridine, quinaldine, or isoquinoline. Competition between substitutive (oxidative) and additive (reductive) alkylation reflects the ease of proton loss from the intermediate adduct radical cation. Because of reversibility in adduct formation and variable rates of deprotonation of the adducts, yields of substitutive alkylation products are often not a true measure of the selectivity in the initial radical addition step. 4-tert-Butyl-1,4-dihydro-2-methylquinoline can be isolated from the photolysis of quinaldine with t-BuHgCl in the presence of KI/PTSA, methylated at C-3 by methyl iodide during the tert-butylation reaction, reduced by NaBH4 upon workup, or oxidized to the quinoline at long reaction times. 4-tert-Butyl-1,4-dihydroquinoline reacts rapidly in the presence of PTSA and t-BuHgCl to form 2,4-di-tert-butyl-1,2,3,4-tetrahydroquinoline while 4-/er/-butyl-2-chloro1,4-dihydroquinoline is readily hydrolyzed to form the amide. Although 1 -tert-butyl-1,2-dihydro-3-methylisoquinoline is isolable, 1 -tert-butyl-1,2-dihydroisoquinoline reacts via the iminium ion to form 1,3-di-tert-butyltetrahydroisoquinoline and the de-tert-butylated product 3-tert-butyl-3,4-dihydroisoquinoline. De-tert-butylation with aromatization is also observed upon photolysis of 4-tert-butyl-3,4-dihydro-2,3-dimethylquinoline with t-BuHgCl.
- Russell, Glen A.,Rajaratnam, Rajine,Wang, Lijuan,Shi, Bing Zhi,Kim, Byeong Hyu,Yao, Ching Fa
-
p. 10596 - 10604
(2007/10/02)
-
- Pentacyanoferrates(II): Solvatochromism and Reactivity in Micelles and in Reversed Micelles
-
Rate constants for dissociation of pyridine derivatives from pentacyanoferrates(II), (3-), in micelles and in reversed micelles reflect significant interactions between the leaving ligands and the micelle or the water in the interior of the
- Burgess, John,Patei, Marttand S.
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p. 783 - 788
(2007/10/02)
-
- Mechanism of the Grignard Addition Reaction. XV. The Reaction of Grignard Reagents with Benzylpyridinium Chloride
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The reaction of Grignard reagents with benzylpyridinium chloride produces 2-alkyl-N-benzyl-1,2- and 4-alkyl-N-benzyl-1,4-dihydropyridines.The mechanism seems to be polar, concerted except for the t-butylmagnesium reagent.The adducts may reduce the starting material to the unreported, non-alkylated N-benzyl-1,4-dihydropyridine.If the Grignard-alkyl is secondary, crystalline 4-alkylidene-1,4-dihydropyridines may be produced.Thermal rearrangements of N-benzyl-1,4-dihydropyridines lead to migration of the benzyl group.
- Holm, Torkil
-
p. 276 - 279
(2007/10/02)
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- TiCl4/NaI - A Novel, Efficient Reagent for Mild Reduction of the N-O Bond in Amine N-Oxides and Nitrones
-
Heteroaromatic N-oxides and nitrones were readily and selectively deoxygenated to the corresponding bases or imines in excellent yields with the TiCl4/NaI reagent system.
- Balicki, Roman
-
p. 647 - 649
(2007/10/02)
-
- Efficient Deoxygenation of Heteroaromatic N-Oxides with Ammonium Formate as a Catalytic Hydrogen Transfer Agent
-
Ammonium formate catalytic transfer hydrogenation in the presence of 10percent palladium on carbon has shown utility for mild and excellent deoxygenation of heteroaromatic N-oxides in neutral medium.
- Balicki, Roman
-
p. 645 - 646
(2007/10/02)
-
- SIMPLE AND EFFICIENT DEOXYGENATION OF HETEROAROMATIC N-OXIDES USING TiCl4/SnCl2.
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Various unfunctionalized heteroaromatic N-oxides are efficiently deoxygenated to the corresponding bases under mild conditions by treatment with the novel reagent TiCl4/SnCl2.
- Kaczmarek, Lukasz,Malinowski, Marek,Balicki, Roman
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p. 787 - 790
(2007/10/02)
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- Carbon-Skeletal Anionic and Radical Sigmatropic Rearrangements: Group Migratory Aptitudes as a Probe of Charge Type in the 1,2-Shifts of β-Phenyl-β-(2-pyridyl)- and β-Phenyl-β-(4-pyridyl)ethyl Systems
-
In order to probe the occurrence and relative ease of carbon-skeletal sigmatropic rearrangements of the free-radical, anionic, or radical-anionic type, derivatives of the β,β-diphenyl-β-(2-pyridyl)- and the β,β-diphenyl-β-(4-pyridyl)ethane systems, PyPh2CCH2E (A), were treated with reagents expected to generate radical or anionic sites.The ensuing, competitive -shifts of the phenyl and/or pyridyl groups were then used as a diagnostic sign of the mechanism of rearrangement.Both the treatment of A (E = p-tolyl) with MeLi or KH and the reaction of A (E = Cl) with sodium or lithium in donor solvents caused an exclusive -pyridyl shift.Gas chromatographic and mass spectral analyses were able to place the limit of any -phenyl shift as under 0.5percent.In such alkali metal reactions, persistent aromatic radical-anions were detected by ESR spectroscopy until the completion of the reaction.Such signals and the significant amounts of carbon-carbon bond cleavage products support the formation of pyridyl radical-anions as precursors for such cleavages and -pyridyl rearrangements.That such radical-anions could lead to spiro intermediates that promote the -pyridyl migrations wins corroboration from the finding that the methiodide of 1-chloro-2-methyl-2-(4-pyridyl)propane can be reduced with lithium in THF to yield the isolable 1,1,6-trimethyl-6-azaspiroocta-4,7-diene.The same two chlorides of A responded differently under other rearrangement conditions: (1) in preparing such chlorides from the corresponding alcohols, PyPh2CCH2OH, with thionyl chloride, the 4-pyridyl isomer underwent a Wagner-Meerwein rearrangement with exclusive -phenyl migration; the 2 isomer underwent normal displacement of OH by Cl; (2) toward the free-radical reducing agent, (n-Bu)3SnH, the 2-chloro isomer underwent both -phenyl and -pyridyl shifts, while the 4-chloro isomer underwent neither reduction nor rearrangement; it simply induced the formation of hexa-n-butylditin.A similar reducing action was observed with bis(1,5-cyclooctadiene)nickel.These observations are analyzed with the aid of Hueckel molecular orbital theory and the rearrangements observed with reducing agents are assessed in terms of three types of mechanisms: (1) authentic -anionic shifts; (2) authentic -free-radical shifts; and (3) competing electron transfer from the metal to the chloride center or from the metal to the pyridyl ring, which permits anionic rearrangements to compete with rearrangements mediated by radical-anion or dianions, which latter processes form the crucial spiro intermediate by intramolecular nucleophilic displacement on the CH2Cl group.
- Eisch, John J.,Kovacs, Csaba A.,Chobe, Prabodh,Boleslawski, Marek P.
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p. 4427 - 4437
(2007/10/02)
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- Alkylation of Pyridine in Free Radical Chain Reactions Utilizing Alkylmercurials
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Pyridines or N,N,N',N'-tetramethyl-p-phenylenediamine will undergo a photostimulated free radical chain reaction with alkylmercury halides or carboxylates, yielding ring alkylated substitution products.Alkene mercuration products (R1CH(Y)CH(R2)HgX with Y=HO, RO, CH3CONH; X=Cl, CH3CO2, CF3CO2) can be used without isolation for the alkylation reaction
- Russell, Glen A.,Guo, Deliang,Khanna, Rajive K.
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p. 3423 - 3425
(2007/10/02)
-
- Synthetic Applications of N-N Linked Heterocycles. Part 13. N-(2,5-Dimethylpyrrol-1-yl)pyridinium Salts in the Synthesis of 4-Alkyl and 4-Aryl-pyridines via Regiospecific Attack of Grignard Reagents and Organolithium Compounds.
-
The reaction between N-(2,5-dimethylpyrrol-1-yl)pyridinium salts and alkyl- or aryl-Grignard reagents, or organolithium compounds, gives regiospecifically 1,4-dihydro-intermediates.These may be isolated and decomposed under free-radical conditions to give moderate to good yields of 4-alkyl- and 4-aryl-pyridines.Results are compared with those obtained from a related reaction sequence involving N-(2,6-dimethyl-4-oxopyridin-1-yl)pyridinium salts.
- Katritzky, Alan R.,Beltrami, Hector,Sammes, Michael P.
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p. 1684 - 1696
(2007/10/02)
-
- Method of regulating the growth of aquatic weeds with pyridine derivatives
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A method of regulating the growth of submerged and floating aquatic weeds which comprises adding a 2- or 4-substituted pyridinemethane or pyridinemethanol to a body of water containing the submerged and floating aquatic weeds to be regulated, in quantities sufficient to regulate the growth of the submerged and floating aquatic weeds therein. The disclosure also relates to novel compositions for carrying out the method.
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