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Reaction of ethyl γ‐bromo‐β‐methoxycrotonate with carbonyl compounds. Synthesis of 4‐methoxy‐6‐substituted‐5,6‐dihydro‐2 H ‐pyran‐2‐ones and 3‐substituted 3‐pyrazolin‐5‐ones
Author(s) -
Shandala Mowafak Y.,
Ayoub Mikdad T.,
Mohammad Mouayed J.
Publication year - 1984
Publication title -
journal of heterocyclic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.321
H-Index - 59
eISSN - 1943-5193
pISSN - 0022-152X
DOI - 10.1002/jhet.5570210637
Subject(s) - chemistry , hydrazine (antidepressant) , pyran , hydrate , benzene , pyrazole , medicinal chemistry , ethanol , proton nmr , elemental analysis , carbon 13 nmr , infrared spectroscopy , organic chemistry , chromatography
Ethyl β‐methoxycrotonate I reacts with substituted carbonyl compounds II in benzene to give 4‐methoxy‐6‐substituted‐5,6‐dihydro‐2H‐pyran‐2‐ones III. The reaction of IIIa and j with hydrazine hydrate in ethanol leads to 3‐[(1′‐thienyl‐1‐hydroxy)methyl]‐5‐hydroxy‐1 H ‐pyrazole (IVa) and 3‐[1′‐styryl‐1′‐hydroxy)methyl]‐5‐hydroxy‐1 H ‐pyrazole (IVj) in good yields. The structure of the products were assigned and confirmed on the basis of their elemental analysis and the electronic absorption, infrared and nmr spectra.