β-Enaminonas, 5-hidróxi-4,5-diidropirazóis e 5-Hidróxi-4,5-diidroisoxazóis halometilsubstituídos: estudo molecular por difração de raios-x

Abstract

The molecular study by X-ray diffraction of β-aminovinyl ketones [R3C(O)CH=C(R1)N(R4R5), onde R3 = CF3, CCl3, CHCl2; R1 = H, Me; R4 = H; R5 = benzyl, Ph, 5-methylisoxazol-3-yl; R4, R5 = -(CH2)4-, -(CH2)2O(CH2)2-], methyl 5- hydroxy-5-trihalomethyl-4,5-dihydro-1H-pyrazole-1-carboxylate [3-(R1), 4-(R2), and 5- (R3) substituted, where R1 = H, Me; R2 = H, Me; R3 = CCl3, CF3], 1-cyanoacetyl-5- trifluorometyl-5-hydroxy-4,5-dihydro-1H-pyrazole [3-(R1) and 4-(R2) substituted, where R1 = H, Ph; R1, R2 = -(CH2)4-, R2 = H] and 5-triclorometyl-5-hydroxy-4,5- dihydroisoxazole [3-(R1) substituted, where R1 = Ph, 4Br-Ph, tien-2-yl] were reported. The β-aminovinyl ketones have showed the fragment O=C-C=C-N essentially plane, as well as, the heterocyclic rings 4,5-dihydropyrazole and 4,5-dihydroisoxazole. The shorter bond lengths of b-aminovinyl ketones indicated an eletronic resonance effect in the conjugated system O=C-C=C-N. This effect also was encountered in the double bond N2=C3 of the rings 4,5-dihydropyrazole and 4,5-dihydroisoxazole and the substituent of the 3-position of this rings, when this substituent was an aromatic ring. In general, the molecules studied have its crytalline packing governed by intraand intermolecular hydrogen bond.