Straightforward and Regiospecific Synthesis of Pyrazole-5-carboxylates from Unsymmetrical Enaminodiketones
作者:Marcos Martins、Fernanda Rosa、Pablo Machado、Pâmela Vargas、Helio Bonacorso、Nilo Zanatta
DOI:10.1055/s-2008-1078482
日期:——
H-pyrazole-5-carboxylates was prepared from the cyclocondensation reaction of unsymmetrical enaminodiketones [RC(O)C(=CNMe 2 )C(O)CO 2 Et, where R = Ph, 4-MeOC 6 H 4 , 4-ClC 6 H 4 , 4-FC 6 H 4 , 4-O 2 NC 6 H 4 , thien-2-yl, benzofur-2-yl, CCl 3 and CF 3 ] with TERT-butylhydrazine hydrochloride or carboxymethylhydrazine. The compounds were obtained regiospecifically and in good to excellent yields (73-94%)
由不对称烯氨基二酮 [RC(O)C(=CNMe 2 )C(O)CO 2 Et, 其中 R = Ph, 4-MeOC 的环缩合反应制备了一系列 4-取代的 1 H-吡唑-5-羧酸酯6 H 4 , 4-ClC 6 H 4 , 4-FC 6 H 4 , 4-O 2 NC 6 H 4 , thien-2-yl, benzofur-2-yl, CCl 3 and CF 3 ] 与叔丁基肼盐酸盐或羧甲基肼。这些化合物是区域特异性地获得的,产率非常好(73-94%)。此外,5-羧乙基-1-(1,1-二甲基乙基)-1 H-吡唑-4-羧酸由乙基4-(2,2,2-三氯乙酰基)-1-(1, 1-二甲基乙基)-1H-吡唑-5-羧酸酯。羰基取代反应对三氯乙酰基具有区域特异性,不影响酯基。