Heterocyclen aus Bis(alkoxycarbonyl)keten-ethylen-acetalen ( = Dialkyl-2-(1,3-dioxolan-2-yliden)propan-1,3-dioate). Synthese und Eigenschaften einer neuen Klasse von Pyrazolium-Betainen
✍ Scribed by Richard Neidlein; Günter Schröder; Claus Krieger; Danijel Kikelj
- Publisher
- John Wiley and Sons
- Year
- 1992
- Tongue
- German
- Weight
- 796 KB
- Volume
- 75
- Category
- Article
- ISSN
- 0018-019X
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✦ Synopsis
Heterocycles Starting from Bis(alkoxycarbonyl)ketene Ethylene Acetals ( = Dialkyl 2‐(1,3‐Dioxolan‐2‐ylidene)propane‐1,3‐dioate). Synthesis and Properties of a New Class of Pyrazolium Betaines
The readily available bis(alkoxycarbonyl)ketene ethylene acetals 1 react with bifunctional nucleophiles to give heterocycles 2–5 (Scheme 1). Their reactions with N,N‐dialkylhydrazines lead to the pyrazolium betaines 7a–f (Scheme 4). Cyclic N,N‐dialkylhydrazines give spiro compounds 7d–f. The reaction of thioketene acetal 12 and of the derivative 15 of methanetricarboxylic acid with N,N‐dimethylhydrazine results in the formation of 3‐(methylthio)‐ and 3‐methoxypyrazolium betaine 7g and 7h, respectively (Scheme 4). The chemical reactivity of the synthesized pyrazolium betaines 7 was tested. The structure of the 3‐(methylthio) derivative 7g was determined by X‐ray analysis.