Reaktion von 2‐Thiophenaminen mit Hydrazin

Reaction of 2‐Thiophenamines with Hydrazine Depending on their substituents 2‐thiophenamines react with hydrazine hydrate on different ways: Hydrazinolysis of the ester 1 yields the 2‐amino‐3‐thiophenecarbohydrazide 2 . 4‐Phenyl‐2‐thiophenamine ( 4 ) is converted into the 2(5 H )‐thiophenone hydrazone 5 by exchange of the amino group. The thiophenamines 7, 9, 12 undergo ring transformation to yield pyridazine derivatives, the N,N′ ‐bis(dihydro‐3‐pyridazinyl)hydrazine 8 , the 3‐pyridazinylhydrazine 10 , and the pyrazolo[3,4‐ c ]pyridazine 13 . From 10 the 1,2,4‐triazolo[4,3‐ b ]pyridazine 11 is obtained.