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Neue thermische Reaktionen von 3 Amino- und 4-(Phenylthio)sydnonen mit Alkinen und Alkenen
Gotthardt, Hans,Reiter, Friedemann
, p. 2450 - 2464 (2007/10/02)
As cyclic azomethine imines, the 3-aminosydnones 1a - c, e - h react at 80 - 160 deg C with dimethyl acetylenedicarboxylate via non-isolable primary adducts 3 with evolution of carbon dioxide to produce the 1-aminopyrazoles 2a, c, d, e - h (yield 70 - 2percent) of table 1.Surprisingly, the analogous reactions of 1a, e proceed also with formation of the 1,2-oxazin-6-one derivative 4 as a result of an amino nitrene elimination from the primary adduct 3 which competes with the carbon dioxide elimination.In some cases, the 1-methylpyrazole 13, the pyridinetetracarboxylic ester18, as well as the benzothiophene derivative 19 are also isolable.Furthermore, the reactions of 1 with diphenylacetylene, styrene and dimethyl fumarate are described.
