Intramolecular rearrangement in the 1,7-dioxa-8-azabicyclo[4,3,0]nonane series

1972 ◽  
Vol 21 (8) ◽  
pp. 1843-1843
Author(s):  
I. E. Chlenov ◽  
L. N. Kolymagina ◽  
V. A. Tartakovskii
Keyword(s):  
Intramolecular Rearrangement ◽  
Nonane Series

Thermo-Oxidative Decomposition of Lovage (Levisticum officinale) and Davana (Artemisia pallens) Essential Oils under Simulated Tobacco Heating Product Conditions

2020 ◽  
Vol 29 (1) ◽  
pp. 27-43
Author(s):  
Emma Jakab ◽  
Zoltán Sebestyén ◽  
Bence Babinszki ◽  
Eszter Barta-Rajnai ◽  
Zsuzsanna Czégény ◽  
...  
Keyword(s):  
Low Temperature ◽  
Essential Oils ◽  
Relative Yield ◽  
Gas Chromatography Mass Spectrometry ◽  
Intramolecular Rearrangement ◽  
Oxidation Reactions ◽  
Pyrolysis Gas ◽  
Oxidative Decomposition ◽  
Oxidative Pyrolysis ◽  
Artemisia Pallens

SummaryThe thermo-oxidative decomposition of lovage (Levisticum officinale) and davana (Artemisia pallens) essential oils has been studied by pyrolysis-gas chromatography/mass spectrometry in 9% oxygen and 91% nitrogen atmosphere at 300 °C to simulate low-temperature tobacco heating conditions. Both lovage and davana oils contain numerous chemical substances; the main components of both oils are various oxygen-containing compounds. Isobenzofuranones are the most important constituents of lovage oil, and their relative intensity changed significantly during oxidative pyrolysis. (Z)-ligustilide underwent two kinds of decomposition reactions: an aromatization reaction resulting in the formation of butylidenephthalide and the scission of the lactone ring with the elimination of carbon dioxide or carbon monoxide. Davanone is the main component of davana oil, which did not decompose considerably during low-temperature oxidative pyrolysis. However, the relative yield of the second most intensive component, bicyclogermacrene, reduced markedly due to bond rearrangement reactions. Davana ether underwent oxidation reactions leading to the formation of various furanic compounds. The changes in the composition of both essential oils could be interpreted in terms of bond splitting, intramolecular rearrangement mechanisms and oxidation reactions of several constituents during low-temperature oxidative pyrolysis. The applied thermo-oxidative method was found to be suitable to study the stability of the essential oils and monitor the decomposition products under simulated tobacco heating conditions. In spite of the complicated composition of the essential oils, no evidence for interaction between the oil components was found. [Beitr. Tabakforsch. Int. 29 (2020) 27–43]

scholarly journals Threonine 57 is required for the post-translational activation ofEscherichia coliaspartate α-decarboxylase

2014 ◽  
Vol 70 (4) ◽  
pp. 1166-1172 ◽  
Author(s):  
Michael E. Webb ◽  
Briony A. Yorke ◽  
Tom Kershaw ◽  
Sarah Lovelock ◽  
Carina M. C. Lobley ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Active Site ◽  
Site Directed Mutagenesis ◽  
Intramolecular Rearrangement ◽  
Directed Mutagenesis ◽  
Vitamin B ◽  
Biosynthesis Pathway ◽  
Serine Residue ◽  
Translational Activation

Aspartate α-decarboxylase is a pyruvoyl-dependent decarboxylase required for the production of β-alanine in the bacterial pantothenate (vitamin B5) biosynthesis pathway. The pyruvoyl group is formedviathe intramolecular rearrangement of a serine residue to generate a backbone ester intermediate which is cleaved to generate an N-terminal pyruvoyl group. Site-directed mutagenesis of residues adjacent to the active site, including Tyr22, Thr57 and Tyr58, reveals that only mutation of Thr57 leads to changes in the degree of post-translational activation. The crystal structure of the site-directed mutant T57V is consistent with a non-rearranged backbone, supporting the hypothesis that Thr57 is required for the formation of the ester intermediate in activation.

ChemInform Abstract: Photochemistry of the o-Nitrobenzyl System in Solution: Identification of the Biradical Intermediate in the Intramolecular Rearrangement

ChemInform ◽  
2010 ◽  
Vol 22 (42) ◽  
pp. no-no
Author(s):  
R. W. YIP ◽  
Y. X. WEN ◽  
D. GRAVEL ◽  
R. GIASSON ◽  
D. K. SHARMA
Keyword(s):  
Intramolecular Rearrangement

scholarly journals Electrosynthesis of 1,4-bis(diphenylphosphanyl) tetrasulfide via sulfur radical addition as cathode material for rechargeable lithium battery

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Dan-Yang Wang ◽  
Yubing Si ◽  
Wei Guo ◽  
Yongzhu Fu
Keyword(s):  
Density Functional ◽  
Chemical Space ◽  
Functional Materials ◽  
Radical Addition ◽  
Chemical Diversity ◽  
Energy Storage Materials ◽  
Intramolecular Rearrangement ◽  
Synthesis Methods ◽  
Dithiophosphinic Acid ◽  
Sulfur Radical

AbstractOrganic electrodes are promising as next generation energy storage materials originating from their enormous chemical diversity and electrochemical specificity. Although organic synthesis methods have been extended to a broad range, facile and selective methods are still needed to expose the corners of chemical space. Herein, we report the organopolysulfide, 1,4-bis(diphenylphosphanyl)tetrasulfide, which is synthesized by electrochemical oxidation of diphenyl dithiophosphinic acid featuring the cleavage of a P–S single bond and a sulfur radical addition reaction. Density functional theory proves that the external electric field triggers the intramolecular rearrangement of diphenyl dithiophosphinic acid through dehydrogenation and sulfur migration along the P–S bond axis. Impressively, the Li/bis(diphenylphosphanyl)tetrasulfide cell exhibits the high discharge voltage of 2.9 V and stable cycling performance of 500 cycles with the capacity retention of 74.8%. Detailed characterizations confirm the reversible lithiation/delithiation process. This work demonstrates that electrochemical synthesis offers the approach for the preparation of advanced functional materials.

Novel Peptide Dissociation:  Gas-Phase Intramolecular Rearrangement of Internal Amino Acid Residues

1997 ◽  
Vol 119 (24) ◽  
pp. 5481-5488 ◽  
Author(s):  
Richard W. Vachet ◽  
Barney M. Bishop ◽  
Bruce W. Erickson ◽  
Gary L. Glish
Keyword(s):  
Amino Acid ◽  
Gas Phase ◽  
Intramolecular Rearrangement ◽  
Amino Acid Residues ◽  
Peptide Dissociation
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