Showing papers on "Double bond published in 2015"
TL;DR: A silver-catalyzed radical cascade process involving the sequential formation of two new C-C bonds and one C-N bond, a formal 1,4-aryl migration, and desulfonylation of the starting material explains the regioselective formation of densely functionalized heterocycles in a straightforward manner.
Abstract: The addition of a variety of radicals to the double bond of N-(arylsulfonyl)acrylamides can trigger cyclization/aryl migration/desulfonylation cascades via amidyl radical intermediates 2. Herein, we demonstrate the synthetic utility of these intermediates in subsequent C–C and C–X bond-forming events to rapidly build up molecular complexity. First, we describe a regioselective one-pot synthesis of CF3-, SCF3-, Ph2(O)P-, and N3-containing indolo[2,1-a]isoquinolin-6(5H)-ones from N-[(2-ethynyl)arylsulfonyl]acrylamides through a multi-step radical reaction cascade. The process involves the one-pot formation of four new bonds (one C–X, two C–C, and one C–N), a formal 1,4-aryl migration, and desulfonylation of the starting material. Second, we present a one-pot synthesis of 3,3-disubstituted-2-dihydropyridinones from N-(arylsulfonyl)acrylamides and 1,3-dicarbonyl compounds. In this case, a silver-catalyzed radical cascade process involving the sequential formation of two new C–C bonds and one C–N bond, a forma...
317 citations
TL;DR: The rhodium-catalysed carboamination of alkenes at the same (syn) face of a double bond, initiated by a carbon–hydrogen activation event that uses enoxyphthalimides as the source of both the carbon and the nitrogen functionalities, allows for the intermolecular, stereospecific formation of one carbon–carbon and one carbon-nitrogen bond across an alkene, which is, to the authors' knowledge, unprecedented.
Abstract: Alkenes are the most ubiquitous prochiral functional groups--those that can be converted from achiral to chiral in a single step--that are accessible to synthetic chemists. For this reason, difunctionalization reactions of alkenes (whereby two functional groups are added to the same double bond) are particularly important, as they can be used to produce highly complex molecular architectures. Stereoselective oxidation reactions, including dihydroxylation, aminohydroxylation and halogenation, are well established methods for functionalizing alkenes. However, the intermolecular incorporation of both carbon- and nitrogen-based functionalities stereoselectively across an alkene has not been reported. Here we describe the rhodium-catalysed carboamination of alkenes at the same (syn) face of a double bond, initiated by a carbon-hydrogen activation event that uses enoxyphthalimides as the source of both the carbon and the nitrogen functionalities. The reaction methodology allows for the intermolecular, stereospecific formation of one carbon-carbon and one carbon-nitrogen bond across an alkene, which is, to our knowledge, unprecedented. The reaction design involves the in situ generation of a bidentate directing group and the use of a new cyclopentadienyl ligand to control the reactivity of rhodium. The results provide a new way of synthesizing functionalized alkenes, and should lead to the convergent and stereoselective assembly of amine-containing acyclic molecules.
185 citations
TL;DR: GO plays a sacrificial role via the oxidation of (C[double bond, length as m-dash]C) carbon domains, and transferring electrons to Fe3O4, and confers superior catalytic efficiency, recyclability and longevity, otherwise not available in Fe 3O4.
170 citations
TL;DR: Regioselective double functionalization can be achieved in good to excellent yields, with a switch between light and dark controlling the degree of azidation.
Abstract: [Cu(dap)2]Cl effectively catalyzes azide addition from the Zhdankin reagent to styrene-type double bonds, and subsequent addition of a third component to the benzylic position. In the presence of light, a photoredox cycle is implicated with polar components such as methanol or bromide adding to a benzylic cation. In the absence of light, by contrast, double azidation takes place to give diazides. Therefore, regioselective double functionalization can be achieved in good to excellent yields, with a switch between light and dark controlling the degree of azidation.
157 citations
TL;DR: Introduction of Ag(i) ions into a sulfonic acid functionalized MOF significantly enhances its interactions with olefin double bonds, leading to its much higher selectivities for the separation of C2H4-C2H6 and C3H6-C3H8 at room temperature over the original (Cr)-MIL-101-SO3H and other adsorbents at roomTemperature.
151 citations
TL;DR: In this paper, a catalyst-free dynamic reversible exchange of aromatic Schiff base bonds is enabled at room temperature, and the exchange mechanism is studied by model compounds, and free radical intermediates are found to be involved in the non-equilibrium stage of the exchange reaction.
Abstract: The present work reveals that catalyst-free dynamic reversible exchange of aromatic Schiff base bonds is enabled at room temperature. Attachment of aryl groups to both nitrogen and carbon atoms of carbon–nitrogen double bonds is a critical structural factor that contributes to the dynamic characteristics and complete reaction between aromatic aldehyde and aromatic amine. The exchange mechanism is studied by model compounds, and free radical intermediates are found to be involved in the non-equilibrium stage of the exchange reaction. By taking advantage of the dynamic equilibrium of aromatic Schiff base bonds, infusible and insoluble crosslinked polyacrylate is self-healed and reprocessed through rearrangement of macromolecular networks. The reprocessed polymer is still self-healable. Either the self-healing or reprocessing is completed in air without heating. Considering that Schiff base polymers have shown diverse properties and stimulus–response behaviors, activation of the dynamic exchange of the inherent Schiff base bonds would result in a series of novel functionalities. More interestingly, traditional crosslinked polymers might thus be provided with a facile way of being smarter.
148 citations
TL;DR: A Rh(III) -catalyzed C-H activation/cyclative capture approach, involving a nucleophilic addition of C(sp(3) )-Rh species to polarized double bonds is reported, becoming the first intermolecular catalytic method to directly access 1-aminoindolines with a broad substituent scope under mild conditions.
Abstract: A Rh(III) -catalyzed C-H activation/cyclative capture approach, involving a nucleophilic addition of C(sp(3) )-Rh species to polarized double bonds is reported. This constitutes the first intermolecular catalytic method to directly access 1-aminoindolines with a broad substituent scope under mild conditions.
133 citations
TL;DR: A C-C bond-forming conjugate reaction was successfully applied to the enantioselective dearomatization of β-naphthols to form a C(sp2)-C(sp3) bond by using propargylic ketones as reactive partners.
Abstract: A C C bond-forming conjugate reaction was successfully applied to the enantioselective dearomatization of β-naphthols. A C(sp2) C(sp3) bond is formed by using propargylic ketones as reactive partners. Good to excellent Z / E ratios and ee values were obtained by employing an in situ generated magnesium catalyst. Further transformations of the Z -configured C C double bond in the products were achieved under mild reaction conditions. Moreover, the stereocontrolling element of this magnesium-catalyzed dearomatization reaction was explored by computational chemistry.
89 citations
TL;DR: In this article, a model complex of cyclotron resonance (FT-ICR) mass spectrometry (MS) was used to study the reaction of [FeIII(TPFPP)]+ with iodosylbenzene as a terminal oxidant, which leads to the production of ions corresponding to [FeIV(O)(TPP+˙)]+ for the first time.
Abstract: Cytochrome P450 enzymes are heme based monoxygenases that catalyse a range of oxygen atom transfer reactions with various substrates, including aliphatic and aromatic hydroxylation as well as epoxidation reactions. The active species is short-lived and difficult to trap and characterize experimentally, moreover, it reacts in a regioselective manner with substrates leading to aliphatic hydroxylation and epoxidation products, but the origin of this regioselectivity is poorly understood. We have synthesized a model complex and studied it with low-pressure Fourier transform-ion cyclotron resonance (FT-ICR) mass spectrometry (MS). A novel approach was devised using the reaction of [FeIII(TPFPP)]+ (TPFPP = meso-tetrakis(pentafluorophenyl)porphinato dianion) with iodosylbenzene as a terminal oxidant which leads to the production of ions corresponding to [FeIV(O)(TPFPP+˙)]+. This species was isolated in the gas-phase and studied in its reactivity with a variety of olefins. Product patterns and rate constants under Ideal Gas conditions were determined by FT-ICR MS. All substrates react with [FeIV(O)(TPFPP+˙)]+ by a more or less efficient oxygen atom transfer process. In addition, substrates with low ionization energies react by a charge-transfer channel, which enabled us to determine the electron affinity of [FeIV(O)(TPFPP+˙)]+ for the first time. Interestingly, no hydrogen atom abstraction pathways are observed for the reaction of [FeIV(O)(TPFPP+˙)]+ with prototypical olefins such as propene, cyclohexene and cyclohexadiene and also no kinetic isotope effect in the reaction rate is found, which suggests that the competition between epoxidation and hydroxylation – in the gas-phase – is in favour of substrate epoxidation. This notion further implies that P450 enzymes will need to adapt their substrate binding pocket, in order to enable favourable aliphatic hydroxylation over double bond epoxidation pathways. The MS studies yield a large test-set of experimental reaction rates of iron(IV)–oxo porphyrin cation radical complexes, so far unprecedented in the gas-phase, providing a benchmark for calibration studies using computational techniques. Preliminary computational results presented here confirm the observed trends excellently and rationalize the reactivities within the framework of thermochemical considerations and valence bond schemes.
88 citations
TL;DR: The second double bond of acrylic anhydride rapidly inserts intramolecularly to regio- and stereoselectively form a cyclic repeat unit and a primary alkyl favorable for chain growth that results in significantly enhanced copolymer molecular weights vs monofunctional acrylate monomers.
Abstract: In catalytic copolymerization, undesired chain transfer after incorporation of a polar vinyl monomer is a fundamental problem. We show an approach to overcome this problem by a fast consecutive insertion. The second double bond of acrylic anhydride rapidly inserts intramolecularly to regio- and stereoselectively form a cyclic repeat unit and a primary alkyl favorable for chain growth (>96%). This results in significantly enhanced copolymer molecular weights vs monofunctional acrylate monomers.
85 citations
TL;DR: In this paper, a ReaxFF force field for Fe/Cr/O/S was developed against data from quantum mechanical (QM) calculations to simulate the catalyzed oxidation reaction of butane at 1600 K.
Abstract: We developed a ReaxFF force field for Fe/Cr/O/S, which is parametrized against data from quantum mechanical (QM) calculations. Using this force field, we studied the Cr-oxide catalyzed oxidation reaction of butane at 1600 K. Our simulation results demonstrate that the active oxygen species on the oxide surface play an important role in the conversion of butane. Dehydrogenation of butane, which is found to be catalyzed by oxygen species on the oxide surface, initiates the reaction and generates butane radicals and surface OH groups. The radical intermediates are associated with the oxygen atoms to form C–O bonds or make double bonds when neighboring carbon atoms are dehydrogenated, forming light alkenes. On the clean Cr-oxide, the major oxidation product is CH2O. The presence of iron pyrite (FeS2), a common inorganic component in coal-derived fuels and a major slagging component, on Cr-oxide accelerates the complete oxidation of butane forming CO2 and CO. Surface reconstruction by iron pyrite is probably r...
TL;DR: Mechanistic studies elucidated the sequence of hydrosilylation in this multiple reduction cascade: 1,2- or 1,4-hydrosilylated as an initial step depending on the substituent position, followed by selective hydrosallylation of enamine double bonds eventually affording β-silylated azacyclic compounds.
Abstract: Tris(pentafluorophenyl)borane-catalyzed silylative reduction of pyridines has been developed giving rise to the formation of sp(3) C-Si bonds selectively beta to the nitrogen atom of azacyclic products. Depending on the position and nature of pyridine substituents, structurally diverse azacycles are obtained with high selectivity under the borane catalysis. Mechanistic studies elucidated the sequence of hydrosilylation in this multiple reduction cascade: 1,2- or 1,4-hydrosilylation as an initial step depending on the substituent position, followed by selective hydrosilylation of enamine double bonds eventually affording β-silylated azacyclic compounds.
TL;DR: This method proceeds via the C(sp(3))-H oxidative coupling with the C-C double bond and 1,2-aryl-migration, and represents a new access to acyclic molecules through metal-free oxidative alkene 1, 2-alkylarylation.
TL;DR: An unprecedented approach to N-trifluoromethylations of electron-rich nucleophilic sites following a radical pathway is reported, providing previously unreported products with satisfying functionality tolerance in moderate to good yields.
TL;DR: X-ray and computational structural analyses show a "transition-metal-like" cis-bis(imido) geometry and polarized Th═N bonds with twice the Wiberg bond order of the formally single Th-N bond in the same molecule.
Abstract: Molecules containing actinide–nitrogen multiple bonds are of current interest as simple models for new actinide nitride nuclear fuels, and for their potential for the catalytic activation of inert hydrocarbon C–H bonds. Complexes with up to three uranium–nitrogen double bonds are now being widely studied, yet those with one thorium–nitrogen double bond are rare, and those with two are unknown. A new, simple mono(imido) thorium complex and the first bis(imido) thorium complex, K[Th(═NAr)N″3] and K2[Th(═NAr)2N″2], are readily made from insertion reactions (Ar = aryl, N″ = N(SiMe3)2) into the Th–C bond of the cyclometalated thorium amides [ThN″2(N(SiMe3)(SiMe2CH2))] and K[ThN″(N(SiMe3)(SiMe2CH2))2]. X-ray and computational structural analyses show a “transition-metal-like” cis-bis(imido) geometry and polarized Th═N bonds with twice the Wiberg bond order of the formally single Th–N bond in the same molecule.
TL;DR: It is demonstrated that (LDipN)AlTe(LEt)2 comprises the elusive Al=Te double bond in the form of an N-heterocyclic carbene-stabilized species.
Abstract: Aluminum chalcogenides are mostly encountered in the form of bulk aluminum oxides that are structurally diverse but typically consist of networks with high lattice energy in which the chalcogen atoms bridge the metal centres. This makes their molecular congeners difficult to synthesize because of a pronounced tendency for oligomerization. Here we describe the isolation of the monotopic aluminum chalcogenide (L(Dip)N)AlTe(L(Et))2 (L(Dip)=1,3-(2,6-diisopropylphenyl)-imidazolin-2-imine, L(Et)=1,3-diethyl-4,5-dimethyl-imidazolin-2-ylidene). Unique features of (L(Dip)N)AlTe(L(Et))2 are the terminal position of the tellurium atom, the shortest aluminum-tellurium distance hitherto reported for a molecular complex and the highest bond order reported for an interaction between these elements, to the best of our knowledge. At elevated temperature (L(Dip)N)AlTe(L(Et))2 equilibrates with dimeric {(L(Dip)N)AlTe(L(Et))}2 in which the chalcogen atoms assume their common role as bridges between the metal centres. These findings demonstrate that (L(Dip)N)AlTe(L(Et))2 comprises the elusive Al=Te double bond in the form of an N-heterocyclic carbene-stabilized species.
TL;DR: In this article, the authors measured the sooting tendencies of twenty C4 to C7 unsaturated esters and reported their Yield Sooting Indices (YSI) and found that unsaturated methyl esters had larger increases in YSI compared to their parent saturated esters than unsaturated ethyl or propyl esters.
TL;DR: The first catalytic enantioselective nucleophilic borylation of a C═O double bond has been achieved and the products could be readily converted to the corresponding functionalized chiral alcohol derivatives through stereospecific C-C bond forming reactions involving the stereogenic C-B bond.
Abstract: The first catalytic enantioselective nucleophilic borylation of a C═O double bond has been achieved. A series of aldehydes reacted with a diboron reagent in the presence of a copper(I)/DTBM-SEGPHOS complex catalyst using MeOH as a proton source to give the corresponding optically active α-alkoxyorganoboronate esters with excellent enantioselectivities. Furthermore, the products could be readily converted to the corresponding functionalized chiral alcohol derivatives through stereospecific C–C bond forming reactions involving the stereogenic C–B bond.
TL;DR: In this article, the authors evaluate the selectivity and applicability of different catalytic approaches for water addition reactions: homogeneous, heterogeneous and bio-catalytic, and discuss how to speed up water addition and even make it selective.
TL;DR: In this article, the effect of temperature, pressure, and solvent on 1-butene oligomerization was studied over H-ferrierite, and the reaction product mixture revealed that H-Ferrierite promoted double bond isomerization and skeletal isomerisation.
TL;DR: The reactivity of the 2-phosphaethynolate anion (PCO−) towards a cyclic trisilene (cSi3(Tip)4) is reported, which results in the net activation of the P=C and Si=Si multiple bonds of the precursors affording a heteroatomic bicyclo.
Abstract: The reactivity of the 2-phosphaethynolate anion (PCO−) towards a cyclic trisilene (cSi3(Tip)4) is reported. The result is the net activation of the P=C and Si=Si multiple bonds of the precursors affording a heteroatomic bicyclo[1.1.1]pentan-2-one analogue ([P(CO)Si3(Tip)4]−; 1). This reaction can be interpreted as the formal addition of a phosphide and a carbonyl across the Si=Si double bond. Photolytic decarbonylation of 1 results in the incorporation of the phosphide vertex into the cyclotrisilene scaffold, yielding a congener of the cyclobutene anion with considerable allylic character.
TL;DR: In this paper, the boron-boron triple bond character of the compound B2(NHCMe)2 has been investigated and a thorough examination of the electronic structure with an energy decomposition analysis has been carried out.
Abstract: Quantum chemical calculations of the compound B2(NHCMe)2 and a thorough examination of the electronic structure with an energy decomposition analysis provide strong evidence for the appearance of boron–boron triple bond character. This holds for the model compound and for the isolated diboryne B2(NHCR)2 of Braunschweig which has an even slightly shorter B–B bond. The bonding situation in the molecule is best described in terms of NHCMe→B2←NHCMe donor–acceptor interactions and concomitant π-backdonation NHCMe←B2→NHCMe which weakens the B–B bond, but the essential features of a triple bond are preserved. An appropriate formula which depicts both interactions is the sketch NHCMe⇄BB⇄NHCMe. Calculations of the stretching force constants FBB which take molecules that have genuine single, double and triple bonds as references suggest that the effective bond order of B2(NHCMe)2 has the value of 2.34. The suggestion by Koppe and Schnockel that the strength of the boron–boron bond in B2(NHCH)2 is only between a single and a double bond is repudiated. It misleadingly takes the force constant FBB of OBBO as the reference value for a B–B single bond which ignores π bonding contributions. The alleged similarity between the B–O bonds in OBBO and the B–C bonds in B2(NHCMe)2 is a mistaken application of the principle of isolable relationship.
TL;DR: An efficient two-step synthesis of the first NHC-stabilized disilavinylidene (Z)-(SIdipp)Si=Si(Br)Tbb (2) (2; SIdipp=C[N(C6H3-2,6-iPr2)CH2]2, Tbb=C 6H2- 2,6-[CH(SiMe3)2)2-4-tBu, NHC=
Abstract: An efficient two-step synthesis of the first NHC-stabilized disilavinylidene (Z)-(SIdipp)SiSi(Br)Tbb (2; SIdipp=C[N(C6H3-2,6-iPr2)CH2]2, Tbb=C6H2-2,6-[CH(SiMe3)2]2-4-tBu, NHC=N-heterocyclic carbene) is reported. The first step of the procedure involved a 2:1 reaction of SiBr2(SIdipp) with the 1,2-dibromodisilene (E)-Tbb(Br)SiSi(Br)Tbb at 100 °C, which afforded selectively an unprecedented NHC-stabilized bromo(silyl)silylene, namely SiBr(SiBr2Tbb)(SIdipp) (1). Alternatively, compound 1 could be obtained from the 2:1 reaction of SiBr2(SIdipp) with LiTbb at low temperature. 1 was then selectively reduced with C8K to give the NHC-stabilized disilavinylidene 2. Both low-valent silicon compounds were comprehensively characterized by X-ray diffraction analysis, multinuclear NMR spectroscopy, and elemental analyses. Additionally, the electronic structure of 2 was studied by various quantum-chemical methods.
TL;DR: Metric and DFT (Density Functional Theory) evidence support that 2a and 2b possess strong Si═O double bond character, while 3 and 4 contain more ionic terminal Si-O bonds.
Abstract: The silicon analogues of an acylium ion, namely, sila-acylium ions 2a and 2b [RSi(O)(NHC)2]Cl stabilized by two N-heterocyclic carbenes (NHC = 1,3,4,5-tetramethylimidazol-2-ylidene), and having chloride as a countercation were successfully synthesized by the reduction of CO2 using the donor stabilized silyliumylidene cations 1a and 1b [RSi(NHC)2]Cl (1a, 2a; R = m-Ter = 2,6-Mes2C6H3, Mes = 2,4,6-Me3C6H2 and 1b, 2b; R = Tipp = 2,4,6-iPr3C6H2). Structurally, compound 2a features a four coordinate silicon center together with a double bond between silicon and oxygen atoms. The reaction of sila-acylium ions 2a and 2b with water afforded different products which depend on the bulkiness of aryl substituents. Although the exposure of 2a to H2O afforded a stable silicon analogue of carboxylate anion as a dimer form, [m-TerSi(O)O]22–·2[NHC–H]+ (3), the same reaction with the less bulkier triisopropylphenyl substituted sila-acylium ion 2b afforded cyclotetrasiloxanediol dianion [{TippSi(O)}4{(O)OH}2]2–·2[NHC–H]+ (4)...
TL;DR: Complexes 2, 3, 5 and 7 proved to be efficient precatalysts for the intermolecular hydrophosphination of styrene, 4-vinylpyridine, and 1-nonene with PhPH2 and Ph2PH as well as hydroamination of Styrene and pyrrolidine.
Abstract: Metallacyclic neutral and ionic yttrium alkyl complexes coordinated by a dianionic ene-diamido ligand ([2,6-iPr2C6H3NC(Me)C(Me)NC6H3iPr2-2,6] = L1) [L1]Y(CH2SiMe3)(THF)2 (2), {[L1]Y(CH2SiMe3)2}−{Li(THF)4}+ (3), [L1]Y(OEt2)(μ-Me)2Li(TMEDA) (4) were synthesized using a salt-metathesis approach starting from the related chloro complex [L1]Y(THF)2(μ-Cl)2Li(THF)2 (1) in 70, 85 and 72% yields respectively. The reactions of 2 with H2 or PhSiH3 afford the dimeric hydride {[L1]Y(THF)(μ-H)}2(μ-THF) (5) containing two μ-bridging hydrido and one μ-bridging THF ligands (91 and 85% yields). The X-ray studies of complexes 2, 3 and 5 revealed η2-coordination of the CC fragment of an ene-diamido ligand to a Y cation. DFT calculations were carried out to give an insight into the metal–ligand bonding and especially the interaction between the metal and the ene-diamido ligand. The observed bonding of the ene-diamido fragment is found to reflect the acidity of the metal center in the complex that is partially overcome by a better donation from the double bond (better overlap with an empty d orbital at the yttrium center). The treatment of complex 4 with DME resulted in the C–O bond cleavage of DME and afforded a three nuclear methoxide oxide complex [{[L1]Y}3(μ2-OMe)3(μ3-O)]2−[Li(DME)3]+2 (6). Complexes 2, 3, 5 and 7 proved to be efficient precatalysts for the intermolecular hydrophosphination of styrene, 4-vinylpyridine, and 1-nonene with PhPH2 and Ph2PH as well as hydroamination of styrene and pyrrolidine.
TL;DR: The first Fe-facilitated decarboxylative cross-coupling reaction between α-oxocarboxylic acids and acrylic acids in aqueous solution has been developed, providing an efficient and expeditious approach to an important class of α,β-unsaturated carbonyls frequently found in bioactive compounds.
Abstract: The first Fe-facilitated decarboxylative cross-coupling reaction between α-oxocarboxylic acids and acrylic acids in aqueous solution has been developed. This transformation is characterized by its wide substrate scope and good functional group compatibility utilizing inexpensive and easily accessible reagents, thus providing an efficient and expeditious approach to an important class of α,β-unsaturated carbonyls frequently found in bioactive compounds. The synthetic potential of the coupled products is also demonstrated in subsequent functionalization reactions. Preliminary mechanism studies suggest that a free radical pathway is involved in this process: the generation of an acyl radical from α-oxocarboxylic acid via the excision of carbon dioxide followed by the addition of an acyl radical to the α-position of the double bond in acrylic acid then delivers the α,β-unsaturated carbonyl adduct through the extrusion of another carbon dioxide.
TL;DR: In this article, a careful analysis in terms of bond enthalpies, counting double bonds as two bonds to keep the total number of bonds unchanged, gives the heat of combustion close to −418 kJ/mol (i.e., −100 kcal/mol) for each mole of O2, in good agreement (±3.1%) with data for >500 organic compounds.
Abstract: The strongly exothermic nature of reactions between molecular oxygen and all organic molecules as well as many other substances is explained in simple, general terms. The double bond in O2 is much weaker than other double bonds or pairs of single bonds, and therefore the formation of the stronger bonds in CO2 and H2O results in the release of energy, which is given off as heat or increases thermal motion. This explains why fire is hot regardless of fuel composition. The bond energies in the fuel play only a minor role; for example, the total bond energy of CH4 is nearly the same as that of CO2. A careful analysis in terms of bond enthalpies, counting double bonds as two bonds to keep the total number of bonds unchanged, gives the heat of combustion close to −418 kJ/mol (i.e., −100 kcal/mol) for each mole of O2, in good agreement (±3.1%) with data for >500 organic compounds; the heat of condensation of H2O, −44 kJ/mol, is also included in the analysis. For 268 molecules with ≥ 8 carbon atoms, the standard ...
TL;DR: A copper-catalyzed oxyalkylation of allylic alcohols using nonactivated alkyl nitriles as reaction partners was developed and provided an efficient route to functionalized tri- and tetrasubstituted epoxides with moderate to excellent diastereoselectivity.
TL;DR: The thermal degradation of 2-alkenals and 2,4-alkadienals is described in an attempt to both clarify the stability of aldehydes and determine new compounds that might also play a role in nucleophile/aldehyde reactions.
TL;DR: In this article, the CC double bond cleavage of enaminones has been realized under ambient conditions through visible-light catalysis in the presence of Rose Bengal, which leads to the synthesis of a class of 1,2-diketones without using any metal catalyst.
Abstract: The CC double bond cleavage of enaminones has been realized under ambient conditions through visible-light catalysis in the presence of Rose Bengal, which leads to the synthesis of a class of 1,2-diketones without using any metal catalyst. In addition, the one-pot synthesis of quinoxalines has also been achieved under identical photocatalytic conditions by making use of the in situ generated 1,2-diketones as intermediates.