Characteristics of the Two Frontier Orbital Interactions in the Diels−Alder Cycloaddition

2004 ◽  
Vol 69 (3) ◽  
pp. 757-764 ◽  
Author(s):  
Claude Spino ◽  
Hadi Rezaei ◽  
Yves L. Dory
Keyword(s):  
Diels Alder ◽  
Frontier Orbital ◽  
Orbital Interactions

Frontier orbital interactions in the hetero Diels–Alder cycloaddition of diazadienes

2008 ◽  
Vol 86 (5) ◽  
pp. 384-394 ◽  
Author(s):  
Pratibha Sharma ◽  
Ashok Kumar ◽  
Vinita Sahu ◽  
Jitendra Singh
Keyword(s):  
Chemical Potential ◽  
Molecular Orbital Calculation ◽  
Diels Alder ◽  
Reaction Pathways ◽  
Electronic Charge ◽  
Chemical Hardness ◽  
Frontier Orbital ◽  
Electrophilicity Index ◽  
Reactivity Pattern ◽  
Orbital Interactions

This work deals with the molecular orbital calculation studies performed on different diazadienes to assess their reactivity pattern. The interaction of these diazadienes with various electron-poor and electron-rich dienophiles leads to the formation of diazines and tetrazines as the cycloadducts. The results from frontier orbital interactions were used to rationalize the reactivity and predictability of NDAC and IEDDAC reaction pathways. Correlation studies were also performed to predict reactivity sequence using a number of electronic descriptors, such as electrophilicity index (ω), chemical potential (µ), electronic charge ΔNmax, and chemical hardness η. Moreover, these studies exhibit good compatibility with experimental observations.Key words: AM1, MNDO, PM3, diazadienes, tetrazines, electrophilicity index, chemical potential.

The Syntheses and Crystal-Structures of Decahydro-5,14:6,13:7,12-Trimethanopentacene and Decahydro-5,14-7,12-Dimethanopentacene: Two Useful Molecules for Investigating Laticyclic Hyperconjugation

1986 ◽  
Vol 39 (10) ◽  
pp. 1587 ◽  
Author(s):  
DC Craig ◽  
MN Paddonrow ◽  
HK Patney
Keyword(s):  
Crystal Structure ◽  
Ab Initio Calculations ◽  
Crystal Structures ◽  
Reductive Dechlorination ◽  
Photoelectron Spectrum ◽  
Alder Reaction ◽  
Diels Alder ◽  
Basis Set ◽  
Orbital Interactions ◽  
Diels Alder Reaction

The syntheses of decahydro-5,14:6,13:7,12-trimethanopentacene and decahydro-5,14:7,12-dimethanopentacene are described (see Schemes 1 and 2 respectively). Diels -Alder reaction of diene (10) with two equivalents of tetrachlorothiophen 1,1-dioxide (11) gave the adduct (12), which was aromatized to (13) through treatment with base. Reductive dechlorination (Na/ PriOH ) of (13) gave (6). A similar set of reactions performed on (17), itself prepared from cyclohexa-1,4-diene and two equivalents of hexachlorocyclopentadiene (15), gave (7). The crystal structures of (6) and (7) were determined. An interesting feature of the structure of (7) is the slight endo pyramidalization (by c. 3°) of the trigonal carbon atoms C 4a, C 7a, C 11a and C 14a. Model ab initio calculations (STO-3G basis set) on complexes (27) and (28), whose geometries were culled from the crystal structure of (6), indicate that significant laticyclic hyperconjugative interactions (c. 0.3 eV ) are mainly responsible for causing the observed splitting between the πs+πs and πs-πs levels in the photoelectron spectrum of (6). Orbital interactions through the pair of six connecting sigma bonds (OIT-6-B) in (6) have a negligible effect (c. 0.08 eV ) on these levels. In agreement with prediction, laticyclic hyperconjugation does not affect the πa+πa and πa-πa levels.

Secondary orbital interactions determining regioselectivity in the Diels-Alder reaction. 5. Thio-substituted 1,3-butadienes

1983 ◽  
Vol 48 (25) ◽  
pp. 5051-5054 ◽  
Author(s):  
Peter V. Alston ◽  
Michael D. Gordon ◽  
Raphael M. Ottenbrite ◽  
Theodore Cohen
Keyword(s):  
Alder Reaction ◽  
Diels Alder ◽  
Orbital Interactions ◽  
Diels Alder Reaction
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