Crystal structures of (E)-(3-ethyl-1-methyl-2,6-di-phenyl-piperidin-4-yl-idene)amino phenyl carbonate and (E)-(3-isopropyl-1-methyl-2,6-di-phenyl-piperidin-4-yl-idene)amino phenyl carbonate

In the title compounds, C27H28N2O3, (I), and C28H30N2O3, (II), the conformation about the C=N bond is E. The piperidine rings adopt chair conformations with the attached phenyl rings almost normal to their mean planes, the dihedral angles being 85.82 (8) and 85.84 (7)° in (I), and 87.98 (12) and 86.42 (13)° in (II). The phenyl rings are inclined to one another by 52.87 (8)° in (I) and by 60.51 (14)° in (II). The main difference in the conformation of the two compounds is the angle of inclination of the phen-oxy-carbonyl ring to the piperidine ring mean plane. In (I), these two planes are almost coplanar, with a dihedral angle of 2.05 (8)°, while in (II), this angle is 45.24 (13)°. In the crystal of (I), mol-ecules are linked by C-H⋯O hydrogen bonds, forming inversion dimers with R 2 (2)(14) loops. The dimers are linked via C-H⋯π inter-actions forming a three-dimensional network. In the crystal of (II), there are no significant inter-molecular inter-actions present.