Abstract:
Compounds (I), C22H20N2O2, (II), C22H20N2O2 and (III), C20H18N2O3 are the products of three-component reactions between isatoic anhydride, the corresponding amine and 3-(5-methylfuran-2-yl)- or (furan-2-yl)-2-methyl?acryl?aldehyde. Compound (I) crystallizes in the monoclinic space group P21/n, while compounds (II) and (III) are isostructural and crystallize in the ortho?rhom?bic space group Pbca. The tetra?hydro?pyrimidine ring in (I)-(III) adopts a sofa conformation. The NH nitro?gen atom has a trigonal-pyramidal geometry, whereas the N(R) nitro?gen atom is flattened. The furyl-vinyl substituents in (I)-(III) are practically planar and have an E configuration at the C=C double bond. In (I), this bulky fragment occupies the axial position at the quaternary carbon atom of the tetra?hydro?pyrimidine ring, whereas in (II) and (III) it is equatorially disposed. In the crystal of (I), mol?ecules form hydrogen-bonded chains propagating along [001] by strong inter?molecular N-H...O hydrogen bonds. The chains are packed in stacks along the a-axis direction. In the crystals of (II) and (III), mol?ecules also form hydrogen-bonded chains propagating along [100] by strong inter?molecular N-H...O hydrogen bonds. However, despite the fact that compounds (II) and (III) are isostructural, steric differences between the phenyl and furyl substituents result in chains with different geometries. Thus in the crystal of (II) the chains have a zigzag-like structure, whereas in the crystal of (III), they are almost linear. In both (II) and (III), the hydrogen-bonded chains are further packed in stacks along the b-axis direction.
