Evidence of volume contraction in the transition state of the diels alder reaction
β Scribed by Kazuyoshi Seguchi; Akira Sera; Kazuhiro Maruyama
- Publisher
- Elsevier Science
- Year
- 1973
- Tongue
- French
- Weight
- 173 KB
- Volume
- 14
- Category
- Article
- ISSN
- 0040-4039
No coin nor oath required. For personal study only.
β¦ Synopsis
In the Diels Alder reactron the adduct with the endo conflguratlon ~3, m general,
- much preferred over the adduct having the exo conflguratlon. wooaward
π SIMILAR VOLUMES
We have recently determined kinetic parameters for the unimolecular Diels-Alder retrogressions of exe and w-dicyclopentadiene to monomer (1). The activation enthalpies and entropies are aH f (E) 37.4 2 0.3 kcal/mole, hSS (E) + 1.1 2 0.6 e.u., hH + (&) 33.0 2 0.5 kcal/mole, and hSS (endo) \_ -1.9 +
crease in the importance of these resonances structures in the transition state is more likely because of the greater double bond character between the inner carbon atoms which enhances other ionic resonance. Thus, no change or a slight decrease CH+ h -.\*1.46 -1.46
A transition structure with CS symmetry for the Diels-Alder reaction of butadiene with ethylene has been obtained with the STO-3G basis set. Stereochemical consequences are discussed. The Di&-Alder reaction of butadiene with ethylene has been studied by both ab initio',2 and a variety of -\_\_ semi-
The intramolecular hetero Diels-Alder reaction of heterodienes 13 is described. The heterodienes, which are obtained in situ by Knoevenagel condensation of aldehydes 129 -e with dimethylbarbituric acid (2), yield the cycloadducts 14a-e/15a-e and the ene adducts 169, c-e/17a, c-e. The ratio of 14/15