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Pseudo-Michael Reaction of 2-hydrazinoimidazolines: New Synthetic Approach to Imidazo[2,1-c][1,2,4]triazepine System
1  Department of Medicines Technology, Faculty of Pharmacy, Medical School, Staszica 6, PL.-20081 Lublin, Poland

Abstract: In a two-step reaction (pseudo-Michael/acylation) of 1-aryl-2-hydrazinoimidazolines with DEEM (diethyl ethoxymethylenemalonate) formation of 2,3-dihydroimidazo[2,1--c][1,2,4]triazepine system was observed. This type of reaction usually lead to formation of 5:6 or 6:6 membered fused hetero-cyclic systems whereas reaction of hydrazine derivatives (alkyl or aryl) or hydrazides and DEEM give pyrazoline carboxylates. In the literature formation of fused 1,2,4-tri-azepines in reaction of a-hydrazinoazoheterocycles is not mentioned. In first step of reaction of 1-aryl-2-hydrazinoimidazolines with Michael reagents chain enamine is formed.
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