(E)-Methyl 3-(4-ethyl­phen­yl)-2-{2-[(E)-(hy­droxy­imino)­meth­yl]phen­oxy­meth­yl}acrylate

In the title compound, C20H21NO4, the two benzene rings are almost perpendicular to each other, making a dihedral angle of 86.1 (7)°. The hy­droxy­ethanimine group is essentially coplanar with the benzene ring, the largest deviation from the mean plane of the hy­droxy­ethanimine [C=N—OH] group being 0.011 (1) Å for the O atom. An intra­molecular C—H⋯O hydrogen bond occurs. The mol­ecules are linked into cyclic centrosymmetric R 2 2(6) dimers via O—H⋯N hydrogen bonds. Inter­molecular C—H⋯O hydrogen bonds link the mol­ecules, forming a C(8) chain along the a axis. The crystal packing is further stabilized by C—H⋯π inter­actions

(E)-Methyl 3-(4-chloro­phen­yl)-2-{2-[(E)-(hy­droxy­imino)­meth­yl]phen­oxy­meth­yl}acrylate

In the title compound, C18H16ClNO4, the dihedral angle between the mean planes through the aromatic rings is 83.8 (8)°. The hy­droxy­ethanimine group is essentially coplanar with the ring to which it is attached [O—N—C—C torsion angle = −177.96 (13)°]. The mol­ecules are linked into centrosymmetric R 2 2(6) dimers via O—H⋯N hydrogen bonds. The crystal packing is further stabilized by C—H⋯O inter­actions

3′-[Hy­droxy(4-oxo-4H-chromen-3-yl)meth­yl]-2-oxospiro­[indoline-3,2′-pyrrolidine]-3′-carbonitrile

In the title compound, C23H19N3O4, the pyran ring adopts a half-chair conformation, while the pyrrolidine (with a C atom as the flap atom) and the five-membered ring in the indoline (with a C atom as the flap atom) ring system adopt slight envelope conformations. The pyrrolidine ring makes dihedral angles of 83.3 (1) and 60.4 (1)° with the mean plane through all non-H atoms of the indoline and chromene ring systems, respectively. In the crystal, mol­ecules are connected by two unique N—H⋯O and O—H⋯O hydrogen-bonding inter­actions, which form centrosymmetric patterns described by graph-set motifs R 2 2(18) and R 2 2(14). These two motifs combine to form a hydrogen-bonded chain which propagates in the a-axis direction. The crystal structure is also stablized by C—H⋯O inter­actions and by aromatic π–π stacking inter­actions between the pyran and benzene rings of neighbouring mol­ecules [centroid–centroid distance = 3.755 (1) Å and slippage = 1.371 (2) Å]