3-(Dimethylamino)propenoate-based Regioselective Synthesis of 1,4-Disubstituted 5-Hydroxy-1H-pyrazoles
2006; Elsevier BV; Volume: 68; Issue: 5 Linguagem: Inglês
10.3987/com-06-10682
ISSN1881-0942
AutoresJurij Svete, David Kralj, Jasmin Mecinović, D. Bevk, Uroš Grošelj, Branko Stanovnik,
Tópico(s)Multicomponent Synthesis of Heterocycles
Resumo1,4-Disubstituted 5-hydroxy-1H-pyrazoles ( 9), ( 12), and (13) were prepared in two steps from hydrazines (2a-k) and 3-(dimethylamino)propenoates (1), (4), and (5).First, acid-catalyzed treatment of enaminones ( 1), (4), and ( 5) with (hetero)arylhydrazines (2a-k) afforded the corresponding dimethylamine substitution products, hydrazones (3') and enehydrazines ( 6) and ( 7).Under acidic conditions, intermediates (3'), (6), and (7) did not undergo cyclization into the pyrazole derivatives.However, heating 3', 6, and 7 in a mixture of methanol and triethylamine furnished the desired products in 65-98% yields.
Referência(s)