Additionsreaktionen von 2-Amino-1-azetinen mit Cyclopropenonen; Bildung von Azepinderivaten durch Ringerweiterung. Vorläufige Mitteilung
✍ Scribed by Friedrich Stierli; Roland Prewo; Jost H. Bieri; Heinz Heimgartner
- Publisher
- John Wiley and Sons
- Year
- 1983
- Tongue
- German
- Weight
- 500 KB
- Volume
- 66
- Category
- Article
- ISSN
- 0018-019X
No coin nor oath required. For personal study only.
✦ Synopsis
Addition Reactions of 2‐Amino‐1‐azetines with Cyclopropenones; Formation of Azepine Derivatives by Ring Expansion Reactions
The reaction of 2‐amino‐1‐azetines of type 6 with 2,3‐diphenylcyclopropenone (1a) in acetonitrile leads to azetol[1,2‐α]pyrroles (cf. 7 and 9, Schemes 3 and 4) in good yield. It is remarkable that in the reaction of 6a with 1a only endo‐7 is formed. With silicagel in ether endo‐7 isomerizes to the thermodynamically more stable exo‐7 (Schemes 3 and 6). The crystal structure of the latter compound has been established by X‐ray crystallography. The reaction of 6a and 2‐isopropyl‐3‐phenyl‐cyclopropenone (1b) yields only one product, which isomerizes with silicagel in ether to exo‐10 (Scheme 4). The structure of exo‐10 has been determined by NMR‐spectroscopy. It seems reasonable that this structure results from a nucleophilic attack of the four‐membered amidine to the phenyl‐substituted C‐atom of 1b.