Estudo cristalográfico de compostos orgânicos com potencial atividade herbicida

Abstract

Isobenzofuran-1(3H)-onas (phthalides) derivatives are an important class of compounds displaying a variety of biological effects, such as antibacterial, antioxidant, anticonvulsant, anti-HIV. Order to obtain new herbicides, five phthalides derivatives were synthesized and demonstrated the ability to inhibit the radicle growth of different species. In this work are presented the results of structural elucidation by X-ray diffraction, of five new compounds:  Compound 1: C9H8O3 6-Methoxyisobenzofuran-1(3H)-one;  Compound 2: C9H8O3 5-Methoxyisobenzofuran-1(3H)-one;  Compound 3: C8H6O3 6- hydroxy isobenzofuran-1(3H)-one;  Compound 4: C8H6O3 5- hydroxy isobenzofuran-1(3H)-one;  Compound 5: C16H16O4 3-(2-hydroxy-4,4-dimethyl-6-oxocyclohex-1- enyl)isobenzofuran-1(3H)-one. Four compounds crystallize in the monoclinic system (three in centrosymmetric space groups and one in non-centrosymmetric space group) and one crystallizes in the triclinic system. In compounds 1-4 the molecule is essentially planar with root mean-square (r.m.s) deviation to the fitted non-hydrogen atoms ranging from 0.010 Å to 0.016 Å. In compound 5, which crystallizes with two molecules per asymmetric unit, the phthalide portion is essentially planar with r.m.s. deviation for fitted atoms of 0.027 Å and 0.024 Å for molecules a and b, respectively. In the crystal packing of methoxylated compounds are present weak intermolecular interactions of the type C H···X (X =  and O). In the other hand, in the hydroxylated compounds there are strong hydrogen bonds O H···O. The compound 3 also shows weak interactions of the type C H···O. In the crystal packing of compound 5, Resonance Assisted Hydrogen Bond (RAHB) links the molecules b in an infinite polymeric network along the direction [101]. There are also C H···O and O H···O intermolecular interactions between molecules a and b of the asymmetric unit. All compounds show weak aromatic   stacking interactions.