83552-81-2Relevant academic research and scientific papers
Unexpected Structural Integrity of Gas Phase Isoquinoline Cations that Eliminate HCN
Baldwin, Michael A.,Gilmore, Jeremy,Mruzek, Margaret N.
, p. 127 - 129 (1983)
13C labellining has been used to study isoquinoline molecular ions undergoing breakdown by HCN elimination in a mass spectrometer.For otherwise stable ions caused to fragment by collisional activation, there is no skeletal rearrangement prior to HCN loss.Of the ions formed by 70 eV electron impact, 69percent of those which fragment in the ion source by HCN loss retain their structural integrity, as do 44percent of the metastable ions.Of the ions that eliminate HCN without prior arrangement, approximately two-thirds eliminate C-1 and one-third eliminate C-3.Critical energies are reported for the elimination of HCN from pyridine and isoquinoline molecular ions.
Investigation on the stoichiometry of carbon dioxide in isotope-exchange reactions with phenylacetic acids
Talbot, Alex,Sallustrau, Antoine,Goudet, Amélie,Taran, Frédéric,Audisio, Davide
supporting information, p. 171 - 176 (2021/08/10)
The functionalization of carbon dioxide (CO 2) as a C1 building block has attracted enormous attention. Carboxylation reactions, in particular, are of major interest for applications in isotope labeling. Due to the inexpensive nature of CO 2, information about its stoichiometric use is generally unavailable in the literature. Because of the rarity and limited availability of CO 2isotopomers, this parameter is of concern for applications in carbon-isotope labeling. We investigated the effects of the stoichiometry of labeled CO 2on carbon isotope exchange of phenyl? acetic acids. Both thermal and photocatalytic procedures were studied, providing insight into product outcome and isotope incorporation. Preliminary results on isotope-dilution effects of carbonate bases in photocatalytic carboxylation reactions have also been obtained.
ISOTOPICALLY ENRICHED PYRIMIDIN-5-YL ACETIC ACID DERIVATIVES AS CRTH2 ANTAGONISTS
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Page/Page column 21, (2011/08/03)
Provided herein are 2H- and 13C-enriched compounds of formula (I) or (II); wherein R is as defined herein, and wherein at least one hydrogen atom, in certain embodiments, three or more hydrogen atoms, are deuterium atoms or at least one carbon atom is a carbon-13 atom. Also provided are pharmaceutical compositions and methods using the 2H- and 13C-enriched compounds, useful for treating CRTH2-related diseases or disorders such as, for example, asthma, allergic rhinitis, atopic dermatitis, allergic conjuvatitis, Churg-Strauss syndrome, sinusitis, basophilic leukemia, chronic urticaria or basophilic leukocytosis.
Preparation of [carboxy-13C]4-nitrophenylacetic acid
Corrie, John E. T.,Ranjit,Munasinghe
, p. 231 - 233 (2007/10/03)
Reaction of sodium [13C]cyanide with excess benzyl chloride gave ～75% utilization of the isotope. Subsequent nitration, isomer separation and hydrolysis of the nitrile gave the required carboxy-labelled 4-nitrophenylacetic acid. Copyright
On rearrangements by cyclialkylations of arylpentanols to 2,3-dihydro-1H-indene derivatives. Part 4. The acid-catalyzed cyclialkylation of 2,4-dimethyl-2-phenyl[3-13C]pentan-3-ol
Fathi, Behrouz,Giovannini, Edgardo
, p. 2083 - 2088 (2007/10/03)
The cyclialkylation of 2,4-dimethyl-2-phenyl[3-13C]pentan-3-ol (4) gives only 2,3-dihydro-1,1,2,3- tetramethyl-1H-[3-13C]indene (6) (cf. Scheme 2) and not a trace of the isotopomeric 2,3-dihydro-1,1,2,3-tetramethyl-1H-[2-13C]indene (5). The mechanism proposed in [3] for the cyclialkylation of 4 (cf. Scheme 2, Path A) has, therefore, to be abandoned. The mechanism of Scheme 2, Path B, is proposed and may be considered as definitively established.
The synthesis of alkyl aryl nitriles from N-(1-arylalkylidene)-cyanomethylamines. Part 2. Mechanism
Perosa, Alvise,Selva, Maurizio,Tundo, Pietro
, p. 1033 - 1037 (2007/10/03)
The mechanism of the rearrangement of N-(1-arylalkylidene)cyanomethylamines ArC(=NCH2CN)R 1 to the corresponding nitriles ArCH(CN)R2 (in DMF, at 150°C, with K2CO3) is described. Reaction 1 → 2 was investigated for different types of imine 1, and it was found that with a leaving group other than CN- the reaction does not proceed to yield the nitrile, whereas imines such as PhC(=NCH2CN)H, prepared starting from aldehydes rather than ketones, yield the expected phenylacetonitrile even at temperatures as low as 120°C. Evidence for the mechanism comes from a study of the reactivity of the postulated intermediates: 2-cyano-3-phenylaziridine 4c, and 2,2-diphenyl-2H-azirine 5b. The route involving aziridine 4c is ruled out, since this compound does not react at all under the investigated conditions. The 2H-azirine 5b instead, yields the corresponding diphenylacetonitrile in DMF with K2CO3, at 150°C. The transformation seems to involve an initial deprotonation, followed by an intramolecular ring closure-CN elimination step, which yields the 2H-azirine. The azirine then isomerizes to the nitrile. Additional evidence for the intermediacy of the 2H-azirine, based on 1H NMR monitoring of the reaction 1 → 2, is described. Finally, the results of a simple isotope exchange experiment provide a rationale for the previously observed scrambling of labels, and further confirm the proposed mechanism.
Relative migratory aptitudes of hydrogen, benzoyl, 4-methoxyphenyl and 4-nitrophenyl groups in some unsaturated carbenes (vinylidenes)
Bertha, Ferenc,Fetter, József,Lempert, Károly,Kajtár-Peredy, Mária,Czira, Gábor,Koltai, Erno
, p. 8889 - 8895 (2007/10/03)
([5-13C] Tetrazol-5-yl)methyl ketones were prepared and subjected to oxidative fragmentation induced by lead tetraacetate. The resulting intermediate [1-13C]-3-oxoprop-1-en-1-ylidenes rearrange, depending on the relative migratory aptitudes of the benzoyl group and the ligands R, either to [3-13C]prop-2-yn-1-ones or to [2-13C]prop-2-yn-1-ones or to mixtures of the two isomers. The 1H and/or 13C NMR spectra of the products allow the three cases to be distinguished. The relative migratory aptitudes were found to be H>PhCO, 4-MeOC6H4>4-O2NC6H 4.
A plausible chemical analogy for biosynthesis of 2-arylbenzofuran of isoflavonoid origin and its application to synthesis of vignafuran
Kinoshita, Takeshi
, p. 259 - 262 (2007/10/03)
Treatment of 2-hydroxy-isoflav-3-ene with acid afforded 2-arylbenzofuran in good yield, and a mechanism for this chemical conversion involving loss of one carbon unit was described. This reaction scheme was suggested as a plausible chemical analogy for th
Synthesis and acidity constants of 13CO2H-labelled mono and dipyrrole carboxylic acids. pKa from 13C-NMR
Holmes, Darren L.,Lightner, David A.
, p. 1607 - 1622 (2007/10/02)
Six monocarboxylic acids were prepared highly enriched with 13C in their CO2H groups, and their pKa values were determined at low concentrations 10-4-10-5 M in H2O and in H2O-(CD3)2SO mixtures by analysis of pH-dependent 13CO2H NMR chemical shifts. Plots of the variation of CO2H(CO2-) 13C-NMR chemical shift vs pH gave a typical titration curve from which pKa's for [1-13C]-phenylpropionic (1) and [1-13C]-phenylacetic (2) acids were determined to be 4.60 and 4.16 respectively in H2O, and 4.67 and 4.31 respectively in H2O-27% vol (CD3)2SO. Bilirubin analogs, xanthobilirubic acid (5) and nor-xanthobilirubic acid (6) were determined to have pKa values of 4.76 and 4.64 respectively in H2O-27% vol (CD3)2SO, and extrapolated to pKa values and 4.62 and 4.51 in H2O.
Synthesis of Isotopically Labelled 3-Amino-2-phenylpropionic Acid and Its Role as a Precursor in the Biosynthesis of Tenellin and Tropic Acid
Cox, Russell J.,O'Hagan, David
, p. 2537 - 2540 (2007/10/02)
A synthesis of - and -3-amino-2-phenylpropionic acids 7a and 7b is described.The incorporation of this amino acid into tenellin 1 from Beauveria bassiana (Bals.) Vuill. and into tropic acid 10 moiety of the tropane alkaloids hyscoyamine 8 and scopolamine 9 from Datura innoxia was studied but proved unsuccessful in each case.
