Crystal structure of 3-benzyl-2-[(E)-2-(furan-2-yl)ethen­yl]-2,3-di­hydro­quinazolin-4(1H)-one and 3-benzyl-2-[(E)-2-(thio­phen-2-yl)ethen­yl]-2,3-di­hydro­quinazolin-4(1H)-one from synchrotron X-ray diffraction

The chiral title compounds, C21H18N2O2, (I), and C21H18N2OS, (II) – products of the three-component reaction between benzyl­amine, isatoic anhydride and furyl- or thienyl-acrolein – are isostructural and form isomorphous racemic crystals. The tetra­hydro­pyrimidine ring in (I) and (II) adopts a sofa conformation. The amino N atom has a trigonal–pyramidal geometry [sum of the bond angles is 347.0° for both (I) and (II)], whereas the amido N atom is flat [sum of the bond angles is 359.3° for both (I) and (II)]. The furyl- and thienylethenyl substituents in (I) and (II) are planar and the conformation about the bridging C=C bond is E. These bulky fragments occupy the axial position at the quaternary C atom of the tetra­hydro­pyrimidine ring, apparently, due to steric reasons. In the crystals, mol­ecules of (I) and (II) form hydrogen-bonded helicoidal chains propagating along [010] by strong inter­molecular N—H⋯O hydrogen bonds.