55577-88-3Relevant articles and documents
A five deuterium generation jasmonic, its salt, wherein the intermediate, preparation method and use
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Paragraph 0137; 0138, (2017/04/03)
The invention discloses an 11,11,12,12,12-pentadeuterojasmonic acid disclosed as Formula 11, a salt and intermediate, and a preparation method and application thereof. The preparation method of the pentadeuterojasmonic acid comprises the following steps:
Phosphane-catalyzed [3+2] annulation of allenoates with aldehydes: A simple and efficient synthesis of 2-alkylidenetetrahydrofurans
Xu, Silong,Zhou, Lili,Ma, Renqin,Song, Haibin,He, Zhengjie
supporting information; scheme or table, p. 8698 - 8702 (2010/03/25)
A phosphane-catalyzed [3 +2] annulation of γ-methyl allenoates with aromatic aldehydes has been reported. This annulation provides a convergent and efficient synthesis of 2-alkylidenetetrahydrofurans, which are versatile synthetic building blocks for a vast array of 5-membered oxygenated heterocycle derivatives. The EIZ isomers of 2-(ethoxycarbonylmethylene) tetrahydrofurans, was separated by column chromatography on silica gel and their structural assignments were confirmed by H and C NMR spectroscopy data and X-ray crystallographic analysis. The nature of the substituent, as well as the reaction conditions, has a significant influence on the reactivity patterns of γ-substituted allenoates with aldehydes. The phosphorus ylide, generated from the phosphonium dienolate 8 by an overall 1,4-hydrogen shift, is believed to be the key intermediate responsible for the [3 + 2] annulation and other transformations of γ-methyl allenoates with aldehydes.
An improved procedure for the synthesis of labelled fatty acids utilizing diethyl malonate
Kasumov, Takhar,Brunengraber, Henri
, p. 171 - 176 (2007/10/03)
An improved procedure for the preparation and purification of labeled fatty acids by malonic ester synthesis has been developed. This method uses the different hydrolysis rates of the monoalkylmalonic ester intermediate and its dialkylmalonic ester side p
A convenient and inexpensive synthesis of labelled methylmalonic and propionic acids: Application to the synthesis of methyl-d3-malonic and of propionic-3,3,3-d3 acids
Allevi, Pietro,Longo, Alessandra,Anastasia, Mario
, p. 1085 - 1091 (2007/10/03)
A synthetic route for obtaining highly pure methylmalonic and propionic acids labelled at the methyl groups is validated by the preparation of methyl-d3-malonic and propionic-3,3,3-d3 acids. The synthesis involves the alkylation of the diethyl allylmalonate with iodomethane-d3, deallylation of the resulting diethyl allylmethyl-d3-malonate by treatment with (η2-propene)Ti(O-i-Pr)2 and hydrolysis. Decarboxylation of the obtained methyl-d3-malonic acid affords propionic-3,3,3-d3 acid.
Mechanism of Propene and Water Elimination from the Oxonium Ion CH3CH=O+CH2CH2CH3
Bowen, Richard D.,Suh, Dennis,Terlouw, Johan K.
, p. 119 - 130 (2007/10/02)
The site-selectivity in the hydrogen transfer step(s) which result in propene and water loss from metastable oxonium ions generated as CH3CH=O+CH2CH2CH3 have been investigated by deuterium-labelling experiments.Propene elimination proceeds predominantly by transfer of a hydrogen atom from the initial propyl substituent to oxygen.However, the site-selectivity for this process is inconsistent with β-hydrogen transfer involving a four-centre transition state.The preference for apparent α- or γ-hydrogen transfer is interpreted by a mechanism in which the initial propyl cation accessible by stretching the appropriate bond in CH3CH=O+CH2CH2CH3 isomerizes unidirectionally to an isopropyl cation, which then undergoes proton abstraction from either methyl group +CH2CH2CH3 CH3CH=O---+CH2CH2CH3 +CH(CH3)2> + CH3CH=CH2>>.This mechanism involving ion-neutral complexes can be elaborated to accommodate the minor contribution of expulsion of propene containing hydrogen atoms originally located on the two-carbon chain.Water elimination resembles propene loss insofar as there is a strong preference for selecting the hydrogen atoms from the α- and γ-positions of the initial propyl group.The bulk of water loss is explicable by an extension of the mechanism for propene loss, with the result that one hydrogen atom is eventually transferred to oxygen from each of the two methyl groups in the complex +CH(CH3)2>.This site-selectivity is strikingly different from that (almost random participation of the seven hydrogen atoms of the propyl substituent) encountered in the corresponding fragmentation of the lower homologue CH2=O+CH2CH2CH3.This contrast is explained in terms of the differences in the relative energetics and associated rates of the cation rearrangement and hydrogen transfer steps.
Unimolecular Reactions of Isolated Organic Ions: the Chemistry of the Oxonium Ions CH3CH2CH2CH2(+)O=CH2 and CH3CH2CH2CH=O(+)CH3
Bowen, Richard D.,Derrick, Peter J.
, p. 1197 - 1209 (2007/10/02)
The reactions of the metastable oxonium ions CH3CH2CH2CH2(+)O=CH2 and CH3CH2CH2CH=O(+)CH3 are reported and discussed.Both these isomers of C5H11O(+) expel predominantly CH2O (75 - 90percent of the metastable ion current), a moderate amount of C3H6 (5-15percent), a minor amount of CH3OH (2-8percent) and a very small proportion of H2O (0.5-3percent).All these processes give rise to Gaussian metastable peaks.The kinetic energy releases associated with fragmentation of these oxonium ions are similar, but slightly larger for dissociation of CH3CH2CH2CH=O(+)CH3.The behaviour of labelled analogues confirms that the reactions of CH3CH2CH2CH2(+)O=CH2 and CH3CH2CH2CH=O(+)CH3 are closely related, but subtly different.Elimination of CH2O and C3H6 is intelligible by means of mechanisms involving CH3CH(+)CH2CH2OCH3.This open-chain cation is accessible to CH3CH2CH2CH2(+)O=CH2 by a 1,5-H shift and to CH3CH2CH2CH=O(+)CH3 by two consecutive 1,2-H shifts (or, possibly, a direct 1,3-H shift).The rates of these 1,2-, 1,3- and 1,5-H shifts are compared with one another and also with the rates of CH2O and C3H6 loss from each of the two oxonium ions.The 1,5-H shift that converts CH3CH(+)CH2CH2OCH3 formed from CH3CH2CH2CH=O(+)CH3 into CH3CH2CH2CH2(+)O=CH2 prior to CH2O elimination is essentially unidirectional.In contrast, the corresponding step converting C5H11O(+) ions generated as CH3CH2CH2CH2(+)O=CH2 into CH3CH(+)CH2CH2OCH3 competes effectively with expulsion of CH2O and C3H6.The implications of the latter finding for the degree of concert in the hydrogen transfer and carbon-carbon bond fission steps in alkene losses from oxonium ions via routes that are formally isoelectronic with the retro 'ene' pericyclic process are emphasized.
Unimolecular Reactions of Isolated Organic Ions: Reactions of the Immonium Ions CH2=N+(CH3)CH(CH3)2, CH2=N+(CH3)CH2CH2CH3 and CH2=N+(CH2CH2CH3)2
Bowen, Richard D.,Colburn, Alex W.,Derrick, Peter J.
, p. 2363 - 2372 (2007/10/02)
The reactions of metastable CH2=N+(CH3)C3H7 immonium ions have been investigated by means of 2H-labelling experiments and kinetic energy release measurements.Loss of C3H6, with specific β-H transfer, is the sole channel for dissociation of CH2=N+(CH3)CH(CH3)2.This process gives rise to a Gaussian metastable peak.The isomeric ion, CH2=N+(CH3)CH2CH2CH3, also expels C3H6; however, both α-H and γ-H as well as β-H transfer occurs in this case, and the reaction proceeds with an increased kinetic energy release.The role of ion-neutral complexes in C3H6 loss from CH2=N+(CH3)C3H7 ions is discussed.In addition, CH2=N+(CH3)CH2CH2CH3 eliminates C2H4.This fragmentation yields a broad dish-topped metastable peak, corresponding to a very large kinetic energy release (T1/2 ca. 73 kJ mol-1), and it involves specific and unidirectional γ-H transfer.A potential energy profile summarising the reactions of CH2=N+(CH3)CH2CH2CH3 and CH2=N+(CH3)CH(CH3)2 is constructed.The mechanisms by which immonium ions of this general class eliminate C3H6 and C2H4 have been further probed by studying the behaviour of the higher homologue, CH2=N+(CH2CH2CH3)2.The mechanistic conclusions derived from this work are found to be in excellent qualitative agreement with those of previous studies.
Alkene Loss from Metastable Methyleneimmonium Ions: Unusual Inverse Secondary Isotope Effect in Ion-Neutral Complex Intermediate Fragmentations
Veith, Hans J.,Gross, Juergen H.
, p. 1097 - 1108 (2007/10/02)
The mechanism of propene elimination from metastable methyleneimmonium ions is discussed.The first field-free region fragmentations of complete sets of isotopically labelled methyleneimmonium ions (H2C=N+R1R2 : R1 = R2 = n-C3H7; R1 = R2 = i-C3H7; R1 = n-C3H7; R2 = C2H5; R1 = n-C3H7; R2 = CH3; R1 = n-C3H7; R2 = H) were used to support the mechanism presented.The relative amounts of H/D transferred are quantitatively correlated to two distinct mathematical concepts which allow information to be deduced about influences on reaction pathways that cannot be measured directly.Propene loss from the ions examined proceeds via ion-neutral complex intermediates.For the di-n-propyl species rate-determining and H/D distribution-determining steps are clearly distinct.Whereas the former corresponds to a 1,2-hydride shift in a 1-propyl cation coordinated to an imine moiety, the latter is equivalent to a proton transfer to the imine occurring from the 2-propyl cation generated by the previous step.For the diisopropyl-substituted ions which directly form the 2-propyl cation-containing complex, the rate-determining hydride shift vanishes.The 2-propyl cation-containing complex can decompose directly or via an intermediate proton-bridged complex.Competition of these routes is not excluded by the experimental results.Assuming a 2:1:3 distribution, a preference for the α- and β-methylene of the initial n-propyl chain as the source of the hydrogen transferred is detected for n-propylimmonium ions containing a second alkyl chain R2.This preference shows a clear dependence on the steric influence of R2.During the transfer step isotopic substitution is found to affect the H/D distribution strongly.For the alternative route of McLafferty rearrangement leading to C2H4 loss, specific γ-H transfer is observed.
The Chemistry of Pyrrolic Compounds.LIX. The Oxidative Cyclization of Bilenes-b Substituted by Ethyl or Propyl Groups at a Terminal Site
Clezy, Peter S.,Ravi,B. N.,Thuc, Le van
, p. 419 - 432 (2007/10/02)
Oxidative cyclization of bilenes-b substituted with an ethyl or propyl group at one terminal site and a formyl equivalent at the other yields substantial quantities of the meso-ethyl- or meso-propyl-porphyrin. The origin of these meso-substituents has bee
Pseudo One-Step Cleavage of C-C Bonds in the Decomposition of Ionized Carboxyclic Acids. Radical Like Reactions in Mass Spectrometry
Weiske, Thomas,Schwarz, Helmut
, p. 323 - 347 (2007/10/02)
Metastable molecular ions of hexanoic acid (1) decompose unimolecularly to C2H5. and protonated methacrylic acid (5-H+)(92percent rel. abund.).Investigation of the mechanism reveals that 1) the branched cation radical 11 must be regarded as the essential intermediate in the course of the rearrangement/dissociation reaction and 2) the process commences with intramolecular hydrogen transfer from either C-3 or C-5 to the ionized carbonyl oxygen ("hidden" hydrogen migration).Hydrogen transfer from C-4, which would correspond to the well-known McLafferty rearrangement, is of no importance in the C2H5.-elimination from 1.The same conclusion applies for various alternative mechanisms, as for example a SRi type reaction, 1 -> 2-H+.The gas phase chemistry of the cation radical of 1, and in particular the hydrogen exchange processes between the methylene groups C-2/C-3 and C-5/C-6, is in surprisingly close correspondence to the chemistry of free alkyl radicals. - The syntheses of various 13C and 2H-labelled model compounds are described.
