Organic transition states. V. The Diels-Alder reaction

1976 ◽  
Vol 98 (8) ◽  
pp. 2190-2198 ◽  
Author(s):  
R. E. Townshend ◽  
G. Ramunni ◽  
G. Segal ◽  
W. J. Hehre ◽  
L. Salem
Keyword(s):  
Transition States ◽  
Alder Reaction ◽  
Diels Alder ◽  
Diels Alder Reaction ◽  
Organic Transition

ChemInform Abstract: ORGANIC TRANSITION STATES. V. THE DIELS-ALDER REACTION

1976 ◽  
Vol 7 (27) ◽  
pp. no-no
Author(s):  
R. E. TOWNSHEND ◽  
G. RAMUNNI ◽  
G. SEGAL ◽  
W. J. HEHRE ◽  
L. SALEM
Keyword(s):  
Transition States ◽  
Alder Reaction ◽  
Diels Alder ◽  
Diels Alder Reaction ◽  
Organic Transition

QTAIM–DI–VISAB computational study on the Diels–Alder reaction of cyclopentadiene — On the nature of the so-called secondary orbital interactions

2008 ◽  
Vol 86 (7) ◽  
pp. 737-744 ◽  
Author(s):  
Nick Henry Werstiuk ◽  
Wojciech Sokol
Keyword(s):  
Computational Study ◽  
Transition States ◽  
Alder Reaction ◽  
Diels Alder ◽  
Physical Organic Chemistry ◽  
Hydrogen Atoms ◽  
Endo Isomer ◽  
Orbital Interactions ◽  
Physical Organic ◽  
Diels Alder Reaction

We have undertaken a QTAIM–DI–VISAB computational study of the dimerization of cyclopentadiene (1), the archetypal example of a Diels–Alder reaction that has been studied experimentally and computationally. Secondary orbital interactions (SOIs) that have gained acceptance in the interpretation of stereoselectivities seen in many cycloaddition reactions have been used to account for the fact that the endo isomer was the kinetic product of the reaction. To this point, “classical” MO analyses along with a variety of arbitrarily assigned solid and dashed lines (solid lines and bold dashes for “primary” interactions and dashed and dotted lines to differentiate between different SOI schemes) have been used in an attempt to describe the bonding of the transition states. Yet, the existence of SOIs has been challenged. Our interest in applying QTAIM to fundamental chemical problems in physical organic chemistry, with the goal of refining our knowledge of the bonding in transition-states and ground-state molecules while obviating the need to use a variety of confusing arbitrarily assigned dashed and dotted lines, led us to a QTAIM–DI–VISAB computational study of the endo and exo dimerizations of 1 at the DFT B3PW91 and MPW1PW91 levels. We have characterized the bonding interactions between cyclopentadiene rings in the various transition states and show that “normal” bonds are present where SOIs have been considered to exist. There is no need to use different types of dashed and dotted lines. An analysis of the changes in atom energies revealed that the significant destabilization of the carbon atoms in achieving the TSs (potentially leading to a very high barrier) is ameliorated by a stabilization of the hydrogen atoms leading to the relatively low barrier for the D–A reaction.Key words: cyclopentadiene dimerization, bispericyclic transition states, DFT calculations, QTAIM–DI–VISAB analysis, bonding, atom energy analysis.

scholarly journals Unusual Structure-Energy Correlations in Intramolecular Diels–Alder Reaction Transition States

Molecules ◽  
2014 ◽  
Vol 19 (10) ◽  
pp. 15535-15545 ◽  
Author(s):  
Justyna Żurek ◽  
Robert Rae ◽  
Martin Paterson ◽  
Magnus Bebbington
Keyword(s):  
Transition States ◽  
Alder Reaction ◽  
Diels Alder ◽  
Unusual Structure ◽  
Diels Alder Reaction

Organic reactions in liquid crystalline solvents. 2. An investigation into the use of liquid crystalline solvents to effect stereochemical control in the Diels–Alder reaction

1985 ◽  
Vol 63 (10) ◽  
pp. 2736-2741 ◽  
Author(s):  
William J. Leigh
Keyword(s):  
Liquid Crystalline ◽  
Transition States ◽  
Alder Reaction ◽  
Diels Alder ◽  
Shape Transition ◽  
Bimolecular Reactions ◽  
Solvent Phase ◽  
Stereochemical Control ◽  
Diels Alder Reaction ◽  
Liquid Crystalline Phases

The possibility of using liquid crystalline solvents to control the stereospecificity of bimolecular reactions as a result of differences in liquid crystalline solvation of the various possible transition states has been examined. The Diels–Alder reactions of 2,5-dimethyl-3,4-diphenylcyclopentadienone with four dienophiles of varying steric size (cyclopentene, cycloheptene, indene, and acenaphthylene) have been carried out in benzene, cholesteryl nonanoate (isotropic), cholesteryl propionate (cholesteric), and 4-ethyl-4′-(4-pentylcyclohexyl)biphenyl (smectic) at 105 °C. In spite of very large differences in steric solvation requirements for the endo- (globular in shape) and exo- (plate-like in shape) transition states in these reactions, no variation in product ratio with solvent phase is observed in any case.The inability of the ordered liquid crystalline phases to differentiate between endo- and exo-transition states in the Diels–Alder reactions investigated is rationalized as being the possible result of several factors. The most important of these are believed to be free volume effects, owing to both inefficient steric solvation of the bulky diene and volume contraction in the transition states for cycloaddition.

Diels–Alder reactions of 4,4-dimethyl-2-cyclohexenones. A direct route to the 4,4-dimethyl-1-decalones

1987 ◽  
Vol 65 (6) ◽  
pp. 1262-1278 ◽  
Author(s):  
Hsing-Jang Liu ◽  
Eric N. C. Browne
Keyword(s):  
Magnetic Resonance ◽  
Transition States ◽  
Alder Reaction ◽  
Diels Alder ◽  
Steric Effects ◽  
Reaction Products ◽  
Direct Route ◽  
Diels Alder Reaction ◽  
Chemical Techniques ◽  
Electronic And Steric Effects

Diels–Alder additions to enones 1 and 2, synthetic equivalents of the synthon 3, were studied using a variety of hydrocarbon dienes. The two enones have been shown to be effective and synthetically useful dienophiles. Spectroscopic (especially 1H and 13C magnetic resonance) and chemical techniques were used to define unambiguously the full structures of the adducts. The structures of the various reaction products were used to draw qualitative conclusions about the nature of the transition states involved and the various electronic and steric effects that play a role in the mechanistic course of the Diels–Alder reaction.

A theoretical study on the hetero-Diels–Alder reaction of phosphorous substituted diaza- and oxaza-alkenes with olefins derivatives

RSC Advances ◽  
2016 ◽  
Vol 6 (92) ◽  
pp. 89440-89449 ◽  
Author(s):  
M. Haghdadi ◽  
A. Abaszade ◽  
L. Abadian ◽  
N. Nab ◽  
H. Ghasemnejad Bosra
Keyword(s):  
Theoretical Study ◽  
Transition States ◽  
Alder Reaction ◽  
Diels Alder ◽  
Dft Studies ◽  
Concerted Mechanism ◽  
Diels Alder Reaction

DFT studies indicated that a hetero-Diels–Alder reaction of 4-phosphinyl and 4-phosphonyl-1,2-diaza- and 1,2-oxaza-1,3-butadienes with some olefins take place via an asynchronous concerted mechanism through endo or exo transition states.

Regiochemical aspects of Diels-Alder reactions of cyclopentadienone

1977 ◽  
Vol 30 (10) ◽  
pp. 2307 ◽  
Author(s):  
MN Paddon-Row ◽  
HK Patney ◽  
RN Warrener
Keyword(s):  
Kinetic Parameters ◽  
Transition States ◽  
Alder Reaction ◽  
Diels Alder ◽  
Cope Rearrangement ◽  
Diels Alder Reaction ◽  
Tentative Explanation

The regiochemistry of the Diels-Alder reaction between cyclopentadienone and 6,6-dimethylfulvene (isopropylidenecyclopentadiene) has been studied. Two adducts (in addition to cyclopentadienone dimer) were isolated and their structures were shown to be endo-10-isopropylidenetricyclo[5,2,1,02,6]-deca-4,8- dien-3-one (6a) and endo-3-isopropylidenetricyclo[5,2,1,02,6]deca-4,8- dien-10-one (7a). Kinetic parameters for the Cope rearrangement (6a) ↔ (7a) have been determined. The adducts (6a) and (7a) were formed in the ratio 45 : 55 respectively. Thus, in contrast to FMO predictions, and to its reaction with cyclopentadiene, cyclopentadienone tends to behave as a diene towards the fulvene. A tentative explanation of these results, based on angle strain in the transition states for the formation of Diels-Alder adducts, is proposed.

Studies on the transannular Diels–Alder reaction of 15-membered macrocyclic trienes containing a trans-trans diene. Part II: Evidence for unsymmetrical transition states in the formation of A.B.C.[6.6.7] tricyclic products

1995 ◽  
Vol 73 (10) ◽  
pp. 1695-1710 ◽  
Author(s):  
Dennis G. Hall ◽  
Renate Müller ◽  
Pierre Deslongchamps
Keyword(s):  
Lewis Acids ◽  
Transition States ◽  
Preceding Paper ◽  
Alder Reaction ◽  
Membered Ring ◽  
Diels Alder ◽  
Proximity Effects ◽  
Diels Alder Reaction ◽  
Stereocontrolled Synthesis ◽  
First Time

In the preceding paper (Part I) we described the preparation of 10 model TTT and TTC cyclopentadecatrienes. Their conversion to A.B.C.[6.6.7] tricyclic products via a transannular Diels–Alder (TADA) reaction and the analysis of the resulting diastereoselection along with proofs of structures are described in the present article (Part II). The required temperature of reaction was significantly higher (~100 °C) in comparison to that required for the 14-membered lower homologs, indicating that proximity effects are playing a key role in the TADA reaction. The presence of ester groups in the chain was found to favor either of the two possible transition states (endo or exo) on the basis of steric effects, thus controlling the TST/CSC ratio of tricycles from TTC macrocycles, and the TAC/CAT ratio from TTT macrocycles. A formyl substituent on the dienophile can further influence the diastereoselection through the hypothesis of unsymmetrical transition states and allowed, for the first time, the use of Lewis acids as catalysts in the TADA reaction. This investigation demonstrates a general methodology for the stereocontrolled synthesis of A.B.C.[6.6.7] tricycle structures related to several polycyclic natural products. Keywords: transannular, Diels–Alder, 15-membered ring, A.B.C.[6.6.7] tricycles, diterpene.

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