The Carbocation Rearrangement Mechanism, Clarified

2016 ◽  
Vol 81 (4) ◽  
pp. 1410-1415 ◽  
Author(s):  
Daniel J. S. Sandbeck ◽  
Daniel J. Markewich ◽  
Allan L. L. East
Keyword(s):  
Rearrangement Mechanism ◽  
Carbocation Rearrangement

What causes the nonclassical structure of 2-norbornyl ion?

2016 ◽  
Vol 94 (12) ◽  
pp. 1044-1048 ◽  
Author(s):  
Ruchit A. Patel ◽  
Allan L.L. East
Keyword(s):  
Computational Chemistry ◽  
Ring Strain ◽  
Rearrangement Mechanism ◽  
Carbocation Rearrangement ◽  
Additional Reason

A recent publication of a general carbocation rearrangement mechanism highlighted protonated cyclopropane (PCP+) intermediates, whose structures are meso between the nonclassical hypotheses of edge-PCP+ and corner-PCP+. Unlike the nonclassical structures, which possess 3-centre–2-electron bonds, the meso-PCP+ structures appear as closed classical structures. The 2-norbornyl ion, however, is known to have a nonclassical corner-PCP+ structure, and here we explore (using computational chemistry) the reasons why. The main reasons are due to the three 5-membered carbon rings, whose ring strain resist relaxation to a meso-PCP+ structure, but an additional reason is the trisubstitution on one side of the PCP+ face, which causes unfavourable C–C bond eclipsing.

scholarly journals Fusion genes in gynecologic tumors: the occurrence, molecular mechanism and prospect for therapy

2021 ◽  
Vol 12 (8) ◽  
Author(s):  
Bingfeng Lu ◽  
Ruqi Jiang ◽  
Bumin Xie ◽  
Wu Wu ◽  
Yang Zhao
Keyword(s):  
Tumor Progression ◽  
Massively Parallel Sequencing ◽  
Gynecologic Cancer ◽  
Endometrial Stromal Sarcoma ◽  
Driver Mutations ◽  
Fusion Genes ◽  
Stromal Sarcoma ◽  
Uterine Tumors ◽  
Rearrangement Mechanism ◽  
Gynecologic Tumors

AbstractGene fusions are thought to be driver mutations in multiple cancers and are an important factor for poor patient prognosis. Most of them appear in specific cancers, thus satisfactory strategies can be developed for the precise treatment of these types of cancer. Currently, there are few targeted drugs to treat gynecologic tumors, and patients with gynecologic cancer often have a poor prognosis because of tumor progression or recurrence. With the application of massively parallel sequencing, a large number of fusion genes have been discovered in gynecologic tumors, and some fusions have been confirmed to be involved in the biological process of tumor progression. To this end, the present article reviews the current research status of all confirmed fusion genes in gynecologic tumors, including their rearrangement mechanism and frequency in ovarian cancer, endometrial cancer, endometrial stromal sarcoma, and other types of uterine tumors. We also describe the mechanisms by which fusion genes are generated and their oncogenic mechanism. Finally, we discuss the prospect of fusion genes as therapeutic targets in gynecologic tumors.

scholarly journals Photoisomerization of 1-triphenylmethylcyclopentadiene. Di-π-methane rearrangement to 5,6,6-triphenylbicyclo[3.1.0]hex-2-ene

1977 ◽  
Vol 55 (1) ◽  
pp. 29-33 ◽  
Author(s):  
Stefan Weigl ◽  
John Warkentin
Keyword(s):  
Component Mixture ◽  
Two Component ◽  
Rearrangement Mechanism

Triphenylmethylcyclopentadiene exists as a mixture of isomers, the minor and major components of which are shown to be 1-triphenylmethylcyclopentadiene (1) and 2-triphenylmethyl-cyclopentadiene (2), respectively.Direct irradiation of a mixture of 1 and 2 led to formation of 5,6,6,-triphenylbicyclo[3.1.0]hex-2-ene (3) via rearrangement of 1. Acetophenone-sensitized irradiation of the same mixture gave 3 as well as a two component mixture of photodimers of 1 and/or 2. Results are interpreted in terms of the di-π-methane rearrangement mechanism.

The photochemistry of 5-cyano-2,3-benzobicyclo[4.2.0]octa-2,4,7-triene

1989 ◽  
Vol 67 (1) ◽  
pp. 82-87 ◽  
Author(s):  
Christopher Owen Bender ◽  
Douglas Dolman
Keyword(s):  
Excited State ◽  
Triplet Excited State ◽  
Deuterium Labelling ◽  
Direct Irradiation ◽  
Rearrangement Mechanism

The direct irradiation of 5-cyano-2,3-benzobicyclo[4.2.0]octa-2,4,7-triene (18) led to 6-cyanobenzocyclooctatetraene (17; Φ = 0.00075), 6-cyanobenzosemibullvalene (14; Φ = 0.0003), and 2-cyanonaphthalene (Φ = 0.00015). The triplet excited state of 18, generated by sensitization with a variety of ketone sensitizers (e.g., Michler's ketone and acetophenone), showed no unimolecular reactivity. Compound 18 does not participate in Zimmerman di-π-methane rearrangement; the potential product from such a transformation, 8-cyanobenzosemibullvalene (19), was, however, isolated from direct (Corex filter; Φ = 0,0010) irradiation of the semibullvalene 14. Deuterium labelling experiments suggest that 14 derives from a mechanism involving initial C4—C8 bonding of 18, and that cyclooctatetraene 17 is probably formed by simple electrocyclic opening of the cyclobutene ring of 18. Keywords: photochemistry, rearrangement mechanism, di-π-methane, semibullvalenes.

A Dynamic Rearrangement Mechanism of Web Page Layouts Using Web Agents

2009 ◽  
pp. 634-643 ◽  
Author(s):  
Masato Nakamura ◽  
Shohei Asami ◽  
Tadachika Ozono ◽  
Toramatsu Shintani
Keyword(s):  
Web Page ◽  
Rearrangement Mechanism
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