Carbon-oxygen Double Bond Research Articles

Copper-catalyzed difunctionalization of activated alkynes by radical oxidation-tandem cyclization/dearomatization to synthesize 3-trifluoromethyl spiro[4.5]trienones.

A copper-catalyzed difunctionalizing trifluoromethylation of activated alkynes with the cheap reagent sodium trifluoromethanesulfinate (NaSO2CF3 or Langlois' reagent) has been developed incorporating a tandem cyclization/dearomatization process. This strategy affords a straightforward route to synthesis of 3-(trifluoromethyl)-spiro[4.5]trienones, and presents an example of difunctionalization of alkynes for simultaneous formation of two carbon-carbon single bonds and one carbon-oxygen double bond.

New route to access an acyl-functionalized phosphasilene and a four-membered Si-P-C-O heterocycle.

An acyl-functionalized phosphasilene, LSi(COtBu)=P(SiMe3) (L = PhC(NtBu)2) was synthesized on a new route by the addition of tBuCOCl to the phosphinosilylene LSiP(SiMe3)2 and subsequent Me3SiCl elimination. DFT studies elucidated its molecular structure, the influence of the acyl group on UV/Vis transitions, and revealed the mechanism. The intermediate LSi(COtBu)ClP(SiMe3)2, with a five-coordinate silicon center, was characterized by NMR spectroscopy and X-ray analysis. On the other hand, phosphasilene LSi(SiMe3)=P(SiMe3) reacted with tBuCOCl by a [2+2] cycloaddition of the silicon-phosphorus double bond and the carbon-oxygen double bond in addition to Me3SiCl elimination, thereby affording the novel, fully characterized compound LSi(SiMe3)[P=C(tBu)O] bearing a Si-P-C-O heterocycle with a phosphorus-carbon double bond. DFT studies suggest that two mechanisms occur simultaneously.

4+2] cycloaddition of intermediates generated from arynes and DMF

The trapping reaction of the transient intermediate ortho-quinone methides, generated by the insertion of arynes into a carbon–oxygen double bond of DMF, with dienophiles was investigated. The [4+2] cycloaddition products were obtained when the diesters of acetylenedicarboxylic acid were employed as dienophiles.

Progress in Hydrosilylation Catalyzed with Iron Catalyst

Iron catalysts gained great development in hydrosilylation of various types of unsaturated double bond compounds due to their advantages of high raw material abundance, low cost, low toxicity, etc. The applications of iron catalysts are summarized in the hydrosilylation of carbon-carbon double bond, carbon-oxygen double bond and other heteroatomic double bond. The application prospect of iron catalysts in the field of organic silicon chemistry is looked forward.

Free Standing Reduced Graphene Oxide Film Cathodes for Lithium Ion Batteries

We report the fabrication and electrochemical activity of free-standing reduced graphene oxide (RGO) films as cathode materials for lithium ion batteries. The conducting additive and binder-free RGO electrodes with different oxygen contents were assembled by a simple vacuum filtration process from aqueous RGO colloids prepared with the aid of cationic surfactants. The gravimetric capacity of RGO film cathodes showed clear dependence on the oxygen contents controlled by the thermal reduction process. The capacity increased with the increase of the amount of oxygen functional groups, indicating that the main lithium capturing mechanism of RGO cathodes is Li(+) ion interaction with the surface oxygen functionalities. The hydroxyl groups (C-OH) as well as carbon-oxygen double bonds have been identified as the lithiation-active species. The RGO cathodes achieved excellent rate capability due to the fast surface Faradaic reaction, suggesting that self-supported RGO films are promising cathodes for high power application. The graphene oxide (GO)/RGO composite films showed inferior performance to those of RGO only. The poor electronic conductivity of GO might result in inefficient utilization of redox active oxygen functional groups despite the higher oxygen content and higher theoretical capacity of GO/RGO composite films. Further optimization on the amount of oxygen functional groups for higher capacity and better electronic conductivity would lead to the development of RGO based high energy-high power cathodes.

Chemoselective Formal [4+2] Cycloaddition of 3‐Hydroxycyclobutanones with Enones

Choice cuts: The formal [4+2] cycloaddition of 3-hydroxycyclobutanones to α,β-unsaturated ketones proceeds chemoselectively at the α,β-carbon–carbon double bond to afford cyclohexanone derivatives by using boron trifluoride etherate as a Lewis acid. In contrast, 3-ethoxycyclobutanone reacts at the carbonyl carbon–oxygen double bond to give dihydro-γ-pyrones. As a service to our authors and readers, this journal provides supporting information supplied by the authors. Such materials are peer reviewed and may be re-organized for online delivery, but are not copy-edited or typeset. Technical support issues arising from supporting information (other than missing files) should be addressed to the authors. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.

ChemInform Abstract: Enantioselective Cycloaddition Reactions of Ketenes Catalyzed by N‐Heterocyclic Carbenes

AbstractReview: 94 refs.

The X-ray Crystal Structure of a Cuprate-Carbonyl π-Complex

Complexes between copper reagents and double-bonds have been proposed as intermediates in a number of synthetically important reactions. Many h-complexes between organocuprates and carbon–carbon double-bonds, which are intermediates in 1,4-addition reactions of a,b-unsaturated carbonyl compounds, have been observed by using NMR spectroscopy. Moreover, h-O,C-complexes between organocopper compounds and carbon–oxygen double-bonds have been proposed as intermediates in 1,2-additions to carbonyl compounds, for example, copper-catalyzed asymmetric induction reactions. Carbophilic additions to thiocarbonyl compounds, mediated by organocuprates, have been explained in terms of h-S,C-complexes of carbon–sulfur double-bonds. However, there has been no report of an X-ray structure for any of these p-complexes. Therefore, we applied our rapid-injection techniques, which were previously used to prepare several important intermediates, to screen a number of typical aldehydes and ketones for complex formation with Me2CuLi, [9] and we discovered such a species with unusual stability, which has allowed us to prepare it on a larger scale and grow highquality crystals (see the Supporting Information). We now report the first X-ray crystal structure of a cuprate– carbonyl p-complex, 1 (Scheme 1 and Figure 1).

Enantioselective Cycloaddition Reactions of Ketenes Catalyzed by N-Heterocyclic Carbenes

This account summarizes recent research in our group on the development of N-heterocyclic carbene (NHC) catalyzed cycloaddition reactions of ketenes. The NHCs were found to be efficient catalysts for the enantioselective [2+2]-, [2+2+2]-, [3+2]-, and [4+2]-cycloaddition reactions of ketenes with various electrophiles, such as imines, carbonyl compounds, oxaziridines, oxodienes and azadienes. The NHC-catalyzed [4+2] cycloaddition of α,β-unsaturated acyl chlorides was also investigated. 1 Introduction 2 [2+2] Cycloaddition of Ketenes 2.1 With Carbon–Nitrogen Double Bonds 2.2 With Carbon–Oxygen Double Bonds 2.3 With Oxygen–Nitrogen and Nitrogen–Nitrogen Double Bonds 2.4 With X=Y=Z Bonds 3 [3+2] Cycloaddition of Ketenes 4 [4+2] Cycloaddition of Ketenes 5 [4+2] Annulation of Unsaturated Acyl Chlorides 6 Conclusions and Outlook

Mechanism and kinetic study on the gas-phase reactions of OH radical with carbamate insecticide isoprocarb

As one of the most important carbamate insecticides, isoprocarb [2-(1-methylethyl) phenyl methylcarbamate, MIPC] is widely used in agricultural and cotton spraying. The atmospheric chemical reaction mechanism and kinetics of MIPC with OH radical have been researched using the density functional theory in this paper. The study shows that OH radical is more easily added to the C atoms of aromatic ring than to carbon-oxygen double bond, while the H atom is abstracted more difficulty from –CONH– group and aromatic ring than from the –CH3– group and the –CH– group. At room temperature, the total rate constant of MIPC with OH radical is about 5.1 × 10−12 cm3 molecule−l s−l. OH radical addition reaction and H atom abstraction reaction are both important for the OH-initiated reaction of MIPC. The energy-rich adducts (MIPC-OH) and the MIPC's radical isomers are open-shell activated radicals and can be further oxidized in the atmosphere.

A stable germanone as the first isolated heavy ketone with a terminal oxygen atom

The carbon-oxygen double bond of ketones (R(2)C=O) makes them among the most important organic compounds, but their homologues, heavy ketones with an E=O double bond (E=Si, Ge, Sn or Pb), had not been isolated as stable compounds. Their unavailability as monomeric molecules is ascribed to their high tendency for intermolecular oligomerization or polymerization via opening of the E=O double bond. Can such an intermolecular process be inhibited by bulky protecting groups? We now report that it can, with the first isolation of a monomeric germanium ketone analogue (Eind)(2)Ge=O (Eind=1,1,3,3,5,5,7,7-octaethyl-s-hydrindacen-4-yl), stabilized by appropriately designed bulky Eind groups, with a planar tricoordinate germanium atom. Computational studies and chemical reactions suggest the Ge=O double bond is highly polarized with a contribution of a charge-separated form (Eind)(2)Ge(+)-O(-). The germanone thus exhibits unique reactivities that are not observed with ordinary ketones, including the spontaneous trapping of CO(2) gas to provide a cyclic addition product.

Characterization of urban aerosol using aerosol mass spectrometry and proton nuclear magnetic resonance spectroscopy

Particulate matter was measured during August and September of 2006 in Houston as part of the Texas Air Quality Study II Radical and Aerosol Measurement Project. Aerosol size and composition were determined using an Aerodyne quadrupole aerosol mass spectrometer. Aerosol was dominated by sulfate (4.1 ± 2.6 μg m−3) and organic material (5.5 ± 4.0 μg m−3), with contributions of organic material from both primary (∼32%) and secondary (∼68%) sources. Secondary organic aerosol appears to be formed locally. In addition, 29 aerosol filter samples were analyzed using proton nuclear magnetic resonance (1H NMR) spectroscopy to determine relative concentrations of organic functional groups. Houston aerosols are less oxidized than those observed elsewhere, with smaller relative contributions of carbon-oxygen double bonds. These particles do not fit 1H NMR source apportionment fingerprints for identification of secondary, marine, and biomass burning organic aerosol, suggesting that a new fingerprint for highly urbanized and industrially influenced locations be established.

Insertion of arynes into the carbon–oxygen double bond of amides and its application into the sequential reactions

The reaction of arynes, generated from ortho-(trimethylsilyl)aryl triflates, with the CO bond of formamides gave salicylaldehyde derivatives via the formation of formal [2+2] adducts. The sequential transformation of arynes into ortho-disubstituted arenes, o-aminoalkylphenols or o-hydroxyalkylphenols, was achieved by one-pot procedure using dialkylzincs.

A photoswitchable orange-to-far-red fluorescent protein, PSmOrange

We report a monomeric PSmOrange protein that is initially orange (excitation and emission at 548 and 565 nm) but becomes far-red (excitation and emission at 636 and 662 nm) after irradiation with blue-green light. Compared to its parental orange proteins, PSmOrange has greater brightness, faster maturation, higher photoconversion contrast, and better photostability. The red-shifted spectra of both forms of PSmOrange enable its simultaneous use with cyan-to-green photoswitchable proteins to study four intracellular populations. Photoconverted PSmOrange has, to date, the most far-red excitation peak, provides diffraction-limited and super-resolution imaging in far-red range, is optimally excited with common red lasers, and can be photoconverted subcutaneously in a mouse. PSmOrange photoswitching occurs via a two-step photo-oxidation process, which causes cleavage of the polypeptide backbone. The far-red fluorescence of photoconverted PSmOrange results from a novel chromophore containing N-acylimine with a coplanar carbon-oxygen double bond.

13C Solid State NMR Suggests Unusual Breakdown Products in SEI Formation on Lithium Ion Electrodes

This study investigates the organic components of the solid electrolyte interphase (SEI) on the carbonaceous anodic electrode in LiCoO2 batteries using solid-state nuclear magnetic resonance (NMR) techniques. The electrolyte solvents, ethylene carbonate and diethyl carbonate, were enriched on the carbonyl carbon prior to cell assembly and conditioning in an attempt to trace the breakdown pathways of these components. A strong signal was seen, demonstrating that the carbonyl carbons of both electrolytes survive in some reasonable quantity as insoluble breakdown products on the rinsed electrode surface. This confirms that the fate of these carbons as consumed in the formation of CO2 is either not unique, or not as final product. Furthermore the central carbonyl carbon survives, not as an intact carbonyl species, but instead in the form of compounds in which the carbon-oxygen double bond has been disrupted. Formation of this class of species is likely initiated by a nucleophilic attack on the carbonyl carbon by one or more radical, alkoxy, carbanion or fluorine-containing ionic species formed from solvent and/or salt breakdown. These results suggest a new family of electrolyte breakdown products, predominantly consisting of binary, tertiary and/or quaternary ether-type compounds (i.e., orthocarbonates and orthoesters), as well as fluorine-containing alkoxy compounds.

ChemInform Abstract: Asymmetric Induction in Additions to Carbon-Oxygen and Carbon-Nitrogen Double Bonds

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Synthesis and Reaction of Monomeric Germanium(II) and Lead(II) Dimethylamide and the Synthesis of Germanium(II) Hydrazide by Clevage of one N−H bond of Hydrazine

The beta-diketiminate substituted germanium(II) and lead(II) dimethylamides, LGeNMe(2) (1) and LPbNMe(2) (2), [L = CH{(CMe)(2)(2,6-iPr(2)C(6)H(3)N)(2)}] have been synthesized by the reaction of LiNMe(2) with LGeCl and LPbCl respectively. Reaction of compound 1 with an equivalent amount of elemental sulfur leads to the germanium analogue of thioamide, LGe(S)NMe(2) (3). 2 reacts with 2-benzoyl pyridine (PhCOPy-2) to form the lead(II) alkoxide LPbOC(NMe(2))Ph(2-Py) (4) by nucleophilic addition of "NMe(2)" to the carbon oxygen double bond. The reaction of stable N-heterocyclic germylene L(1)Ge [L(1) = CH{(C=CH(2))(CMe)(2,6-iPr(2)C(6)H(3)N)(2)}] with hydrazine yields the germanium(II) substituted hydrazide LGeNHNH(2) (5) by cleavage of one N-H bond of hydrazine. Finally, attempts to isolate lead(II) hydride LPbH from the reaction of 2 with phenylsilane (PhSiH(3)) failed, and instead LPbN(2,6-iPr(2)C(6)H(3)){C(CH(3))CHC(CH(3))=N(2,6-iPr(2)C(6)H(3))} (6) was obtained in very low yield. We are able to prove this only by single crystal X-ray structural analysis. Compounds 1, 2, 3, 4, and 5 were characterized by microanalysis, electron impact (EI) mass spectrometry, and multinuclear NMR spectroscopy. Furthermore compounds 1, 2, 5, and 6 were characterized by single crystal X-ray structural analysis, with the result that they are exhibiting monomeric structures in the solid state with trigonal-pyramidal environment at the metal center and a stereochemically active lone pair.

Chemoselective reaction of cyanoacetic acid with benzal-4-acetylanilines and fungitoxicity of products

Cyanoacetic acid reacted chemoselectively with carbon-nitrogen double bond of benzal-4-acetylaniliines, leaving the carbon-oxygen double bond, considered to be more reactive, intact, leading to the formation of mono addition-elimination products rather than bis attack at both the reactive centres, even when the reaction was carried out with two moles of cyanoacetic acid. The product viz. benzalcyanoacetic acid and its derivatives were screened for their fungitoxicity against five pathogenic fungi.

Synthetic Utility of N-Sulfonylimines

Analogous to carbon-carbon and carbon-oxygen double bonds, carbon-nitrogen double bond has been an active site of study in recent times. The reactivity of the carbon-nitrogen double bond lies in between that of the carbonyl and olefinic functions. The carbon-nitrogen double bond has an additional lone pair of electrons which leads to its distinctive properties from carbon-carbon double bond.

Interaction of water vapor with gamma-radiation-induced defects in proton conductive polymers

The correlation between protonic conduction and the amount of radiation-induced defects in gamma-ray-irradiated perfluorosulfonic acid (PFSA) polymers (Aciplex-SF-1004 ®) has been investigated using a direct-current resistance method, transmission spectroscopy for the ultraviolet (UV) and visible (Vis) wavelength ranges and Fourier transform infrared (FTIR) spectroscopy with the attenuated total refraction (ATR) technique. The proton conductivity of the polymers, which are irradiated with a dose of up to 532 kGy under vacuum at room temperature and subsequently exposure to air, is enhanced by approximately three orders of magnitude as compared to that of the unirradiated polymer. The UV–Vis spectra of the irradiated polymers reveal the presence of fluorocarbon radicals, which increase with the irradiation dose. It is also observed in the UV–Vis and FTIR spectra that peroxy free radicals, unsaturated species (COF), and a carboxyl group (COOH) containing a carbon-oxygen double bond are formed by reactions of the fluorocarbon radicals with oxygen or water vapor in air. In addition, an increase in the hydrogen concentration is observed in the near-surface regions of the irradiated polymers by using an elastic recoil detection (ERD) technique. The production of charge carriers such as protons and oxonium ions (H 3O +) by the interaction of water vapor with the activating-radiation-induced defects leads to the enhancement of the proton conductivity.