An interesting ring cleavage of a 1,2,4-oxadiazole ring

2017 ◽  
Vol 41 (12) ◽  
pp. 4797-4801 ◽  
Author(s):  
Qiong Yu ◽  
Guangbin Cheng ◽  
Xuehai Ju ◽  
Chunxu Lu ◽  
Hongwei Yang
Keyword(s):  
Detonation Velocity ◽  
Ring Opening ◽  
Impact Sensitivity ◽  
Ring Cleavage ◽  
Oxygen Balance ◽  
Zero Density ◽  
Ring Opening Reaction ◽  
Acidic Conditions

Ring-opening reaction: owing to the instability of the 1,2,4-oxadiazole ring under acidic conditions, unexpected compounds 2 and 3 were obtained. Compound 2 exhibits an oxygen balance of zero, density of 1.89 g cm−1 and detonation velocity of 9307 m s−1 as well as impact sensitivity of 20 J.

ChemInform Abstract: Ring-Opening Reaction in Acidic Conditions of Tetraazapentalene Derivatives Containing a Hypervalent Sulfur.

ChemInform ◽  
2010 ◽  
Vol 22 (20) ◽  
pp. no-no
Author(s):  
M. TOMURA ◽  
N. MATSUMURA ◽  
O. MORI ◽  
H. CHIKUSA ◽  
S. KAMITANI ◽  
...  
Keyword(s):  
Ring Opening ◽  
Ring Opening Reaction ◽  
Acidic Conditions

Cycloadditionen von Ketenen mit Fulvenen/Cycloadditions of Ketenes with Fulvenes

1983 ◽  
Vol 38 (4) ◽  
pp. 504-515 ◽  
Author(s):  
Willy Friedrichsena ◽  
Tony Debaerdemaeker ◽  
Andreas Böttcher ◽  
Sabine Hahnemann ◽  
Regine Schmidt
Keyword(s):  
Ring Opening ◽  
Sodium Methoxide ◽  
Ring Cleavage ◽  
X Ray ◽  
X Ray Crystallography ◽  
Ring Opening Reaction ◽  
Acid Catalyzed

Fulvenes (1) add ketenes (2) in a [ π 2 + π 2] manner to give bicyclo[3.2.0]heptenes (3). Ring cleavage with sodium methoxide yields dihydrofulvenes (4) which can be deliydrogenated to give fulvenes (5), whereas the acid catalyzed ring opening reaction of 3 leads to fulvenes (6). The structure of 3h has been clarified by X-ray crystallography.

Ring-opening reaction in acidic conditions of tetraazapentalene derivatives containing a hypervalent sulfur

1990 ◽  
Vol 27 (7) ◽  
pp. 2215-2217 ◽  
Author(s):  
Masaaki Tomura ◽  
Noboru Matsumura ◽  
Osamu Mori ◽  
Hisashi Chikusa ◽  
Shigeki Kamitani ◽  
...  
Keyword(s):  
Ring Opening ◽  
Ring Opening Reaction ◽  
Acidic Conditions

On the Conrotatory Ring Opening of 3-Carbomethoxycyclobutene Vis-À-Vis 3-Carbomethoxy-1,2-Benzocyclobutene and the Predominant Inward Opening of 3-Dimethylaminocarbonyl-1,2-Benzocyclobutene

2018 ◽  
Author(s):  
Veejendra Yadav ◽  
Dasari L V K Prasad ◽  
Arpita Yadav ◽  
Maddali L N Rao
Keyword(s):  
Transition State ◽  
Ring Opening ◽  
Electron Process ◽  
Ring Opening Reaction ◽  
Stable Species ◽  
Electron Event

<p>The torquoselectivity of conrotatory ring opening of 3-carbomethoxycyclobutene is controlled by p<sub>C1C2</sub>→s*<sub>C3C4</sub> and s<sub>C3C4</sub>→p*<sub>CO</sub> interactions in the transition state in a 4-electron process as opposed to only s<sub>C3C4</sub>→p*<sub>CO</sub> interaction in an apparently 8-electron event in 3-carbomethoxy-1,2-benzocyclobutene. The ring opening of 3-carbomethoxy-1,2-benzocyclobutene is sufficiently endothermic. We therefore argue that the reverse ring closing reaction is faster than the forward ring opening reaction and, thus, it establishes an equilibrium between the two and subsequently allows formation of the more stable species <i>via</i> outward ring opening reaction. Application of this argument to 3-dimethylaminocarbonyl-1,2-benzocyclobutene explains the predominantly observed inward opening.</p>

scholarly journals Expanding Monomers as Anti-Shrinkage Additives

Polymers ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 806
Author(s):  
Philipp Marx ◽  
Frank Wiesbrock
Keyword(s):  
Ring Opening ◽  
Covalent Bond ◽  
Volumetric Shrinkage ◽  
Structure Property ◽  
Atomic Packing ◽  
Materials Properties ◽  
Volumetric Expansion ◽  
Structure Property Relationships ◽  
Ring Opening Reaction ◽  
Measuring Techniques

Commonly, volumetric shrinkage occurs during polymerizations due to the shortening of the equilibrium Van der Waals distance of two molecules to the length of a (significantly shorter) covalent bond. This volumetric shrinkage can have severe influence on the materials’ properties. One strategy to overcome this volumetric shrinkage is the use of expanding monomers that show volumetric expansion during polymerization reactions. Such monomers exhibit cyclic or even oligocyclic structural motifs with a correspondingly dense atomic packing. During the ring-opening reaction of such monomers, linear structures with atomic packing of lower density are formed, which results in volumetric expansion or at least reduced volumetric shrinkage. This review provides a concise overview of expanding monomers with a focus on the elucidation of structure-property relationships. Preceded by a brief introduction of measuring techniques for the quantification of volumetric changes, the most prominent classes of expanding monomers will be presented and discussed, namely cycloalkanes and cycloalkenes, oxacycles, benzoxazines, as well as thiocyclic compounds. Spiroorthoesters, spiroorthocarbonates, cyclic carbonates, and benzoxazines are particularly highlighted.

scholarly journals Synthesis and Antiproliferative Activity of Phosphorus Substituted 4-Cyanooxazolines, 2-Aminocyanooxazolines, 2-Iminocyanooxazolidines and 2-Aminocyanothiazolines by Rearrangement of Cyanoaziridines

Molecules ◽  
2021 ◽  
Vol 26 (14) ◽  
pp. 4265
Author(s):  
Victor Carramiñana ◽  
Ana M. Ochoa de Ochoa de Retana ◽  
Francisco Palacios ◽  
Jesús M. de los de los Santos
Keyword(s):  
Ring Opening ◽  
Human Lung ◽  
Ring Expansion ◽  
Moderate Activity ◽  
A549 Cell Line ◽  
One Pot ◽  
Acidic Conditions ◽  
Lung Adenocarcinoma A549 ◽  
High Yields

Several phosphorus-substituted N-acylated cyanoaziridines 2 and N-carbamoylated cyanoziridines 5 were prepared in good to high yields. N-Acylated cyanoaziridines 2 were used, after ring expansion, in an efficient synthesis of oxazoline derivative 3a and in a completely regio-controlled reaction in the presence of NaI. Conversely, N-carbamoyl cyanoaziridines 5 reacted with NaI to obtain a regioisomeric mixture of 2-aminocyanooxazolines 7. Mild acidic conditions can be used for the isomerization of N-thiocarbamoyl cyanoaziridine 6a into a 2-aminocyanothiazoline derivative 8a by using BF3·OEt2 as a Lewis acid. Likewise, a one pot reaction of NH-cyanoaziridines 1 with isocyanates obtained 2-iminocyanooxazolidines 9 regioselectively. This synthetic methodology involves the addition of isocyanates to starting cyanoaziridines to obtain N-carbamoyl cyanoaziridines 5, which after the ring opening, reacts with a second equivalent of isocyanate to give the final 2-imino cyanooxazolidines 9. In addition, the cytotoxic effect on the cell lines derived from human lung adenocarcinoma (A549) was also screened. 2-Iminooxazolidines 9 exhibited moderate activity against the A549 cell line in vitro. Furthermore, a selectivity towards cancer cells (A549) over non-malignant cells (MCR-5) was detected.

Design and synthesis of 1,8-Naphthalimide Functionalized Benzothiadiazoles

2021 ◽  
Author(s):  
Rajneesh Misra ◽  
Yogjivan Rout
Keyword(s):  
Ring Opening ◽  
Coupling Reaction ◽  
Cross Coupling ◽  
Design And Synthesis ◽  
Cross Coupling Reaction ◽  
Ring Opening Reaction

A series of multi acceptor based push-pull derivatives BTD2–BTD5 were designed and synthesized via Pd-catalyzed Sonogashira cross-coupling reaction followed by [2+2] cycloaddition–electrocyclic ring-opening reaction in which benzothiadiazole (BTD, A1), naphthalimide...

scholarly journals (1R,4S,5S)-5-((3-Hydroxypropyl)amino)-4-((1-Methyl-1H-tetrazol-5-yl)thio)Cyclopent-2-en-1-ol

Molbank ◽  
10.3390/m1199 ◽  
2021 ◽  
Vol 2021 (2) ◽  
pp. M1199
Author(s):  
Milene A. G. Fortunato ◽  
Filipa Siopa ◽  
Carlos A. M. Afonso
Keyword(s):  
Spectral Data ◽  
13C Nmr ◽  
Ring Opening ◽  
Environmentally Friendly ◽  
Mass Spectral Data ◽  
Mass Spectral ◽  
Excellent Yield ◽  
Ring Opening Reaction ◽  
Nucleophilic Ring Opening

Using environmentally friendly conditions, the nucleophilic ring-opening reaction of 6-azabicyclo[3.1.0]hex-3-en-2-ol with 1-methyl-1H-tetrazole-5-thiol provided a novel thiol-incorporated aminocyclopentitol, (1R,4S,5S)-5-((3-hydroxypropyl)amino)-4-((1-methyl-1H-tetrazol-5-yl)thio)cyclopent-2-en-1-ol, in excellent yield (95%). The newly synthesized compound was analyzed and characterized via 1H, 13C-NMR, HSQC, and mass spectral data.

ChemInform Abstract: Asymmetric Alkynylative Ring Opening Reaction of Oxabenzonorbornadienes Promoted by Palladium/Silver Cocatalytic System.

ChemInform ◽  
2015 ◽  
Vol 46 (12) ◽  
pp. no-no
Author(s):  
Shanshan Liu ◽  
Sifeng Li ◽  
Hualei Chen ◽  
Qingjing Yang ◽  
Jianbin Xu ◽  
...  
Keyword(s):  
Ring Opening ◽  
Ring Opening Reaction ◽  
Palladium Silver
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