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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
Author(s) -
Neidlein Richard,
Schröder Günter,
Krieger Claus,
Kikelj Danijel
Publication year - 1992
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/hlca.19920750407
Subject(s) - chemistry , ketene , acetal , reactivity (psychology) , betaine , bifunctional , nucleophile , derivative (finance) , medicinal chemistry , ethylene , stereochemistry , organic chemistry , medicine , alternative medicine , pathology , financial economics , economics , catalysis
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.