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Bicyclic [b]-Heteroannulated Pyridazine Derivatives. 10. Acid Cleavage of Some Beta-Keto Esters in the Reaction with 4,4-Dimethyl- and 4-Penyltetrahydropyridazine-3,6-dione 3-Hydrazones

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Wejroch K. , Karolak-Wojciechowska J. , Lange J. , Sośnicki J. G.

2002

tom Vol. 76 / nr 11

1577-1586

4,4-Dimethyltetrahydropyridazine-3,6-dione 3-hydrazone (1) reacted with _-keto esters in refluxing ethanol to give the acid cleavage products: 7,8-dihydro-3,8,8-trimethyltriazolo[ 4,3-b]pyridazin-6(5H)-one (7) and esters 9. The yield of the reaction in most cases was nearly quantitative. At room temperature mostly the simple condensation products 4 were isolated. In analogous reactions, 4-phenyltetrahydropyridazine-3,6- dione 3-hydrazone (2) was found to be much less reactive. The hydrazone-ester condensation products 4 and some 5 were converted into the corresponding pyrazolylpyridazine derivatives 10 and 11, respectively, by heating above their melting points; the formation of 7 was noted in the reactions with 4. The results support the concept of different tautomeric preferences in 1 and 2.

Synthesis of the N-Allylthioamide Derivatives of Cyclic Oxo- and Dioxo- Acids and Their Cyclization to the Derivatives of 4,5-Dihydrothiazole

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Wesołowska A. , Jagodziński T. S. , Sośnicki J. G. , Hansen P. E.

2001

tom Vol. 75, nr 3

387-400

The title N-allylthioamides (1a-f) were synthesized in the reaction of allyl isothiocyanate with enamines (1a-c) and 1,3-diketones (1d-f), respectively, carried out in an acetonitrile solution in the presence of DBU. When treated with the bromine-dioxane complex or with iodine, they underwent cyclization to the corresponding derivatives of 4,5-dihydrothiazole (2a-g). NMR spetroscopy made it possible to elucidate the tautomeric structures of the thioamides and thiazolines.

On a New Unexpected Benzoxazino-Benzoxazine Derivative

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Nowicka-Scheibe J. , Sośnicki J. G. , Grech E. , Głowiak T. , Sobczyk L.

2003

tom Vol. 77 / nr 11

1419-1426

The reaction between 2-amino-5-nitrophenol and 1,2-cyclohexanedione in ethanol leads to formation, in addition to corresponding propellane, of 3. The X-ray diffraction, NMR and IR studies allowed to solve the structure of molecules. It has been shown that planar nitrobenzoxazine groups are oriented to each other perpendicularly with a chair conformation of the cyclohexyl unit. The possible mechanism of reaction leading to 3 is discussed.