scholarly journals Stereoselectivity through a network of non-classical CH weak interactions: a prospective study of a bicyclic organocatalytic scaffold

2014 ◽  
Vol 38 (12) ◽  
pp. 5975-5982 ◽  
Author(s):  
Jens H. Aasheim ◽  
Heike Fliegl ◽  
Einar Uggerud ◽  
Tore Bonge-Hansen ◽  
Odile Eisenstein

The preferred stereoisomeric product of this catalytic Diels–Alder reaction is in part determined by noncovalent CH⋯π interactions.

2019 ◽  
Vol 5 (11) ◽  
pp. eaax6707 ◽  
Author(s):  
Chi Zhang ◽  
Hongye Wang ◽  
Jie Zhong ◽  
Ye Lei ◽  
Renfeng Du ◽  
...  

By using click chemistry, a hexacationic cage was synthesized. The cage contains two triscationic π-electron–deficient trispyridiniumtriazine (TPZ3+) platforms that are bridged in a face-to-face manner by three ethylene-triazole-ethylene linkers. A diversity of π-electron–rich guests can be recognized within the pocket of the cage, driven by host-guest π-π interactions. The cage cavity acts as a protecting group, preventing an anthracene guest from undergoing Diels-Alder reaction. Under ultraviolet (UV) light, the pyridinium C─N bonds in TPZ3+ platforms are polarized and weakened, resulting in the occurrence of cage decomposition via β-elimination. Guest recognition could help to prevent this UV-stimulated cage decomposition by suppressing the excitation of the TPZ3+ units.


CrystEngComm ◽  
2015 ◽  
Vol 17 (46) ◽  
pp. 8933-8945 ◽  
Author(s):  
S. Khorasani ◽  
D. S. Botes ◽  
M. A. Fernandes ◽  
D. C. Levendis

During a SCSC solid-state Diels–Alder reaction, voids are created, followed by conformational change and crystal annealing that lead to the formation of new weak interactions.


Synlett ◽  
1989 ◽  
Vol 1989 (01) ◽  
pp. 30-32
Author(s):  
Thomas V. Lee ◽  
Alistair J. Leigh ◽  
Christopher B. Chapleo

2020 ◽  
Author(s):  
Radu Talmazan ◽  
Klaus R. Liedl ◽  
Bernhard Kräutler ◽  
Maren Podewitz

We analyze the mechanism of the topochemically controlled difunctionalization of C60 and anthracene, where an anthracene molecule is transferred from one C60 monoadduct to another one under exclusive formation of equal amounts of C60 and the difficult to make antipodal C60 bisadduct. Our herein disclosed dispersion corrected DFT studies show the anthracene transfer to take place in a synchronous retro Diels-Alder/Diels-Alder reaction: an anthracene molecule dissociates from one fullerene under formation of an intermediate, while already undergoing stabilizing interactions with both neighboring fullerenes, facilitating the reaction kinetically. In the intermediate, a planar anthracene molecule is sandwiched between two neighboring fullerenes and forms equally strong "double-decker" type pi-pi stacking interactions with both of these fullerenes. Analysis with the distorsion interaction model shows that the anthracene unit of the intermediate is almost planar with minimal distorsions. This analysis sheds light on the existence of noncovalent interactions engaging both faces of a planar polyunsaturated ring and two convex fullerene surfaces in an unprecedented 'inverted sandwich' structure. Hence, it sheds light on new strategies to design functional fullerene based materials.<br>


2016 ◽  
Vol 20 (22) ◽  
pp. 2421-2442 ◽  
Author(s):  
Kévin Cottet ◽  
Maria Kolympadi ◽  
Dean Markovic ◽  
Marie-Christine Lallemand

2014 ◽  
Vol 10 (6) ◽  
pp. 951-960
Author(s):  
Orazio Attanasi ◽  
Luca Bianchi ◽  
Maurizio D’Auria ◽  
Gianfranco Favi ◽  
Fabio Mantellini ◽  
...  

2018 ◽  
Vol 15 (2) ◽  
pp. 221-229 ◽  
Author(s):  
Shah Bakhtiar Nasir ◽  
Noorsaadah Abd Rahman ◽  
Chin Fei Chee

Background: The Diels-Alder reaction has been widely utilised in the syntheses of biologically important natural products over the years and continues to greatly impact modern synthetic methodology. Recent discovery of chiral organocatalysts, auxiliaries and ligands in organic synthesis has paved the way for their application in Diels-Alder chemistry with the goal to improve efficiency as well as stereochemistry. Objective: The review focuses on asymmetric syntheses of flavonoid Diels-Alder natural products that utilize chiral ligand-Lewis acid complexes through various illustrative examples. Conclusion: It is clear from the review that a significant amount of research has been done investigating various types of catalysts and chiral ligand-Lewis acid complexes for the enantioselective synthesis of flavonoid Diels-Alder natural products. The results have demonstrated improved yield and enantioselectivity. Much emphasis has been placed on the synthesis but important mechanistic work aimed at understanding the enantioselectivity has also been discussed.


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