- X-ray spectroscopic verification of the active species in iron-catalyzed cross-coupling reactions
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X-ray absorption: The activation of the pre-catalyst as well as the catalytically active species and reaction mechanism of Fe-catalyzed cross-couplings were investigated by X-ray absorption spectroscopy. The active catalytic components are small iron clus
- Schoch, Roland,Desens, Willi,Werner, Thomas,Bauer, Matthias
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- Odd-Even Effect on the Spin-Crossover Temperature in Iron(II) Complex Series Involving an Alkylated or Acyloxylated Tripodal Ligand
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In the context of magneto-structural study, a relatively short alkyl group was introduced to anionic spin-crossover (SCO) building blocks based on [Fe(py3CR)(NCS)3]-, where py3CR stands for tris(2-pyridyl)methyl derivatives. The linear alkyl and acyloxyl derivatives of Me4N[Fe(py3CR)(NCS)3] with R = CnH2n+1 (n = 1-7) and CnH2n+1CO2 (n = 1-6) were synthesized, and the magnetic study revealed that all the compounds investigated here exhibited SCO. The SCO temperature (T1/2) varied in 289-338 K for the alkylated compounds, and those of the acyloxylated ones were lower with a narrower variation width (T1/2 = 216-226 K). The crystal structures of the former with n = 3, 4, and 5 and the latter with n = 1, 4, 5, and 6 were determined, and various molecular arrangements were characterized. There is no structural evidence for a molecular fastener effect. The plots on T1/2 against n displayed a pronounced odd-even effect; the SCO temperatures of the homologues with even n are relatively higher than those of the homologues with odd n. The odd-even effect on T1/2 may be related with the entropy difference across the SCO, rather than crystal field modification or intermolecular interaction. The present work will help molecular design to fine-tune T1/2 by means of simple chemical modification like alkylation and acyloxylation.
- Ishida, Takayuki,Kashiro, Atsushi,Kohno, Wakana
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- Stereoselective synthesis of (±)-indolizidines 167B and 209D and their trans-isomers based on the reductive allylboration of pyridine
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A general method for the synthesis of 5-substituted indolizidines based on intramolecular cyclization of trans-and cis-2-allyl-6-R-1,2,3,6-tetrahydropyridines, obtained from pyridine and triallylborane, has been elaborated. The closure of the five-membered ring is carried out by hydroboration-oxidation followed by cyclization of the resulting δ-amino alcohols in the presence of the Ph3P-CBr4-Et3N system. (Pr2BH)2 and Pr3B are used as the hydroborating reagents, and H2O2 in an acid medium is used for the oxidation of 2-[3-(dipropylboryl)propyl]-Δ3-piperideines formed. This method has been used for the synthesis of two natural alkaloids: indolizidine 209D (cis-5-hexylindolizidine) and its trans-isomer were prepared from cis-and trans-2-allyl-6-hexyl-1,2,3,6-tetrahydropiridine, respectively; indolizidine 167B and trans-5-propylindolizidine were synthesized from cis-and trans-2,6-diallyl-1,2,3,6-tetrahydropyridine, respectively.
- Bubnov,Klimkina,Ignatenko
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- Dilithium Amides as a Modular Bis-Anionic Ligand Platform for Iron-Catalyzed Cross-Coupling
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Dilithium amides have been developed as a bespoke and general ligand for iron-catalyzed Kumada-Tamao-Corriu cross-coupling reactions, their design taking inspiration from previous mechanistic and structural studies. They allow for the cross-coupling of alkyl Grignard reagents with sp2-hybridized electrophiles as well as aryl Grignard reagents with sp3-hybridized electrophiles. This represents a rare example of a single iron-catalyzed system effective across diverse coupling reactions without significant modification of the catalytic protocol, as well as remaining operationally simple.
- Neate, Peter G.N.,Zhang, Bufan,Conforti, Jessica,Brennessel, William W.,Neidig, Michael L.
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supporting information
p. 5958 - 5963
(2021/08/18)
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- Unlocking the Accessibility of Alkyl Radicals from Boronic Acids through Solvent-Assisted Organophotoredox Activation
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Despite their prevalence in organic synthesis, the application of boronic acids (BAs) as alkyl radical precursors in visible-light-assisted photocatalyzed reactions has been limited by their high oxidation potential. This study demonstrates the prominent
- Ranjan, Prabhat,Pillitteri, Serena,Coppola, Guglielmo,Oliva, Monica,Van der Eycken, Erik V.,Sharma, Upendra K.
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p. 10862 - 10870
(2021/09/08)
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- Copper-catalyzed cross-coupling of aryl-, primary alkyl-, and secondary alkylboranes with heteroaryl bromides
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A method for the Cu-catalyzed cross-coupling of both aryl and alkylboranes with aryl bromides is described. The method employs an inexpensive Cu-catalyst and functions for a variety of heterocyclic as well as electron deficient aryl bromides. In addition, aryl iodides of varying substitution patterns and electronic properties work well.
- Bergmann, Allison M.,Oldham, Adam M.,You, Wei,Brown, M. Kevin
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supporting information
p. 5381 - 5384
(2018/06/01)
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- Manganese-Catalyzed Kumada Cross-Coupling Reactions of Aliphatic Grignard Reagents with N-Heterocyclic Chlorides
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Herein we report the use of manganese(II) chloride for the catalytic generation of C(sp 2)-C(sp 3) bonds via Kumada cross-coupling. Rapid and selective formation of 2-alkylated N-heterocyclic complexes were observed in high yields with use of 3 mol% MnCl 2 THF 1.6 and under ambient reaction conditions (21 °C, 15 min to 20 h). Manganese-catalyzed cross-coupling is tolerant toward both electron-donating and electron-withdrawing functional groups in the 5-position of the pyridine ring, with the latter resulting in an increased reaction rate and a decrease in the amount of nucleophile required. The use of this biologically and environmentally benign metal salt as a catalyst for C-C bond formation highlights its potential as a catalyst for the late-stage functionalization of pharmaceutically active N-heterocyclic molecules (e.g., pyridine, pyrazine).
- Petel, Brittney E.,Purak, Merjema,Matson, Ellen M.
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supporting information
p. 1700 - 1706
(2018/07/13)
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- Ionic iron(III) complexes bearing a dialkylbenzimidazolium cation: Efficient catalysts for magnesium-mediated cross-couplings of aryl phosphates with alkyl bromides
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A series of ionic iron(III) complexes of general formula [HLn][FeX4] (HL1?=?1,3-dibenzylbenzimidazolium cation, X?=?Cl, 1; HL1, X?=?Br, 2; HL2?=?1,3-dibutylbenzimidazolium cation, X?=?Br, 3; HL3?=?1,3-bis(diphenylmethyl)benzimidazolium cation, X?=?Br, 4) were easily prepared in high yields by the direct reaction of FeX3 with 1 equiv. of [HLn]X under mild conditions. All of them were characterized using elemental analysis, Raman spectroscopy and electrospray ionization mass spectrometry, and X-ray crystallography for 1 and 4. In the presence of magnesium turnings and LiCl, these air- and moisture-insensitive complexes showed high catalytic activities in direct cross-couplings of aryl phosphates with primary and secondary alkyl bromides with broad substrate scope, wherein complex 4 was the most effective.
- Li, Zhuang,Lu, Bing,Sun, Hongmei,Shen, Qi,Zhang, Yong
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- Alkyl Grignard cross-coupling of aryl phosphates catalyzed by new, highly active ionic iron(II) complexes containing a phosphine ligand and an imidazolium cation
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A novel family of ionic iron(ii) complexes of the general formula [HL][Fe(PR′3)X3] (HL = 1,3-bis(2,6-diisopropylphenyl)imidazolium cation, HIPr, R′ = Ph, X = Cl, 2; HL = HIPr, R′ = Cy, X = Cl, 3; HL = HIPr, R′ = Ph, X = Br, 4; HL = HIPr, R′ = Cy, X = Br, 5; HL = 1,3-bis(2,4,6-trimethylphenyl)imidazolium cation, HIMes, R′ = Cy, X = Br, 6) was easily prepared via a stepwise approach in 88%-92% yields. In addition, an ionic iron(ii) complex, [HIPr][Fe(C4H8O)Cl3] (1), has been isolated from the reaction of FeCl2(THF)1.5 with one equiv. of [HIPr]Cl in 90% yield and it can further react with one equiv. of PPh3 or PCy3, affording the corresponding target iron(ii) complex 2 or 3, respectively. All these complexes were characterized by elemental analysis, electrospray ionization mass spectrometry (ESI-MS), 1H NMR spectroscopy and X-ray crystallography. These air-insensitive complexes 2-6 showed high catalytic activities in the cross-coupling of aryl phosphates with primary and secondary alkyl Grignard reagents with a broad substrate scope, wherein [HIPr][Fe(PCy3)Br3] (5) was the most effective. Complex 5 also catalyzes the reductive cross-coupling of aryl phosphates with unactivated alkyl bromides in the presence of magnesium turnings and LiCl, as well as the corresponding one-pot acylation/cross-coupling sequence under mild conditions.
- Li, Zhuang,Liu, Ling,Sun, Hong-Mei,Shen, Qi,Zhang, Yong
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p. 17739 - 17747
(2016/11/18)
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- Ionic iron (II) composition as well as preparation method and application thereof
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The invention discloses an ionic iron (II) composition as well as a preparation method and application thereof. The ionic iron (II) composition contains phosphine ligands and imidazole (quinoline) cations, and the general formula of the ionic iron (II) is [Fe(PR3)X3][(R1NCHnCHnNR1)CH], wherein X is selected from one of chlorine or bromine. The ionic iron (II) composition containing the phosphine ligands and the imidazole (quinoline) cations can efficiently catalyze a phosphoric acid aryl diethyl ester compound and an alkyl group Grignard reagent to perform a crisscross coupling reaction, and particularly can effectively catalyze an unactivated phosphoric acid aryl diethyl ester compound and the alkyl group Grignard reagent to perform the reaction.
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Paragraph 0052
(2017/01/02)
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- Iron-catalyzed cross-coupling of heteroaromatic tosylates with alkyl and aryl Grignard reagents
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An Fe(III)-catalyzed cross-coupling of N-heteroaromatic tosylates with aryl and alkyl Grignard reagents is presented. The reaction proceeds at -20°C to room temperature with short reaction time (15-30 min.), and the corresponding products are obtained with moderate to high yields. In particular, low-cost and abundantly available FeCl3 or Fe(acetylacetonate)3 catalyze the reaction without other special ligands. All tested N-heteroaromatic tosylates that are available including pyridine and pyrimidine derivatives were subject to the reaction, resulting in the expected products.
- Chen, Xu,Quan, Zheng-Jun,Wang, Xi-Cun
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p. 296 - 300
(2015/04/27)
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- Chemo-controlled cross-coupling of Di(hetero)aryl disulfides with grignard reagents: C-C vs. C-S bond formation
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A general protocol for the chemoselectivity-controlled C-C and C-S coupling reactions of di(hetero)aryl disulfides with Grignard reagents catalyzed by ferrocene and palladium acetate has been developed. Ferrocene favored the formation of C-S coupled products at low temperature, whereas C-C bond couplings were favored when palladium acetate was used. All the reactions proceeded with excellent chemoselectivity and in good yields under mild conditions, and a library of molecules with pyridine and pyrimidine scaffolds was produced.
- Du, Bao-Xin,Quan, Zheng-Jun,Da, Yu-Xia,Zhang, Zhang,Wang, Xi-Cun
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supporting information
p. 1270 - 1276
(2015/04/22)
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- Copolymer-incarcerated nickel nanoparticles with N-heterocyclic carbene precursors as active cross-linking agents for Corriu-Kumada-Tamao reaction
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We have developed heterogeneous polymer-incarcerated nickel nanoparticles (NPs), which catalyze cross-coupling reactions. The matrix structure of these catalysts incorporates both N-heterocyclic carbenes (NHCs) as ligands and Ni-NPs, thanks to a new design of cross-linking agents in polymer supports. These embedded NHCs were detected by field gradient swollen-resin magic angle spinning NMR analysis. They were successfully applied to Corriu-Kumada-Tamao reactions with a broad substrate scope including functional group tolerance, and the catalyst could be recovered and reused several times without loss of activity.
- Soule, Jean-Francois,Miyamura, Hiroyuki,Kobayashi, Shu
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supporting information
p. 10602 - 10605
(2013/08/23)
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- Iron-catalyzed alkylations of aryl sulfamates and carbamates
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The alkylation of aryl sulfamates and carbamates using iron catalysis is reported. The method constructs sp2-sp3 carbon-carbon bonds and provides synthetically useful yields across a range of substrates (>35 examples). The directing group ability of sulfamates and carbamates, accompanied by their low reactivity toward conventional cross-couplings, renders these substrates useful for the synthesis of polyfunctionalized arenes.
- Silberstein, Amanda L.,Ramgren, Stephen D.,Garg, Neil K.
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supporting information; experimental part
p. 3796 - 3799
(2012/08/28)
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- Zn-promoted regio- and sequence-selective one-pot joining reactions of three components: vinylpyridines, alkyl iodides, and carbonyl compounds (or nitriles)
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Addition of alkyl iodides (3) into the solution containing 2-(or 4-)vinylpyridine (1 or 2) and carbonyl compounds (6) in the presence of Zn-powder (99.9%) in acetonitrile under refluxing brought about regio- and sequence-selective joining reaction of thre
- Mineyama, Kenji,Maekawa, Hirofumi,Kohsaka, Akihiro,Yamamoto, Yoshimasa,Nishiguchi, Ikuzo
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experimental part
p. 7706 - 7711
(2009/12/04)
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- Cobalt-catalyzed cross-coupling reaction of chloropyridines with grignard reagents
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Treatment of 2-chloropyridine with benzylmagnesium chloride in the presence of a catalytic amount of cobalt(II) acetylacetonate in dioxane afforded the corresponding cross-coupling product in excellent yield. Trimethylsilylmethyl and phenyl Grignard reagents also participated in similar cross-coupling reactions.
- Ohmiya, Hirohisa,Yorimitsu, Hideki,Oshima, Koichiro
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p. 1240 - 1241
(2007/10/03)
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- Iron catalyzed cross coupling reactions of aromatic compounds
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A process for the production of compounds Ar—R1 by means of a cross-coupling reaction of an organometallic reagent R1—M with an aromatic or heteroaromatic substrate Ar—X catalyzed by one or several iron salts or iron complexes as catalysts or pre-catalysts, present homogeneously or heterogeneously in the reaction mixture. This new invention exhibits substantial advantages over established cross coupling methodology using palladium- or nickel complexes as the catalysts. Most notable aspects are the fact that (i) expensive and/or toxic nobel metal catalysts are replaced by cheap, stable, commercially available and toxicologically benign iron salts or iron complexes as the catalysts or pre-catalysts, (ii) commercially attractive aryl chlorides as well as various aryl sulfonates can be used as starting materials, (iii) the reaction can be performed under “ligand-free” conditons, and (iv) the reaction times are usually very short.
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Page/Page column 5
(2010/02/03)
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- Iron-catalyzed cross-coupling reactions of alkyl-Grignard reagents with aryl chlorides, tosylates, and triflates
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Aryl chlorides are better substrates than the corresponding bromides or iodides in the presented cross-coupling with alkyl Grignard reagents that is catalyzed by iron salts (see scheme); even aryl tosylates are converted efficiently. This situation is att
- Fuerstner, Alois,Leitner, Andreas
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p. 609 - 612
(2007/10/03)
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- Iron-catalyzed cross-coupling reactions
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Simple iron salts such as FeCln, Fe(acac)n (n = 2,3) or the salen complex 4 turned out to be highly efficient, cheap, toxicologically benign, and environmentally friendly precatalysts for a host of cross-coupling reactions of alkyl o
- Fuerstner, Alois,Leitner, Andreas,Mendez, Maria,Krause, Helga
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p. 13856 - 13863
(2007/10/03)
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- Aggregative activation in heterocyclic chemistry. Part 5. Lithiation of pyridine and quinoline with the complex base BuLi·Me2N(CH2)2OLi (BuLi·LiDMAE)
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It is shown that the complex base BuLi·LiDMAE reacts with pyridine to give metallated species which, after trapping by electrophiles, lead to 2-substituted pyridines in good to excellent yields. The same reactions have been less successfully performed with quinoline.
- Gros, Philippe,Fort, Yves,Caubere, Paul
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p. 3597 - 3600
(2007/10/03)
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- A Convenient Palladium-Catalyzed Coupling Approach to 2,5-Disubstituted Pyridines
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2,5-Dibromopyridine has been found to undergo a regioselective palladium-catalyzed coupling reaction with terminal acetylenes and arylzinc halides to give the corresponding 2-alkynyl-5-bromo- and 2-aryl-5-bromopyridines, respectively, in 70percent-90percent isolated yields.To complement this chemistry, the triflate derived from 2-methyl-5-pyridinol was found to participate in a palladium-catalyzed reaction with terminal acetylenes leading to the corresponding 5-alkynyl-2-methylpyridines.These intermediates can be further manipulated to afford a broad range of 2,5-disubstituted pyridines.
- Tilley, Jefferson W.,Zawoiski, Sonja
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p. 386 - 390
(2007/10/02)
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- IPSO-SUBSTITUTION REACTIONS OF 2- AND 4-SULFONYLPYRIDINES WITH GRIGNARD REAGENTS
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The reactions of 2-sulfonylpyridines with Grignard reagents proceeded via an ionic path to give only the corresponding ipso-substitution products, while 4-sulfonylpyridines afforded mainly a mixture of both the substitution and coupling products on treatment with Grignard reagents.
- Furukawa, Naomichi,Tsuruoka, Masayuki,Fujihara, Hisashi
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p. 3337 - 3340
(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)
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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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- A REGIOSPECIFIC SYNTHESIS OF CARBOSUBSTITUTED HETEROAROMATIC DERIVATIVES VIA Pd-CATALYZED CROSS COUPLING
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The Pd-catalyzed cross-coupling reaction of either heteroarylzinc derivatives with unsaturated organic halides or heteroaryl halides with organometallic reagents containing Zn or Al can produce cleanly and regiospecifically the corresponding carbo-substituted heteroatomic compounds in high yields.
- Negishi, Ei-ichi,Luo, Fen-Tair,Frisbee, Roger,Matsushita, Hajime
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p. 117 - 122
(2007/10/02)
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