𝔖 Bobbio Scriptorium
✦   LIBER   ✦

Bicyclic [b]-heteroannulated pyridazine derivatives. 4. Cyclization reactions of 4-aryltetrahydropyridazine-3,6-dione 3-hydrazones with some keto esters

✍ Scribed by Jerzy Lange; Elzbieta Pytlewska; Jan Plenkiewicz; Tomasz Kulinski; Janina Karolak-Wojciechowska; Slawomir Rump

Publisher
Journal of Heterocyclic Chemistry
Year
1997
Tongue
English
Weight
655 KB
Volume
34
Category
Article
ISSN
0022-152X

No coin nor oath required. For personal study only.

✦ Synopsis

Abstract

Ethoxycarbonylalkylidene derivatives 2 and 6 of the title hydrazones were obtained in the reaction with ethyl pyruvate or ethyl aroylformate and ethyl acetoacetate, respectively, in methanol. Both compounds were mixtures of geometric isomers with high predominance of one of them. Nmr spectroscopy revealed an unexpected magnetic non‐equivalence of the CH~2~ protons in the ester ethyl group of the major isomer of 6. On heating (˜200°) in an inert medium or on refluxing in ethanolic sodium ethoxide 2 cyclized to the corresponding pyridazino[6,1‐c]‐triazines 4, whereas 6 formed pyrazolylpyridazines 7. The structure of the latter was unambigously established by X‐ray analysis. Alkylation of 4a with benzyl bromide in the presence of tetrabutylammonium bromide occurred selectively on the pyridazine N atom.

📜 SIMILAR VOLUMES

Bicyclic [b]-heteroannulated pyridazine
Bicyclic [b]-heteroannulated pyridazine derivatives. 9. cyclization reactions of 4,4-dimethyl- and 4-phenyltetrahydropyridazine-3,6-dione 3-hydrazones with esters of keto dicarboxylic acids
✍ Krystyna Wejroch; Jerzy Lange; Anna Kielak; Janina Karolak-Wojciechowska; Jacek 📂 Article 📅 2001 🏛 Journal of Heterocyclic Chemistry 🌐 English ⚖ 132 KB

## Abstract Bis(ethoxycarbonyl)alkylidene derivatives **4** and **5** of the respective title hydrazones were obtained in the reactions with diethyl oxomalonate, diethyl oxosuccinate, diethyl 2‐oxoglutarate, and diethyl oxalo‐propionate as mixtures of geometric isomers with high predominance of one