- Catalytic reduction of an α,β-disubstituted alkene with sodium borohydride in the presence of tetra-tert-butylphthalocyanine complexes
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Cobalt tetra-tert-butylphthalocyanine was found an efficient catalyst for the catalytic reduction of 4-[(E)-2-phenylethenyl]-pyridine to 4-(2-phenylethyl)pyridine with sodium borohydride.
- Kalashnikov, Valery V.,Tomilova, Larisa G.
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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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- Iridium-Catalyzed C-Alkylation of Methyl Group on N-Heteroaromatic Compounds using Alcohols
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In this study, we developed a catalytic system for the C-alkylation of a methyl group on N-heteroaromatic compounds, including pyridine, pyrimidine, pyrazine, quinoline, quinoxaline, and isoquinoline, using alcohols based on a hydrogen-borrowing process with [Cp*IrCl2]2 (Cp*: η5-pentamethylcyclopentadienyl) combined with potassium t-butoxide and 18-crown-6-ether as the catalyst precursor.
- Onoda, Mitsuki,Fujita, Ken-Ichi
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supporting information
p. 7295 - 7299
(2020/10/02)
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- Chemoselective Hydrogenation of Alkynes to (Z) -Alkenes Using an Air-Stable Base Metal Catalyst
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A highly selective hydrogenation of alkynes using an air-stable and readily available manganese catalyst has been achieved. The reaction proceeds under mild reaction conditions and tolerates various functional groups, resulting in (Z)-alkenes and allylic alcohols in high yields. Mechanistic experiments suggest that the reaction proceeds via a bifunctional activation involving metal-ligand cooperativity.
- Zubar, Viktoriia,Sklyaruk, Jan,Brzozowska, Aleksandra,Rueping, Magnus
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supporting information
p. 5423 - 5428
(2020/07/24)
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- A Bidentate Ru(II)-NC Complex as a Catalyst for Semihydrogenation of Alkynes to (E)-Alkenes with Ethanol
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Four Ru(II)-NC complexes were tested as catalysts for semihydrogenation of internal alkynes to (E)-alkenes with ethanol, and the complex {(C5H4N)(C6H4)}RuCl(CO)(PPh3)2 (1a) showed the highest activity. The reactions proceeded well with 1 mol % catalyst loading and 0.1 equiv of t-BuONa at 110 °C for 1 h, and 32 alkenes were synthesized with excellent E:Z selectivity. This is the first ruthenium-catalyzed semihydrogenation of internal alkynes to (E)-alkenes using ethanol as the hydrogen donor.
- Chen, Dafa,Gong, Dawei,Hu, Bowen,Kong, Degong,Xia, Haiping,Yang, Weiwei
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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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- Ni-catalyzed Reductive Deaminative Arylation at sp3 Carbon Centers
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A Ni-catalyzed reductive deaminative arylation at unactivated sp3 carbon centers is described. This operationally simple and user-friendly protocol exhibits excellent chemoselectivity profile and broad substrate scope, thus complementing existing metal-catalyzed cross-coupling reactions to forge sp3 C-C linkages. These virtues have been assessed in the context of late-stage functionalization, hence providing a strategic advantage to reliably generate structure diversity with amine-containing drugs.
- Martin-Montero, Raul,Yatham, Veera Reddy,Yin, Hongfei,Davies, Jacob,Martin, Ruben
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p. 2947 - 2951
(2019/04/30)
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- Semireduction of Alkynes Using Formic Acid with Reusable Pd-Catalysts
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The treatment of PdCl2 with K2CO3 and HCO2H in dioxane gives black precipitates, which are an effective catalyst for the semireduction of alkynes to alkenes using formic acid as a reductant. Even 0.05 mol % Pd promoted the reduction reaction of tolane in high yield with high selectivity.
- Iwasaki, Riku,Tanaka, Eikichi,Ichihashi, Toshinari,Idemoto, Yasushi,Endo, Kohei
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p. 13574 - 13579
(2018/11/02)
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- Ligand-Free RuCl3-Catalyzed Alkylation of Methylazaarenes with Alcohols
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RuCl3 efficiently catalyzes the alkylation of methylquinolines, methylpyridines, 2-methyl-benzooxazoles, and 2-methyl-quinoxalines with alkyl- or aryl-alcohols as alkylating agents. This synthetically useful and atom economical transformation does not require additional ligands. The mechanistic study indicated the alkylation reaction underwent a stepwise transfer hydrogenation, aldol condensation, and hydrogenation reaction pathway.
- Feng, Tong-Yu,Li, Hong-Xi,Young, David James,Lang, Jian-Ping
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p. 4113 - 4120
(2017/04/28)
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- The Use of Ureates as Activators for Samarium Diiodide
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A novel mode of SmI2 activation has been developed using ureates as reaction promoters. Several ureates formed by treatment of the corresponding ureas with n-BuLi have been shown to activate SmI2 to a substantial extent toward the reduction of 1-chlorodecane. Complexes formed from SmI2 and various ureates have been shown to be useful for the reduction of a variety of organohalides, including substrates of low reactivity such as aryl fluorides. Because of ease of synthesis and low molecular weight, the conjugate base of triethylurea (TEU-) was of primary focus. Visible spectroscopy and reactivity data are consistent with the hypothesis that the same complex is being formed when SmI2 is combined with either 2 or 4 equiv of TEU-, in spite of the greater reactivity of SmI2/4 TEU- with some alkyl halides. We propose that the active reductant is an N,O chelate formed between SmI2 and 2 equiv of TEU-.
- McDonald, Chriss E.,Ramsey, Jeremy D.,McAtee, Christopher C.,Mauck, Joseph R.,Hale, Erin M.,Cumens, Justin A.
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p. 5903 - 5914
(2016/07/23)
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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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- Reduction of 4-styrylpyridine by SmI2: An inner sphere electron tranfer case where the binding site differs from the reaction center
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In the reduction of 4-styrylpyridine by SmI2, the binding site for SmI2 differs from the reaction center. MeOH and TFE exhibit an unprecedented behavior showing a sigmoidic effect on the reaction rate, which levels off around 0.5-1 M. The reactions display autocatalytic behavior and a U shape dependence of the reaction rate on the HMPA concentration. With high likelihood, the reactions involve a proton coupled electron transfer step.
- Yella, Ramesh,Hoz, Shmaryahu
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p. 5262 - 5265
(2013/11/06)
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- SUBSTITUTED PYRIDINE DERIVATIVES AS FABI INHIBITORS
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The present invention provides substituted pyridine derivatives of formula (I), which may be therapeutically useful as as anti-bacterial agents, more particulalrly FabI inhibitors. Formula(I) in which R1 to R5 and L have the meanings given in the specification, and pharmaceutically acceptable salts thereof that are useful in the treatment and prevention in diseases or disorder, in particular their use in diseases or disorder where there is an advantage anti-bacterial agents, more particularly FabI inhibitors. The present invention also provides methods for synthesizing and administering the FabI inhibitor compounds. The present invention also provides pharmaceutical formulations comprising at least one of the FabI inhibitor compounds together with a pharmaceutically acceptable carrier, diluent or excipient therefor.
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Page/Page column 88
(2013/06/27)
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- Scope and limitations of the Minisci reaction for the synthesis of aza-heterocycles
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Attempts to prepare several classes of aza-heterocycles by application of the Minisci radical cyclisation reaction are described. Competing β-scission, hydrolytic cleavage and lactonisation reactions were found to be major hurdles to adopting this strategy for the synthesis of such targets.
- Burgin, Ryan N.,Jones, Simon,Tarbit
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scheme or table
p. 6772 - 6774
(2010/04/27)
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- New functionalised silicas for highly selective cation exchange SPE purification in medicinal chemistry
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Functionalised silicas 2 and 3 are effective for the cation exchange SPE purification of basic molecules containing acid-sensitive functionalities, the selective separations of mixtures of basic compounds and accelerated reaction work-ups/product isolatio
- Brown, Jane,Chighine, Alessandra,Colucci, Marie A.,Galaffu, Nicola,Hirst, Simon C.,Seymour, Helen M.,Shiers, Jason J.,Wilkes, Robin D.,Williams, Jonathan G.,Wilson, John R.H.
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p. 4968 - 4971
(2008/09/21)
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- Reductive metalation of 1,2-diaryl-substituted ethenes: Synthetic applications
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Reduction of 1,2-diaryl-substituted ethenes with Na metal in dry THF allowed easy access to a variety of 1,2-diaryl-1,2-disodiumethanes. These diorganometallic intermediates were elaborated into the corresponding 1,2-diarylethanes (aqueous work up), or cycloalkylated with 1,3- dichloropropanes. The last reaction led to a highly diastereoselective synthesis of trans-1,2-diaryl-substituted cyclopentanes.
- Azzena, Ugo,Dettori, Giovanna,Lubinu, Caterina,Mannu, Alberto,Pisano, Luisa
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p. 8663 - 8668
(2007/10/03)
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- Synthesis, photophysical, photochemical and electrochemical properties of rhenium(I) diimine complexes with photoisomerizable pyridyl-azo, -ethenyl or -ethyl ligands
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A series of rhenium(I) diimine complexes with pyridyl-azo, -ethenyl or -ethyl type ligands, [Re(CO)3(N-N)L]ClO4 and [{Re(CO)3(N-N)}2L′][ClO4]2 {N-N = 2,2′-bipyridine (bpy), 1,10-phenanthroline (phen); L = 4-phenylazopyridine (PHAZO), 4-styrylpyridine (STYPY), [2-(4-pyridyl)ethyl]benzene (PEB), 4-(4-nitrostyryl)pyridine (NSP); L′ = 4,4′-azopyridine (AZO), 1,4-bis[2-(4-pyridyl)ethenyl]benzene (BPENB), 1,4-bis[2-(4-pyridyl)ethyl]benzene (BPEB)} have been synthesized and their photophysical properties studied. The quantum yields for the photoinduced isomerization of the complexes [Re(CO)3(bpy)(NSP)]+ and [Re(CO)3(phen)(NSP)]+ have been determined.
- Yam, Vivian Wing-Wah,Lau, Victor Chor-Yue,Wu, Li-Xin
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p. 1461 - 1468
(2007/10/03)
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- Study of radical merostabilization of electrospray FTICR/MS
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The threshold fragmentation energies (E(o)) of three different 4-(1'-substituted-2'-phenethyl)-1-methylpyridinium salts containing a neutral, an electron-donor, or an electron-acceptor group as α-substituent, respectively, were measured by Fourier Transfo
- Katritzky, Alan R.,Shipkova, Petia A.,Qi, Ming,Nichols, Daniel A.,Burton, Richard D.,Watson, Clifford H.,Eyler, John R.,Tamm, Toomas,Karelson, Mati,Zerner, Michael C.
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p. 11905 - 11911
(2007/10/03)
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- Vicarious nucleophilic substitution of pyridines and 1,2,3-triazines via their dicyanomethylide derivatives
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Vicarious nucleophilic substitution using chloromethyl phenyl sulfone was applied to pyridinium and 1,2,3-triazinium dicyanomethylides to afford corresponding 4-substituted pyridinium and 5-substituted triazinium dicyanomethylides, respectively. They were
- Nagata,Itoh,Okada,Ohsawa
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p. 1644 - 1648
(2007/10/02)
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- Flexible N-methyl-4-phenyl-1,2,3,6-tetrahydropyridine analogues: Synthesis and monoamine oxidase catalyzed bioactivation
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Eighteen analogues of N-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) were synthesized and evaluated as substrates of monoamine oxidase. In general, the flexible analogues, characterized by the presence of a methylene (or ethylene) bridge between the aryl/heteroaryl and tetrahydropyridyl moieties, were better substrates of the enzyme than the conformationally restricted MPTP. It is suggested that the increased oxidative activity of these flexible analogues reflects enhanced binding due to the ability of the C-4-aryl/heteroaryl substituent to gain access to a hydrophobic pocket within the substrate binding site.
- Efange,Michelson,Remmel,Boudreau,Dutta,Freshler
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p. 3133 - 3138
(2007/10/02)
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- Intramolecular aromatic alkylation. 28. Synthesis and pharmacological testing of homologized and hydroxylated 3,4-dihydro-1'-methylspiro[naphthalin-1(2H),4'-piperidine
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The compounds 4, 8, and 10, prepared by standard methods, are converted to the phenylpyridylakanes 9; their methoiodides 11 are reduced to yield the tetrahydropyridines 12. Whereas the cyclisation of 12a gives the isomers 1f and 1g, 12b furnishes only the
- Reimann,Speckbacher,Schuenemann
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- PHOTOCHEMICAL GENERATION OF ALIPHATIC RADICALS FROM BENZOPHENONE OXIME ESTERS: SIMPLE SYNTHESIS OF ALKYLBENZENES AND ALKYLPYRIDINES
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Photolysis of benzophenone oxime esters, prepared with aliphatic carboxylic acids and benzophenone oxime, in benzene and pyridine generates various primary, secondary and tertiary aliphatic radicals selectively, and corresponding alkylbenzenes and alkylpyridines are produced in good yields, respectively.
- Hasebe, Masato,Tsuchiya, Takashi
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p. 3239 - 3242
(2007/10/02)
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- A Convenient Method for the Regioselective Synthesis of 4-Alkyl(aryl)pyridines Using Pyridinium Salts
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RCu.BF3 reacted with 1-ethocycarbonylpyridinium chloride at the 4-position with almost complete regioselectivity (>99percent) to afford the corresponding 1,4-dihydropyridine derivatives in high yields (81-94percent).The dihydropyridines were oxidized by oxygen to give 4-alkyl(aryl)pyridines (38-68percent).Grignard reagents also reacted with 1-t-butyldimethylsilylpyridinium triflate with almost complete regioselectivity (>99percent) to afford the corresponding 1,4-dihydropyridines, which were easily oxidized to give 4-substituted pyridines in higher yields than above (58-70percent).
- Akiba, Kin-ya,Iseki, Yuji,Wada, Makoto
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p. 1994 - 1999
(2007/10/02)
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- Electrochemical Adamantylation of Styrylpyridines
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The reaction between electrochemically generated anion radicals of the 4-(4-styryl)-pyridines 1-6 and 1-bromoadamantane gives, in solvents of low proton availability as N,N-dimethylformamide via an electron transfer in solution and formation of 1-adamantyl-radicals, monoadamantylated pyrid-4-yl-phenylethanes.The major product results from an anion radical/radical-coupling in the 2(β)-next the 1(α)-position.A competing pathway of the electrohydroadamantylation is the hydrogeneration of the -CH=CH-double bond, whose importance increases with the water content of the solvent.Based on cyclic-voltammetric evidence and product distribution, the mechanism of the reductive coupling of 1-6 in the presence of 1-bromoadamantane is discussed in terms of indirect electrolysis.
- Hess, U.,Huhn, D.
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p. 301 - 308
(2007/10/02)
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- REGIOSELECTIVE SYNTHESIS OF 4-ALKYLPYRIDINES VIA 1,4-DIHYDROPYRIDINE DERIVATIVES FROM PYRIDINE
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N-Ethoxycarbonylpyridinium chloride (1) reacted with at 4-position with almost complete regioselectivity (better than 99percent) to afford the corresponding 1,4-dihydropyridine derivatives (2) in high yields (81 ca. 94percent).The dihydropyridines were readily oxidized by oxygen to give 4-alkylpyridines (4:38 ca. 68percent yields).
- Akiba, Kin-ya,Iseki, Yuji,Wada, Makoto
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p. 429 - 432
(2007/10/02)
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- FACILE SYNTHESIS OF 4-SUBSTITUTED PYRIDINES USING GRIGNARD REAGENTS
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N-t-Butyldimethylsilylpyridinium triflate (2) reacted with Grignard reagents at 4-position with almost complete regioselectivity (99percent) to afford the corresponding 1,4-dihydropyridine derivatives (3), which are easily oxidized by oxygen to give 4-substituted pyridines (4: 58-70percent).
- Akiba, Kin-ya,Iseki, Yuji,Wada, Makoto
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p. 3935 - 3936
(2007/10/02)
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- FLUORIDE ION INDUCED REACTIONS OF ORGANOSILANES WITH ELECTROPHILES
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Benzyl- 4-picolyl- and phenylallyl(trimethyl)silanes react with electrophiles in the presence of KF/18-crown-6 or silica-TBAF under mild conditions.
- Ricci, Alfredo,Degl'Innocenti, Alessandro,Fiorenza, Mariella,Taddei, Maurizio,Spartera, Maria A.,Walton, David R.M.
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p. 577 - 578
(2007/10/02)
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- 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.
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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)
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