114658-00-3Relevant articles and documents
C-C bond cleavage studies in bipyrazoles: A convenient synthesis of pyrazolo-5-ols
Singh, Shiv P.,Naithani, Rajesh,Aggarwal, Ranjana,Prakash, Om
, p. 611 - 619 (2007/10/03)
The treatment of 4-acetoacetyl derivative (3) of the pyrazoles with hydrazines in ethanol/HCl furnished a variety of bipyrazoles (4). However, when the reaction was performed in sodium acetate/acetic acid/ethanol, different hydrazines gave different products. Under these conditions an unexpected C-C bond cleavage was observed thus affording a convenient route for the formation of pyrazolo-5-ols (5 and 6).
Synthesis of Pyranopyrazol-4(1H)-ones and -4(2H)-ones from Dehydroacetic Acid. Homo- and Heteronuclear Selective NOE Measurements for Unambiguous Structure Assignment
Cantos, Albert,March, Pedro de,Moreno-Manas, Marcial,Pla, Anna,Sanchez-Ferrando, Francisco,Virgili, Albert
, p. 4425 - 4432 (2007/10/02)
Cyclization of dehydroacetic acid N-substituted hydrazones furnished 1-substituted 3,6-dimethylpyranopyrazol-4(1H)-ones, together with varying amounts of N,N'-disubstituted 5-hydroxy-3-methyl-4-(3-methyl-1H-pyrazol-5-yl)-1H-pyrazoles.The same pyranopyrazolones were obtained regioselectively without side reactions from N-alkylhydrazines and 4-chloro-3-(1-chlorovinyl)-6-methyl-2H-pyran-2-one, ("Dehydroacetchlorid"), while N-arylhydrazines gave the 2-aryl-3,6-dimethylpyranopyrazol-4(2H)-ones.NMR NOE methods, including long-range selective heteronuclear 13C NOE enhancement measurements, allowed unambiguous between -4(1H)-ones and -4(2H)-ones.
