ChemInform Abstract: PYRIDAZINES. LXXVIII. USE OF N,N‐DIMETHYLAMINOMETHYLENE DERIVATIVES OF SOME AMINO AND HYDRAZINO HETEROCYCLES IN ORGANIC SYNTHESIS

Abstract

Die Bildung der N,N‐ Dimethylaminomethylenhydrazino‐Derivate (II) von Pyridazin bzw. (IV) von Azolopyridazinen erfolgt durch Umsetzung ihrer Hydrazino‐Derivate mit N,N‐Dimethyl‐ ′7/1 formamidacetalen.

Heterocycles. 167. Telesubstitution and other transformations of imidazo[1,2-a]- and s-triazolo[4,3-a]pyrazines

“…Some water was added and the residue was filtered (65 mg). Both products were found to be identical, and they were combined and crystallized from water: mp 95-96 °C (yield 26 3-Phenyl-5-phenylthio-s-triazolo[4,3-a]pyrazine (20, R = Ph, Ri = SPh) was prepared in a similar manner in 52% yield: mp [194][195][196][197][198] °C; MS m/e 304 (M); NMR (Me2SO-d6) 7.9 (s, H6), 9.25 (s, Hg), 7,43 (m, Ph), 6.8, 7.23 (m, 3-Ph).…”

“…We have attempted also another approach for the synthesis of s-triazolo[4,3-ajpyrazines, which proved to be successful in the pyridazine series. 26 From hydrazinopyrazines and N,Ndimethylformamide dimethyl acetal the corresponding N,Ndimethylaminomethylenehydrazine derivatives were prepared, but attempts to cyclize these were unsuccessful.…”

Oximes of five-membered heterocyclic compounds with three and four heteroatoms 1. Synthesis and structure (review)

“…Triazole amidoximes are usually obtained from the corresponding nitriles and hydroxylamine in ethanol [17], but imines can also be used for this purpose. Thus, 6-hydroxyiminomethyleneiminotriazolo- [4,3-b]pyridazine (18) was obtained from the imine 17 in the NH 2 OH·HCl/NaOMe system [18]. A good leaving group in this reaction is benzotriazole.…”

Oximes of six-membered heterocyclic compounds with two and three heteroatoms. II.* Reactions and biological activity (review)

“…Thus, the cyclization of 5-acetyloxyimino-4-methyliminouracil (64) in boiling ethanol gives theophylline 65 [83]. The cyclization of pyridazine [87] and pyrimidine [88] formamidoximes in the presence of dehydrating agents (e.g., PPA) leads to the formation of a new triazole ring. For example, the reaction of the oximes 66 with PPA at 70-80°C leads to the tricyclic products 67 [87].…”

“…The cyclization of pyridazine [87] and pyrimidine [88] formamidoximes in the presence of dehydrating agents (e.g., PPA) leads to the formation of a new triazole ring. For example, the reaction of the oximes 66 with PPA at 70-80°C leads to the tricyclic products 67 [87]. In the Me 3 SiN 3 /Bu 2 SnO/dioxane system the O-(ω-cyanoalkyl)oximes 68 give tetrazolyl derivatives of pyridazine oximes 69, which are used as inhibitors of aldose reductase [89].…”