Synthesis, spectral, crystal and theoretical studies of some novel 4-heterocyclic substituted pyrazolones
文摘
Reactions of pyrazolone ketene dithioacetals with various binucleophiles afforded 4-heterocyclic substituted pyrazolone compounds as ketene N,N-, N,O-acetals in the absence of any acid/base catalyst in good yields. The products 3a-i formed by the direct displacement of dithioacetals exhibited high regioselectivity towards binucleophiles. All the synthesized compounds were characterized by IR, 1H, 13C, 2D NMR and X-ray diffraction techniques. Optimized geometry of compound 3e has been computed by Density Functional Theory (DFT) method in B3LYP 6-31G鈭椻垪 level basis set. The title compounds 3d-f were crystallized in monoclinic space group Pc, P21/n, P21/c with cell parameters: a = 7.6647(3), b = 26.7020(8), c = 12.8364(5) 呛, 尾 = 102.842(4)掳, V = 2561.42(16) 呛3, Z = 9 (for 3d), a = 13.448(5), b = 7.539(5), c = 14.832(5) 呛, 尾 = 94.747(5)掳, V = 1498.6(12) 呛3, Z = 4 (for 3e) and a = 13.6468(17), b = 15.905(2), c = 7.9029(9) 呛, 尾 = 100.774(9)掳, V = 1685.1(4) 呛3, Z = 4 (for 3f) respectively. The spectral and crystal studies revealed that the compounds 3a-i exist in amine-one tautomeric form in solid state and the optimized structure T5 of the compound 3e exhibit good agreement with X-ray diffraction data.
