Concerted vs Stepwise Mechanism in 1,3-Dipolar Cycloaddition of Nitrone to Ethene, Cyclobutadiene, and Benzocyclobutadiene. A Computational Study

2000 ◽  
Vol 65 (19) ◽  
pp. 6112-6120 ◽  
Author(s):  
Cristiana Di Valentin ◽  
Mauro Freccero ◽  
Remo Gandolfi ◽  
Augusto Rastelli
Keyword(s):  
Computational Study ◽  
Dipolar Cycloaddition ◽  
Stepwise Mechanism

Beyond the Alternatives that Switch the Mechanism of the 1,3-Dipolar CyCloadditions from Concerted to Stepwise or Vice Versa: A Literature Review

2016 ◽  
Vol 41 (4) ◽  
pp. 331-344 ◽  
Author(s):  
Seyyed Amir Siadati
Keyword(s):  
Organic Chemistry ◽  
Literature Review ◽  
Cycloaddition Reaction ◽  
Dipolar Cycloaddition ◽  
Stepwise Mechanism ◽  
Dipolar Cycloadditions ◽  
Catalyst Free ◽  
Number Of Factors ◽  
Reaction Channels ◽  
The 1960S

For several decades, the concerted or stepwise character of the mechanism of the 1,3-dipolar cycloaddition reaction has been one of the most debated issues in the field of organic chemistry. The significance of this problem is due to the fact that in a catalyst-free 1,3-dipolar cycloaddition, when the mechanism switches from concerted to stepwise, the stereospecificity is lost and thus unwanted stereoisomers may emerge. The first proposals about the mechanism of the 1,3-dipolar reaction were due to Huisgen (concerted model) and subsequently by Firestone (two-step diradical channel) in the 1960s. After a decade of debate, most researchers accepted the concerted model for the reaction, but during these years, researchers reported some examples of the stepwise mechanism for catalyst-free 1,3-dipolar cycloadditions. This review attempts to find a number of factors that could influence the reaction channels and switch the mechanism from concerted to stepwise, or vice versa.

Investigating the reaction pathways of chemical functionalization of C20 fullerene by nitrile oxide and azide; A computational study

2018 ◽  
Vol 17 (01) ◽  
pp. 1850003
Author(s):  
Sakineh Asghari ◽  
Ali Asghar Gouran ◽  
Davood Farmanzadeh ◽  
Tahereh Abdollahi
Keyword(s):  
Functional Group ◽  
Computational Study ◽  
Cycloaddition Reaction ◽  
Nitrile Oxide ◽  
Dipolar Cycloaddition ◽  
Hydrazoic Acid ◽  
Density Of State ◽  
Electronic Density ◽  
C20 Fullerene ◽  
Oxide Group

In this study, the interactions between nitrile oxide (fulminic acid) and azide (hydrazoic acid) with the C[Formula: see text] fullerene were investigated and their priority in reacting and functionalizing surface of this fullerene were compared with each other. The results show that the 1,3-dipolar cycloaddition reaction between fulminic acid and C[Formula: see text] fullerene could occur faster than this reaction by hydrazoic acid. Therefore, nitrile oxide group as a dipole is much preferred compared to the azide functional group in reacting with the surface of C[Formula: see text] fullerene. In addition, the calculated adsorption energy and electronic density of state, DOS plots for the related species confirmed that the C[Formula: see text] fullerene can be used as sensors for sensing the hydrazoic acid and fulminic acid molecules.

scholarly journals A DFT Study on the Molecular Mechanism of Additions of Electrophilic and Nucleophilic Carbenes to Non-Enolizable Cycloaliphatic Thioketones

Molecules ◽  
2021 ◽  
Vol 26 (18) ◽  
pp. 5562
Author(s):  
Grzegorz Mlostoń ◽  
Karolina Kula ◽  
Radomir Jasiński
Keyword(s):  
Molecular Mechanism ◽  
Sulfur Atom ◽  
Molecular Mechanisms ◽  
Computational Study ◽  
Cycloaddition Reaction ◽  
Single Step ◽  
Stepwise Mechanism ◽  
Nucleophilic Carbenes ◽  
Transient Intermediate ◽  
Single Step Reaction

The molecular mechanisms of addition of dihalocarbenes and dimethoxycarbene to thioketones derived from 2,2,4,4-tetrmethylcyclobutane-1,3-dione were examined on the basis of the DFT wb97xd/6-311g(d,p)(PCM) calculations. Obtained results demonstrated that the examined processes exhibit polar nature and in the case of electrophilic dichloro-, and dibromocarbenes are initiated by the attack of carbene species onto the sulfur atom of the C=S group. Remarkably, reactions involving more electrophilic carbenes (dichloro-, and dibromocarbene) proceeds via stepwise mechanism involving thiocarbonyl ylide as a transient intermediate. In contrast, analogous reactions with nucleophilic dimethoxycarbene occur via a single step reaction, which can be considered as the [2 + 1] cycloaddition reaction initiated by the attack onto the C=S bond. A computational study showed that difluorocarbene tends to react as a nucleophilic species and resembles rather dimethoxycarbene and not typical dihalocarbene species. Significantly higher reactivity of the thioketone unit in comparison to the ketone group, both present in 3-thioxo-2,2,4,4-tetramthylcyclobutanone molecule, was rationalized in the light of DFT computational study.

1,3-Dipolar cycloaddition of azomethine ylide with ethene and 2-butene: a computational study

2005 ◽  
Vol 46 (12) ◽  
pp. 1993-1995 ◽  
Author(s):  
Fillmore Freeman ◽  
Phuong Dang ◽  
Angela C. Huang ◽  
Aline Mack ◽  
Kara Wald
Keyword(s):  
Computational Study ◽  
Azomethine Ylide ◽  
Dipolar Cycloaddition
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