The Cyclopropylcarbinyl-Cyclobutyl-Homoallylic Rearrangement. Part III. Evidence for a symmetrical intermediate and for two discrete rearrangement processes
✍ Scribed by Manfred Geisel; Cyril A. Grob; René P. Traber; Werner Tschudi
- Publisher
- John Wiley and Sons
- Year
- 1976
- Tongue
- German
- Weight
- 879 KB
- Volume
- 59
- Category
- Article
- ISSN
- 0018-019X
No coin nor oath required. For personal study only.
✦ Synopsis
Abstract
In buffered 70% aqueous dioxane the cyclopropylcarbinyl (1‐X), endo‐cyclobutyl (2‐X) and homoallylic (3‐X) derivatives (X = nucleofuge) react to give the same mixture of alcohols 1‐OH and 3‐OH by way of a common intermediate, the symmetrical homoallylic ion 22. This follows from a study of optically active reactants 1‐X and 3‐X and from the deuterium scrambling pattern in the products from deuteriated 1‐X, endo‐2‐X and 3‐X. The high solvolysis rates of 3‐X indicated π‐bond participation in the transition state, while the high rates of 1‐X and endo‐2‐X reflect strong σ‐bond participation which is absent in exo‐2‐X.
Prolonged heating of 1‐X, endo‐2‐X and 3‐X in formic acid leads to a degenerate rearrangement of the initially formed 3‐formate. As evidenced by deuterium scrambling, carbon atoms 1, 3 and 7 eventually become positionally equivalent in the latter compound.