125415

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Hyperaromatic stabilization of arenium ions.

Jaya S Kudavalli et al.

Organic letters, 12(23), 5550-5553 (2010-11-09)

Benzene-cis- and trans-1,2-dihydrodiols undergo acid-catalyzed dehydration at remarkably different rates: k(cis)/k(trans) = 4500. This is explained by formation of a β-hydroxycarbocation intermediate in different initial conformations, one of which is stabilized by hyperconjugation amplified by an aromatic no-bond resonance structure

Dual reactivity of hydroxy- and methoxy- substituted o-quinone methides in aqueous solutions: hydration versus tautomerization.

Selvanathan Arumugam et al.

The Journal of organic chemistry, 75(21), 7338-7346 (2010-10-12)

4-Hydroxy-6-methylene-2,4-cyclohexadien-1-one (1) and 4-methoxy-6-methylene-2,4-cyclohexadien-1-one (2) were generated by efficient (Φ = 0.3) photodehydration of 2-(hydroxymethyl)benzene-1,4-diol (3a) and 2-(hydroxymethyl)-4-methoxyphenol (4a), respectively. o-Quinone methides 1 and 2 can be quantitatively trapped as Diels-Alder adducts with ethyl vinyl ether or intercepted by good

Aliphatic C-H bond activation initiated by a (mu-eta2:eta2-peroxo)dicopper(II) complex in comparison with cumylperoxyl radical.

Takahiro Matsumoto et al.

Journal of the American Chemical Society, 131(26), 9258-9267 (2009-06-18)

A (mu-eta(2):eta(2)-peroxo)dicopper(II) complex, [Cu(2)(H-L)(O(2))](2+) (1-O(2)), supported by the dinucleating ligand 1,3-bis[bis(6-methyl-2-pyridylmethyl)aminomethyl]benzene (H-L) is capable of initiating C-H bond activation of a variety of external aliphatic substrates (SH(n)): 10-methyl-9,10-dihydroacridine (AcrH(2)), 1,4-cyclohexadiene (1,4-CHD), 9,10-dihydroanthracene (9,10-DHA), fluorene, tetralin, toluene, and tetrahydrofuran (THF), which

Correlating DFT-calculated energy barriers to experiments in nonheme octahedral Fe(IV)O species.

Kyung-Bin Cho et al.

Chemistry (Weinheim an der Bergstrasse, Germany), 18(33), 10444-10453 (2012-06-21)

The experimentally measured bimolecular reaction rate constant, k(2), should in principle correlate with the theoretically calculated rate-limiting free energy barrier, ΔG(≠), through the Eyring equation, but it fails quite often to do so due to the inability of current computational

Catalytic desymmetrization of cyclohexadienes by asymmetric bromolactonization.

Kazutada Ikeuchi et al.

Organic letters, 14(23), 6016-6019 (2012-11-15)

Asymmetric bromolactonization of prochiral cyclohexadiene derivatives with N-bromosuccimide proceeded in the presence of (DHQD)(2)PHAL as a chiral catalyst to afford the corresponding bromolactones with up to 93% ee. This reaction was also applicable to the kinetic resolution of a racemic

Enthalpy of formation of the cyclohexadienyl radical and the C-H bond enthalpy of 1,4-cyclohexadiene: an experimental and computational re-evaluation.

Yide Gao et al.

The journal of physical chemistry. A, 113(25), 6955-6963 (2009-06-06)

A quantitative understanding of the thermochemistry of cyclohexadienyl radical and 1,4-cyclohexadiene is beneficial for diverse areas of chemistry. Given the interest in these two species, it is surprising that more detailed thermodynamic data concerning the homolytic C-H bond enthalpies of

Selective molecular sequestration with concurrent natural product functionalization and derivatization: from crude natural product extracts to a single natural product derivative in one step.

Viktor Krchňák et al.

The Journal of organic chemistry, 76(24), 10249-10253 (2011-11-09)

A resin-bound nitroso compound sequestered a single unexpected component from crude plant seed extracts. Several plants, including Piper nigrum, Eugenia caryophyllata, and Pimenta dioica, were extracted with organic solvent in the presence of a nitroso-containing resin. The nitroso resin selectively

A key factor in parent and fragment ion formation on irradiation with an intense femtosecond laser pulse.

Harada H, et al.

Chemical Physics Letters, 342(5), 563-570 (2001)

Oxidative properties of a nonheme Ni(II)(O2) complex: Reactivity patterns for C-H activation, aromatic hydroxylation and heteroatom oxidation.

Reza Latifi et al.

Chemical communications (Cambridge, England), 47(38), 10674-10676 (2011-09-06)

Density functional theory calculations on the reactivity of a Ni(II)-superoxo complex in C-H bond activation, aromatic hydroxylation and heteroatom oxidation reactions have been explored; the Ni(II)-superoxo complex is able to react with substrates with weak C-H bonds and PPh(3).

Synthesis of enantiopure trans-N-Boc-3-aminobicyclo[2.2.2]octane-2-carboxylic acids and their bicyclic 1,3-amino alcohol derivatives via the [4+2] cycloaddition of 1,3-cyclohexadiene to a chiral β-nitroacrylate.

Monique Calmes et al.

Chirality, 23(3), 245-249 (2010-10-12)

The chiral β-nitroacrylate 2 derived from the (R)- or (S)-4-(3-hydroxy-4,4-dimethyl-2-oxopyrrolidin-1-yl) benzoic acid 1 acts as a reactive dienophile in a diastereoselective Diels-Alder reaction with 1,3-cyclohexadiene. The major cycloadducts have been isolated and transformed into enantiopure trans(2S,3S)- or (2R,3R)-N-Boc-3-aminobicyclic[2,2,2]octane-2-carboxylic acids 5.

Unravelling the details of vitamin D photosynthesis by non-adiabatic molecular dynamics simulations.

Enrico Tapavicza et al.

Physical chemistry chemical physics : PCCP, 13(47), 20986-20998 (2011-10-25)

We investigate the photodynamics of vitamin D derivatives by a fully analytical implementation of the linear response time-dependent density functional theory surface hopping method (LR-TDDFT-SH). Our study elucidates the dynamics of the processes involved in vitamin D formation at the

Rapid removal of protecting groups from peptides by catalytic transfer hydrogenation with 1, 4-cyclohexadiene.

Felix AM,et al.

The Journal of Organic Chemistry, 43(21), 4194-4196 (1978)

Transforming terpene feedstock into polyketide architecture.

Philipp Winter et al.

Chemical communications (Cambridge, England), 47(1), 394-396 (2010-09-14)

The Cu-catalyzed synthesis of skipped 1,4-dienes from allylic acetates and vinyl-Grignard reagents is key to bidirectional modifications of acyclic terpene acetates. As a result, trisubstituted double bond containing subunits can be readily transferred into complex polyketides from inexpensive bulk terpenes.

Shapeshifting: ligation by 1,4-cyclohexadiene induces a structural change in Ag5(+).

William A Donald et al.

Dalton transactions (Cambridge, England : 2003), 41(11), 3185-3193 (2012-01-31)

Relatively little is known about structural transformations of very small metal clusters that result from the adsorption of molecules. Here, the ligand-induced structural transformation of Ag(5)(+)(g) by 1,4-cyclohexadiene, which is capable of binding metal clusters as a bidentate ligand, is

Directed epoxidation of cyclohexa-1,4-dienes-stereoselective formation of up to six contiguous stereogenic centres.

Michael Butters et al.

Organic & biomolecular chemistry, 6(23), 4426-4434 (2008-11-14)

Epoxidation/cyclisation of cyclohexa-1,4-dienes containing pendant hydroxyl groups provides stereocontrolled access to highly-functionalised reduced benzol[b]furan derivatives.

Redox inactive metal ion triggered N-dealkylation by an iron catalyst with dioxygen activation: a lesson from lipoxygenases.

Jisheng Zhang et al.

Dalton transactions (Cambridge, England : 2003), 44(21), 9847-9859 (2015-05-06)

Utilization of dioxygen as the terminal oxidant at ambient temperature is always a challenge in redox chemistry, because it is hard to oxidize a stable redox metal ion like iron(III) to its high oxidation state to initialize the catalytic cycle.

Mechanistic insight into the palladium-catalyzed 1,4-oxidation of 1,3-dienes to 1,4-dicarboxy-alk-2-enes.

Martin D Eastgate et al.

Angewandte Chemie (International ed. in English), 48(32), 5958-5961 (2009-07-02)

Transient X-ray fragmentation: probing a prototypical photoinduced ring opening.

Vladimir S Petrović et al.

Physical review letters, 108(25), 253006-253006 (2012-09-26)

We report the first study of UV-induced photoisomerization probed via core ionization by an x-ray laser. We investigated x-ray ionization and fragmentation of the cyclohexadiene-hexatriene system at 850 eV during the ring opening. We find that the ion-fragmentation patterns evolve

Diffusion controlled hydrogen atom abstraction from tertiary amines by the benzyloxyl radical. The importance of C-H/N hydrogen bonding.

Michela Salamone et al.

Organic letters, 13(2), 260-263 (2010-12-15)

The rate constants for H-atom abstraction (k(H)) from 1,4-cyclohexadiene (CHD), triethylamine (TEA), triisobutylamine (TIBA), and DABCO by the cumyloxyl (CumO(•)) and benzyloxyl (BnO(•)) radicals were measured. Comparable k(H) values for the two radicals were obtained in their reactions with CHD

Valuable new cyclohexadiene building blocks from cationic η5-iron-carbonyl complexes derived from a microbial arene oxidation product.

Monika Ali Khan et al.

Chemistry (Weinheim an der Bergstrasse, Germany), 18(42), 13480-13493 (2012-09-15)

Biooxidation of benzoic acid by Ralstonia eutropha B9 provides an unusual cyclohexadiene carboxy diol that contains a quaternary stereocentre. Tricarbonyliron derivatives of this chiron, on treatment with acid, give two isomeric η(5)-cyclohexadienyl complexes as observed by NMR spectroscopy. Both of

Organometallics, 25, 5456-5456 (2006)

Opportunistic use of tetrachloroaurate photolysis in the generation of reductive species for the production of gold nanostructures.

Katherine L McGilvray et al.

Physical chemistry chemical physics : PCCP, 13(25), 11914-11918 (2011-06-01)

The photolysis of gold salts is rarely viewed as the initiation for gold nanoparticle (AuNP) formation. Yet, photolysis of AuCl(4)(-) generates chlorine atoms whose rich hydrogen transfer chemistry can readily generate strongly reducing radicals. Interesting precursors include hydrogen peroxide, 2-propanol

Desymmetrization of hydrazinocyclohexadienes: a new approach for the synthesis of polyhydroxylated aminocyclohexanes.

Gauthier Errasti et al.

Organic letters, 11(13), 2912-2915 (2009-05-28)

Hydrazinocyclohexadienes, easily prepared by an ene-reaction between commercially available azodicarboxylate reagents and cyclohexadiene, are interesting substrates for desymmetrization reactions. Under Sharpless asymmetric dihydroxylation conditions, they can lead efficiently to several chiral building blocks as well as advanced precursors of biologically

Mechanistic insights into the reactions of hydride transfer versus hydrogen atom transfer by a trans-dioxoruthenium(VI) complex.

Sunder N Dhuri et al.

Dalton transactions (Cambridge, England : 2003), 44(16), 7634-7642 (2015-03-27)

A mononuclear high-valent trans-dioxoruthenium(VI) complex, trans-[Ru(VI)(TMC)(O)2](2+) (TMC = 1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecane), was synthesized and characterized by various spectroscopic techniques and X-ray crystallography. The reactivity of the trans-[Ru(VI)(TMC)(O)2](2+) complex was investigated in hydride transfer and hydrogen atom transfer reactions. The mechanism of hydride

Accessing the antipodal series in microbial arene oxidation: a novel diene rearrangement induced by tricarbonyliron(0) complexation.

Monika Ali Khan et al.

Chemical communications (Cambridge, England), 47(1), 215-217 (2010-08-24)

A cyclohexadiene ligand prepared by microbial arene 1,2-dihydroxylation undergoes spontaneous rearrangement upon complexation to tricarbonyliron(0). Subsequent iron removal affords a novel route to formal arene 2,3-dihydroxylation products enantiomeric to those obtainable by direct microbial arene oxidation.

Hyaladione, an S-methyl cyclohexadiene-dione from Hyalangium minutum.

Patrick W Okanya et al.

Journal of natural products, 75(4), 768-770 (2012-04-14)

A bioassay-guided fractionation of the crude methanol extract of the myxobacterium Hyalangium minutum, strain NOCB-2(T) (DSM 14724(T)), led to the isolation of hyaladione (1), a novel S-methyl cyclohexadiene-dione. The structure of 1 was established by HRESIMS, NMR, and IR spectroscopy

Reactivity of copper(II)-alkylperoxo complexes.

Tetsuro Tano et al.

Dalton transactions (Cambridge, England : 2003), 40(40), 10326-10336 (2011-08-03)

Copper(II) complexes 1a and 1b, supported by tridentate ligand bpa [bis(2-pyridylmethyl)amine] and tetradentate ligand tpa [tris(2-pyridylmethyl)amine], respectively, react with cumene hydroperoxide (CmOOH) in the presence of triethylamine in CH(3)CN to provide the corresponding copper(II) cumylperoxo complexes 2a and 2b, the

Enzymes involved in the biodegradation of hexachlorocyclohexane: a mini review.

Beni Camacho-Pérez et al.

Journal of environmental management, 95 Suppl, S306-S318 (2011-10-14)

The scope of this paper encompasses the following subjects: (i) aerobic and anaerobic degradation pathways of γ-hexachlorocyclohexane (HCH); (ii) important genes and enzymes involved in the metabolic pathways of γ-HCH degradation; (iii) the instrumental methods for identifying and quantifying intermediate

Nonheme iron-oxo and -superoxo reactivities: O2 binding and spin inversion probability matter.

Kyung-Bin Cho et al.

Chemical communications (Cambridge, England), 48(16), 2189-2191 (2012-01-19)

DFT calculated barriers for C-H activation of 1,4-cyclohexadiene by nonheme iron(IV)-oxo and iron(III)-superoxo species show that the experimental trends can be explained if the spin inversion probability of the TMC iron(IV)-oxo is assumed to be poor. Also, the TMC iron(III)-superoxo

A new method for investigating infrared spectra of protonated benzene (C6H7+) and cyclohexadienyl radical (c-C6H7) using para-hydrogen.

Mohammed Bahou et al.

The Journal of chemical physics, 136(15), 154304-154304 (2012-04-24)

We use protonated benzene (C(6)H(7)(+)) and cyclohexadienyl radical (c-C(6)H(7)) to demonstrate a new method that has some advantages over other methods currently used. C(6)H(7)(+) and c-C(6)H(7) were produced on electron bombardment of a mixture of benzene (C(6)H(6)) and para-hydrogen during

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