- The Use of Two Linked Scanning Modes in Alternation to Analyse Metastable Peaks
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Analyses of masses relative kinetic energies for metastable peaks may be achieved by the use in alternation of two types of linked scans of the electric sector voltage and magnetic field.The method is demonstrated by an appraisal of hydrogen exchange in molecular ions of 2-methyl-2H3>-benzoic acid.
- Lacey, Michael J.,Macdonald, Colin G.
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- Assembly of Tetrahydroquinolines and 2-Benzazepines by Pd-Catalyzed Cycloadditions Involving the Activation of C(sp3)-H Bonds
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Cycloaddition reactions are among the most practical strategies to assemble cyclic products; however, they usually require the presence of reactive functional groups in the reactants. Here, we report a palladium-catalyzed formal (4 + 2) cycloaddition that
- Vidal, Xandro,Mascare?as, José Luis,Gulías, Moisés
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p. 5323 - 5328
(2021/07/21)
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- Copper-Catalyzed Modular Access to N-Fused Polycyclic Indoles and 5-Aroyl-pyrrol-2-ones via Intramolecular N—H/C—H Annulation with Alkynes: Scope and Mechanism Probes
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Copper-catalyzed intramolecular N—H/C—H annulation with alkynes has been developed. A variety of densely functionalized heterocycles, such as pyrrolo[1,2-a]indoles, indolo[1,2-c]quinazolin-2-ones, oxazolo[3,4-a]indoles, and imidazo[1,5-a]indoles, were synthesized in an atom- and step-economical manner, owing to the high modularized feature of aniline moiety, the linker moiety, as well as the alkyne moiety. By simply changing the oxidant from di-tert-butyl peroxide (DTBP) to 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO), the reaction could readily be transformed to the aminooxygenation pathway, which grabs one oxygen atom from the TEMPO to generate 5-aroyl-pyrrol-2-ones. Mechanistic experiments indicate that vinyl radical is involved in this reaction and an amidyl-radical-initiated radical cascade might be responsible for this transformation.
- Liu, Yan-Hua,Song, Hong,Zhang, Chi,Liu, Yue-Jin,Shi, Bing-Feng
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supporting information
p. 1545 - 1552
(2020/09/09)
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- First-Row Transition Metal and Lithium Pyridine-ene-amide Complexes Exhibiting N- and C-Isomers and Ligand-Based Activation of Benzylic C-H Bonds
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Ene-amines Z-3-(2-pyridyl)-1-aza(2,6-iPr2-Ph)propene, (pynac)H, and 2-(2-pyridyl)-1-aza(2,6-R,R′-Ph)propene, (pyEA-ArRR′)H, were synthesized by condensation procedures; corresponding lithium or potassium ene-amides were prepared via standard deprotonation protocols. Addition of 2 equiv of (pynac)H to {(Me3Si)2N}2Fe(THF) or 2 Li(pynac) to FeBr2(THF)2 afforded (pynac)2Fe (1), while treatment of CrCl2(THF)2, MnCl2, FeBr2(THF)2, and CoCl2py4 with 2 equiv of (pyEA-AriPr2)K afforded pseudotetrahedral (pyEA-AriPr2)2M (2-M, M = Cr, Mn, Fe) and (pyEA-AriPr2)2Co-py (2-Co-py). Diamagnetic (κ-C,N-pyEA-AriPr2)3Co (3) was prepared in low yield (~7%) from CoCl2, and its Co-C(sp3) linkages are unusually low in field strength. Reactivity studies yielded little clean reactivity, but thermolysis of 2-Co-py afforded the bis-indolamide derivative {κ-N,N-N(C6H3(2-iPr)CMe2C(Me)(2-py)}2Co (5-Co), and related thermolyses of 2-M (M = Cr, Mn, Fe), conducted on NMR tube scales, generated related 5-M (M = Cr, Mn, Fe) at roughly the same rates. This observation prompted thermolyses of (pyEA-ArRR′)Li, which rearrange to their corresponding indolamides in >90% yields. Rate studies, accompanied by KIE and EIE observations, revealed that an initial hydrogen transfer is reversible and is likely to correspond to an anionic rearrangement, whereas C-C bond formation is rate-determining, as suggested by accompanying calculations. X-ray structure determinations of 1, 2-Fe, 2-Co-py, 3, and 5-Co were conducted.
- Lindley, Brian M.,Wolczanski, Peter T.,Cundari, Thomas R.,Lobkovsky, Emil B.
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supporting information
p. 4656 - 4668
(2015/10/28)
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- Palladium catalyzed acetoxylation of benzylic C-H bonds using a bidentate picolinamide directing group
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A general palladium catalyzed acetoxylation of benzylic C-H bonds has been developed. Picolinamides serve as an excellent directing group for the C-H activation of benzylic methyls. A wide range of 2-amino benzyl alcohol analogues were synthesized in good yields. The products demonstrated broad synthetic utilities toward various benzo-fused heterocycles. Mechanistic studies revealed the key rate-limiting C-H insertion step, which could be affected by the substitution pattern of the parent arene.
- Cheng, Tao,Yin, Weiyu,Zhang, Yi,Zhang, Yingnan,Huang, Yong
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supporting information
p. 1405 - 1411
(2014/03/21)
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- Palladium-catalyzed through-space C(sp3)-H and C(sp 2)-H bond activation by 1,4-palladium migration: Efficient synthesis of [3,4]-fused oxindoles
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Palladium two step: Linear anilides were converted into the title compounds in good to excellent yields through a palladium-catalyzed domino carbopalladation/1,4-palladium shift sequence. The C(sp3)-H activation involves a seven-membered pallad
- Piou, Tiffany,Bunescu, Ala,Wang, Qian,Neuville, Luc,Zhu, Jieping
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supporting information
p. 12385 - 12389
(2013/12/04)
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- H-D exchange reaction taking advantage of the synergistic effect of heterogeneous palladium and platinum mixed catalyst
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An effective and applicable deuteration method for alkyl-substituted aromatic compounds using a heterogeneous Pd/C and Pt/C mixed catalyst in deuterium oxide in the presence of a small amount of hydrogen gas was developed. Mixing a heterogeneous palladium
- Ito, Nobuhiro,Watahiki, Tsutomu,Maesawa, Tsuneaki,Maegawa, Tomohiro,Sajiki, Hironao
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p. 1467 - 1478
(2008/12/21)
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- Synthesis of polydeuterated benzothiazoles via supercritical deuteration of anilines
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2-[2H]Benzothiazole, readily available according to the literature, was observed to undergo slow isotope exchange in water. This necessitated development of practical syntheses for benzothiazoles carrying deuterium labels in positions other than 2. [4,5,6,7-2H4]Benzothiazole and 4-[2H3]methyl[5,6,7-2H3]benzothiazole were prepared in good yields from [2H7]aniline and 2-[2H9]toluidine, which were obtained by novel rapid isotope exchange in supercritical deuterium oxide.
- Junk, Thomas,Catallo, W. James,Civils, L. Dana
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p. 625 - 630
(2007/10/03)
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