Crystal structures of N-tert-butyl-3-(4-fluoro-phenyl)-5-oxo-4-[2-(trifluoromethoxy)phenyl]-2,5-dihydrofuran-2-carboxamide and 4-(2H-1,3-benzo-dioxol-5-yl)-N-cyclohexyl-5-oxo-3-[4-(trifluoro-methyl)phenyl]-2,5-dihydrofuran-2-carboxamide

The title compounds, C₂₂H₁₉F₄NO₄, (I), and C₂₅H₂₂F₃NO₅, (II), each contain a central nearly planar dihydrofuranone ring. The r.m.s. deviation from planarity of these rings is 0.015 Å in (I) and 0.027 Å in (II). The molecules are T-shaped, with the major conformational difference being the O - C - C - O torsion angle [-178.9 (1) in (I) and 37.7 (2)° in (II)]. In the crystal of (I), molecules are linked by N - H⋯O hydrogen bonds, forming chains along [001] while in (II) molecules are linked by N - H⋯O hydrogen bonds, forming chains along [010]. In (II), the trifluoromethyl substituent is disordered over two sets of sites, with refined occupancies of 0.751 (3) and 0.249 (3).