Crystal structure of 3-[4-(1-methylethyl)phenyl]-1-(naphthalen-2-yl)prop-2-en-1-one

The title compound, C22H20O, was synthesized by reacting 4-isopropylbenzaldehyde with 2-acetonaphtone by aldolic condensation under Claisen–Schmidt conditions. The molecule consists of a naphthalene group and a benzene ring with a pendant isopropyl moiety, both rings bound by a propenone linker. The naphthalene ring system is almost planar [maximum deviation from the least-squares plane = 0.026 (10) Å] and subtends a dihedral angle of 52.31 (4)° with the benzene ring. The propenone linker, in turn, deviates slightly more from planarity [maximum deviation = 0.125 (18) Å] and has its least-squares plane oriented midway the former two, at 25.62 (6) and 28.02 (5)° from the naphthalene ring system and the benzene ring, respectively. Finally, the isopropyl group presents its CC2 plane almost perpendicular to the benzene ring, at 85.30 (4)°. No significant hydrogen bonding or π–π stacking interactions are found in the crystal structure.


S6. Refinement
Crystal data, data collection and structure refinement details are summarized in Table 1.

S7. Comment
Chalcones are versatile and convenient intermediates for the synthesis of a wide variety of heterocyclic compounds. The enone moiety of the molecule is a favourable unit for dipolar cycloaddition with numerous reagents providing heterocyclic compounds of different ring sizes with one or several heteroatoms. Their reactions with dinucleophiles usually result in the formation of polycyclic ring systems which may be the skeleton of important heterocyclic compounds.
Among the chalcones and their analogues are especially important starting materials or intermediates for the synthesis of naturally occurring flavonoids (Geissmann, 1962;Mabry et al.,1970;Harborne, 1988Harborne, ,1994Wong, 1970) and various nitrogen-containing heterocyclic compounds. For this reason, their syntheses have been compiled and discussed in various accounts (Dhar et al., 1981;Lévai, 1997).
No significant hydrogen bonding nor π-π stacking interactions are found in the crystal structure.
supporting information

S8. Experimental
A mixture of 2-acetonaphtone (0.01 mole) and 4-isopropyl benzaldehyde (0.01 mole) was stirred in ethanol (50 ml) and then a solution of 15 ml sodium hydroxide (0.04 mole) was added drop wase. The mixture was kept for four h at room temperature and then it was poured into crushed ice and acidified with dil. HCl. The product precipitates out as solid.

S9. Refinement
H atoms were all located in a difference map, repositioned geometrically and further refined with riding constraints (C-H in the range 0.93-0.98 Å) and U iso (H) (in the range 1.2-1.5 times U eq of the parent atom)

Special details
Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes. Refinement. Refinement of F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > σ(F 2 ) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 )
x y z U iso */U eq O1