72221-03-5Relevant academic research and scientific papers
SYSTEMS AND METHODS FOR REGIOSELECTIVE CARBONYLATION OF 2,2-DISUBSTITUTED EPOXIDES
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Paragraph 0146; 0151; 0153, (2020/06/05)
Provided are methods of carbonylating cyclic substrates to produce carbonyl ated cyclic products. The cyclic substrates may be 2, 2-di substituted epoxides and the cyclic products may be β,β-di substituted lactones. The method may be carried out by forming and pressurizing a reaction mixture of the cyclic substrate, a solvent, carbon monoxide, and a [LA+][CO(CO)4-] catalyst, where [LA+] is a Lewis acid capable of coordinating to the cyclic substrate. The method may proceed with a regioselectivity of 90:10 or greater. The resulting carbonylated cyclic products may be converted to ketone aldol products that retain the stereochemistry and enantiomeric ratio of the carbonyl ated cyclic products.
Regioselective Carbonylation of 2,2-Disubstituted Epoxides: An Alternative Route to Ketone-Based Aldol Products
Hubbell, Aran K.,Lapointe, Anne M.,Lamb, Jessica R.,Coates, Geoffrey W.
supporting information, p. 2474 - 2480 (2019/02/14)
We report the regioselective carbonylation of 2,2-disubstituted epoxides to β,β-disubstituted β-lactones. Mechanistic studies revealed epoxide ring-opening as the turnover limiting step, an insight that facilitated the development of improved reaction conditions using weakly donating, ethereal solvents. A wide range of epoxides can be carbonylated to β-lactones, which are subsequently ring-opened to produce ketone-based aldol adducts, providing an alternative to the Mukaiyama aldol reaction. Enantiopure epoxides were demonstrated to undergo the carbonylation/ring-opening process with retention of stereochemistry to form enantiopure β-hydroxy esters.
A comprehensive test set of epoxidation rate constants for iron(IV)-oxo porphyrin cation radical complexes
Sainna, Mala A.,Kumar, Suresh,Kumar, Devesh,Fornarini, Simonetta,Crestoni, Maria Elisa,De Visser, Sam P.
, p. 1516 - 1529 (2015/03/04)
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+a?￠)]+. 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+a?￠)]+ 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+a?￠)]+ for the first time. Interestingly, no hydrogen atom abstraction pathways are observed for the reaction of [FeIV(O)(TPFPP+a?￠)]+ 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.
Experimental investigation of the low temperature oxidation of the five isomers of hexane
Wang, Zhandong,Herbinet, Olivier,Cheng, Zhanjun,Husson, Benoit,Fournet, Rene,Qi, Fei,Battin-Leclerc, Frederique
, p. 5573 - 5594 (2014/08/18)
The low-temperature oxidation of the five hexane isomers (n-hexane, 2-methyl-pentane, 3-methyl-pentane, 2,2-dimethylbutane, and 2,3-dimethylbutane) was studied in a jet-stirred reactor (JSR) at atmospheric pressure under stoichiometric conditions between 550 and 1000 K. The evolution of reactant and product mole fraction profiles were recorded as a function of the temperature using two analytical methods: gas chromatography and synchrotron vacuum ultraviolet photoionization mass spectrometry (SVUV-PIMS). Experimental data obtained with both methods were in good agreement for the five fuels. These data were used to compare the reactivity and the nature of the reaction products and their distribution. At low temperature (below 800 K), n-hexane was the most reactive isomer. The two methyl-pentane isomers have about the same reactivity, which was lower than that of n-hexane. 2,2-Dimethylbutane was less reactive than the two methyl-pentane isomers, and 2,3-dimethylbutane was the least reactive isomer. These observations are in good agreement with research octane numbers given in the literature. Cyclic ethers with rings including 3, 4, 5, and 6 atoms have been identified and quantified for the five fuels. While the cyclic ether distribution was notably more detailed than in other literature of JSR studies of branched alkane oxidation, some oxiranes were missing among the cyclic ethers expected from methyl-pentanes. Using SVUV-PIMS, the formation of C 2-C3 monocarboxylic acids, ketohydroperoxides, and species with two carbonyl groups have also been observed, supporting their possible formation from branched reactants. This is in line with what was previously experimentally demonstrated from linear fuels. Possible structures and ways of decomposition of the most probable ketohydroperoxides were discussed. Above 800 K, all five isomers have about the same reactivity, with a larger formation from branched alkanes of some unsaturated species, such as allene and propyne, which are known to be soot precursors.
Process for preparing epoxides from carbonyl compounds using sulphonium or sulphoxonium ylides and intermediates useful therein
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, (2008/06/13)
A process for transforming a carbonyl compound into its corresponding epoxide, which comprises contacting the carbonyl compound with either trimethylsulphonium hydrogen sulphate and/or bis(trimethylsulphonium) sulphate or trimethylsulphoxonium hydrogen sulphate and/or bis(trimethylsulphoxonium) sulphate, in the presence of a base.
Oxo Complexes of Ruthenium with N,N'-Donors as Oxidation Catalysts for Alkenes, Alkanes and Alcohols, and their Osmium Analogues
Bailey, Alan J.,Griffith, William P.,Savage, Paul D.
, p. 3537 - 3542 (2007/10/03)
Catalysis of the epoxidation of alkenes and oxidation of alkanes and alcohols by a variety of bis-bipy (2,2'-bipyridyl) and bis-phen (1,10-phenanthroline) ruthenium complexes with NaIO4 or IO4 as co-oxidants has been investigated together with similar oxidations with >*1.5H2O.The new complexes > and > (L-L = bipy, phen or 2,2'-dipyridylamine) have been prepared and characterised.
A New Epoxidation Catalyst: the Reactivity and X-Ray Crystal Structure of >*1.5H2O (bipy = 2,2'-bipyridine)
Bailey, Alan J.,Griffith, William P.,White, Andrew J. P.,Williams, David J.
, p. 1833 - 1834 (2007/10/02)
The crystal structure of >*1.5H2O 1 is reported: with NaIO4 or NBun4IO4 as cooxidant it is an efficient catalyst for alkene epoxidations under mild conditions; it also oxidises primary alcohols to aldehydes and secondary alcohols to ketones.
Simple, Inexpensive Synthesis of Oxiranes from Carbonyl Compounds. Generation of Sulfonium Ylides from the Ternary System Methanol-Sulfuric Acid-Dimethyl Sulfide
Forrester, Julie,Jones, Ray V. H,Preston, Peter N.,Simpson, Elisabeth S. C.
, p. 1937 - 1938 (2007/10/02)
Reaction conditions are described for the transformation of benzaldehyde and series of ketones into epoxides, in situ, in the ternary system: methanol-sulfuric acid-dimethyl sulfide.
KINETIC ANALYSIS OF ALKANE POLYCHLORINATION WITH MOLECULAR CHLORINE. CHLORINE ATOM/MONOCHLORIDE GEMINATE PAIRS AND THE EFFECT OF REACTIVE 'CAGE WALLS' ON THE COMPETITION BETWEEN MONOCHLORIDE ROTATION AND CHLORINE ATOM ESCAPE.
Raner,Lusztyk,Ingold
, p. 3519 - 3524 (2007/10/02)
The free-radical chlorination of alkanes produces polychlorides even at low conversions. These are formed by reaction of chlorine atom/monochloride (or dichloride) geminate pairs. This process has been studied in detail in various solvent systems, and a kinetic scheme has been proposed. Deviations from this scheme have been rationalized as being due to competition between monochloride rotation and reaction of the chlorine atom with reactive molecules in the 'cage walls' surrounding the chlorine atom/chloride geminate pair. Analysis of the dichloride products supports the suggestion that monochloride rotation is not completely 'free' within the lifetime of the geminate pair.
Photoinduced Nitrene, Carbene, and Atomic Oxygen Transfer Reactions Starting from the Corresponding Pyridinium N-, C-, and O-Ylides
Strub, Henri,Strehler, Christiane,Streith, Jacques
, p. 355 - 364 (2007/10/02)
Ultraviolet irradiation of the pyridinium ylides 1, 2, and 3 led to fragmentation of the exocyclic polar bonds, as well as to skeletal rearrangements.The photoinduced fragmentation processes gave the corresponding pyridines and highly reactive intermediates, i. e. ethoxycarbonylnitrene, dicyanocarbene and atomic oxygen (oxene), respectively.Trapping of the reactive intermediates by alkanes and alkenes permitted the determination of their spin multiplicity.Ethoxycarbonylnitrene was in its triplet ground state at the moment of its formation.Dicyanocarbene occurred as a mixture of singlet and triplet, as determined by dilution experiments with variable amounts of alkenes.As to atomic oxygen, all collected data point to its formation in solution in its triplet ground state.
