The Diels-Alder Reaction from the EDA-NOCV Perspective: A Re-Examination of the Frontier Molecular Orbital Model

2018 ◽  
Vol 2019 (2-3) ◽  
pp. 478-485 ◽  
Author(s):  
Israel Fernández ◽  
Gernot Frenking
Keyword(s):  
Molecular Orbital ◽  
Alder Reaction ◽  
Diels Alder ◽  
Frontier Molecular Orbital ◽  
Diels Alder Reaction ◽  
Molecular Orbital Model

AM1 semiempirical study of benzopyrroles as dienes for Diels-Alder reaction

1996 ◽  
Vol 74 (1) ◽  
pp. 114-120 ◽  
Author(s):  
Branko S. Jursic
Keyword(s):  
Maleic Anhydride ◽  
Energy Gap ◽  
Alder Reaction ◽  
Qualitative Approach ◽  
Diels Alder ◽  
Frontier Molecular Orbital ◽  
Bond Orders ◽  
Diels Alder Reaction ◽  
Special Cases ◽  
Transition Structures

A qualitative approach for quick evaluation of the reactivity of dienes such as cyclopentadiene, furan, pyrrole, indole, and isoindole for Diels–Alder reactions was applied. As qualitative methods, the frontier molecular orbital (FMO) energy gap and the Hammond postulate through bond orders and energy of the reaction were evaluated for such dienophiles as ethylene, 1,3-dioxa-4-cyclopentene, and maleic anhydride. It was demonstrated that pyrrole and benzopyrroles are poor dienes in comparison with cyclopentadiene and furan. Because the reaction is controlled by the HOMO of the diene there are special cases when isoindole can react as a diene, while the loss of indole aromaticity in the course of the reaction precludes the cycloaddition. Geometries of transition structures and the accompanying activation energies were calculated for pyrrole, indole, and isoindole as dienes. The stereoselectivity of the reaction is discussed and compared with experimental results. Key words: benzopyrroles as dienes, Diels–Alder cycloaddition, Hammond postulate.

Thermodynamically controlled Diels–Alder reaction of 12-N-methylcytisine: A DFT study

2014 ◽  
Vol 13 (06) ◽  
pp. 1450048 ◽  
Author(s):  
Sophia S. Borisevich ◽  
Alena V. Kovalskaya ◽  
Inna P. Tsypysheva ◽  
Sergey L. Khursan
Keyword(s):  
Lewis Acids ◽  
Chemical Potential ◽  
Activation Parameters ◽  
Alder Reaction ◽  
Diels Alder ◽  
Dft Study ◽  
Frontier Molecular Orbital ◽  
Activation Barriers ◽  
Diels Alder Reaction ◽  
The Difference

A DFT study was performed for the Diels–Alder traction of 12-N-methylcytisine with a number of dienophiles (in boiling toluene under atmospheric pressure), namely, N-phenylmaleimide, maleic anhydride, 2,4-benzoquinone, tetracyanoethylene and methyl methacrylate. It was shown that 12-N-methylcytisine selectively reacts with these dienophiles, only the reaction with N-phenylmaleimide (NPM) resulting in the formation of thermodynamically stable adducts, which is consistent with experimental data. This selectivity of 12-N-methylcytisine is attributable to the difference between the properties of the listed dienophiles, which is confirmed by the relative reactivity indices calculated within the framework of the frontier molecular orbital (FMO) and hard and soft (Lewis) acids and bases (HSAB) theories, the thermodynamic and activation parameters of the forward and retro-Diels–Alder reactions. According to analysis of the theoretical results, NPM is characterized by high chemical potential, hardness close to that of 12-N-methylcytisine, and commensurable heights of the activation barriers for the forward and reverse Diels–Alder reactions and also forms stable [4+2] adducts.

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