Crystal structure of racemic (R/S,E)-2-(4-hy-droxy-phen-yl)-4-(2-phenyl-hydrazin-1-yl-idene)chromane-5,7-diol ethanol monosolvate.

Hemant P Yennawar,Anna Sigmon

doi:10.1107/s2056989022002079

Abstract

The crystal structure of racemic (R/S,E)-2-(4-hy-droxy-phen-yl)-4-(2-phenyl-hydrazin-1-yl-idene)chromane-5,7-diol ethanol monosolvate, C21H18N2O4·C2H6O, in a centrosymmetric lattice is reported. The two racemates occupy the same position in the asymmetric unit - a disordered mixed enanti-omeric structure. Hydrogen bonds of the type O-H⋯C(π) in addition to typical C-H⋯O, O-H⋯O and O-H⋯N are identified. A positional disorder is seen in the solvent mol-ecule (ethanol) as well. The phenyl-hydrazone group is nearly coplanar with the chromane ring system [dihedral angle = 15.5 (1)°], while the the 4-hy-droxy-phenyl ring is perpendicular [dihedral angle = 87.2 (1)°] to the chromane. The pyran ring has an envelope pucker [Q = 0.363 (3) Å, θ = 57.6 (3)°; and for the enanti-omer: Q = 0.364 (3) Å, θ = 127.4 (4)°].

Highlights

Naringenin is a naturally occurring flavanone compound found in citrus fruits, bergamot and tomatoes (Cai et al, 2004)
Crystal structures have not been reported to date of any hydrazone derivatives of naringenin
The phenylhydrazone group is nearly coplanar with the chromane ring system [dihedral angle = 15.5 (1)], while the the 4-hydroxyphenyl ring is perpendicular [dihedral angle = 87.2 (1)] to the chromane

Summary

Chemical context

Naringenin is a naturally occurring flavanone compound found in citrus fruits, bergamot and tomatoes (Cai et al, 2004). The title compound, (R/S,E)-2-(4-hydroxyphenyl)-4-(2phenylhydrazineylidene)chromane-5,7-diol, is a hydrazone naringenin derivative that has been reported to induce apoptosis in human cervical cancer cells (Kim et al, 2012). 5-hydroxy-7,40-diacetyloxyflavanoneN-phenylhydrazone, exhibits cytotoxicity against non-smallcell lung cancer cells (Bak et al, 2011). Despite their biological value, crystal structures have not been reported to date of any hydrazone derivatives of naringenin. The pyran ring has an envelope pucker [Q = 0.363 (3) A , = 57.6 (3); and for the enantiomer: Q = 0.364 (3) A , = 127.4 (4)]. An intramolecular O—HÁ Á ÁN hydrogen bond exists between one of the hydroxy groups on the chromane ring and the nitrogen of the hydrazone group (Table 1).

Structural commentary

Supramolecular features

Database survey

Synthesis and crystallization

Refinement