Unravelling the Mechanism and Selectivity of the NHC‐catalyzed Three‐Membered Ring‐Opening/Fluorination of Epoxy Enals: A DFT Study

ChemCatChem ◽  
2019 ◽  
Vol 11 (12) ◽  
pp. 2919-2925 ◽  
Author(s):  
Yang Wang ◽  
Ling‐Bo Qu ◽  
Yu Lan ◽  
Donghui Wei
Keyword(s):  
Ring Opening ◽  
Membered Ring ◽  
Dft Study

Delineating the possibilities for intramolecular interception of the squarate ester cascade through the use of metalated enecarbamates

2000 ◽  
Vol 78 (6) ◽  
pp. 689-696 ◽  
Author(s):  
Jinsung Tae ◽  
Leo A Paquette
Keyword(s):  
Ring Opening ◽  
Membered Ring ◽  
Sequential Treatment ◽  
Nucleophilic Attack ◽  
Ring Strain ◽  
Multistep Process

Highly functionalized and annulated 2,4-cyclooctadienones are formed in a stereoselective manner by sequential treatment of squarate esters with a lithiated enecarbamate (six-membered ring or larger) and a cycloalkenyl- or 1-alkenyllithium reagent. The mechanistic details of this multistep process are presented. Particular attention is drawn to the step that involves intramolecular nucleophilic attack by a proximal oxido anion at the carbamate carbonyl and results in redirection of the cascade. This step is thwarted when five-membered cyclic enecarbamates are employed because of the excessive buildup of ring strain in the associated transition state.Key words: squarate esters, enecarbamates, conrotatory ring opening, intramolecular acylation, alkenyllithium reagents.

Effects of alkoxide alteration on the ring-opening polymerization of ε-caprolactone initiated by n-Bu3SnOR: a DFT study

2014 ◽  
Vol 26 (3) ◽  
pp. 695-703 ◽  
Author(s):  
Chanchai Sattayanon ◽  
Watit Sontising ◽  
Wanich Limwanich ◽  
Puttinan Meepowpan ◽  
Winita Punyodom ◽  
...  
Keyword(s):  
Ring Opening ◽  
Ring Opening Polymerization ◽  
Dft Study

sp3–sp2vs sp3–sp3C–C Site Selectivity in Rh-Catalyzed Ring Opening of Benzocyclobutenol: A DFT Study

2013 ◽  
Vol 136 (1) ◽  
pp. 169-178 ◽  
Author(s):  
Lina Ding ◽  
Naoki Ishida ◽  
Masahiro Murakami ◽  
Keiji Morokuma
Keyword(s):  
Ring Opening ◽  
Dft Study ◽  
Site Selectivity

ChemInform Abstract: Five- and Six-Membered Ring Opening of Pyroglutamic Diketopiperazine.

ChemInform ◽  
2010 ◽  
Vol 33 (34) ◽  
pp. no-no
Author(s):  
Dennis A. Parrish ◽  
Lon J. Mathias
Keyword(s):  
Ring Opening ◽  
Membered Ring

scholarly journals Divergent Reactivity of Indole-Tethered Ynones with Silver(I) and Gold(I) Catalysts: A Combined Synthetic and Computational Study

Synthesis ◽  
2018 ◽  
Vol 50 (24) ◽  
pp. 4829-4836 ◽  
Author(s):  
Jason Lynam ◽  
Richard Taylor ◽  
William Unsworth ◽  
John Liddon ◽  
James Rossi-Ashton ◽  
...  
Keyword(s):  
Ring Opening ◽  
Computational Study ◽  
Dft Study ◽  
Migration Mechanism ◽  
Catalyst Systems

A combined synthetic and computational (DFT) study has been performed to account for the divergent reactivity of indole-tethered ynones when treated with Ag(I) and Au(I) catalysts. The two catalyst systems deliver spirocyclic indolenines and carbazoles, respectively, from the same precursors, with the reaction outcomes believed to be a result of differences in the rates of a key protodemetalation step. A ring-opening/ring-closing isomerisation process is proposed to enable the interconversion of spirocyclic and C-2 annulated indole intermediates, in contrast to the 1,2-migration mechanism tentatively proposed in previous studies.

Thermal intramolecular reactions of Δ1-1,2,4-triazolines with extended exocyclic unsaturation

1988 ◽  
Vol 66 (3) ◽  
pp. 385-390 ◽  
Author(s):  
Adrian L. Schwan ◽  
John Warkentin
Keyword(s):  
Ring Opening ◽  
Hydrolysis Product ◽  
Sigmatropic Rearrangement ◽  
Membered Ring ◽  
Ring Closure ◽  
Experimental Results ◽  
First Order ◽  
Ring Opening Reaction ◽  
Intramolecular Reactions

Fumaratotriazoline (1) and amidotriazoline (3) undergo thermal first-order transformations in solution at 65 °C. The former affords the isomeric pyrrole 5 and its hydrolysis product 6. A mechanism involving opening of the initial five-membered ring to form 8, followed by closure to a new five-membered ring (9), is proposed. Amidotriazoline (3) loses N2 on heating to form 19. The experimental results are best accommodated in terms of a novel mechanism involving an electrocyclic ring closure, a [3 + 2] cycloreversion to form an ylide, a sigmatropic rearrangement of the ylide, and, finally, an electrocyclic ring-opening reaction.

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