Methyl 9-diethylamino-2,2-bis(4-methoxyphenyl)-2H-benzo[h]chromene-5-carboxylate

In the title compound, C31H29NO5, the methyl carboxylate and dimethylamino groups on the naphthopyran group are almost coplanar with the naphthopyran ring system [r.m.s. deviations = 0.08 (2) and 0.161 (2) Å, respectively]. The dihedral angle between the methyl carboxylate and dimethylamino groups is 4.9 (1)°. The pyran ring has an envelope conformation with the quaternary C atom out of plane by 0.4739 (13) Å. The methoxyphenyl substituent forms a dihedral angle of 16.6 (1)° with the plane of the benzene ring, while the other methoxyphenyl group is almost coplanar, making a dihedral angle of 1.4 (1)°.

In the title compound, C 31 H 29 NO 5 , the methyl carboxylate and dimethylamino groups on the naphthopyran group are almost coplanar with the naphthopyran ring system [r.m.s. deviations = 0.08 (2) and 0.161 (2) Å , respectively]. The dihedral angle between the methyl carboxylate and dimethylamino groups is 4.9 (1) . The pyran ring has an envelope conformation with the quaternary C atom out of plane by 0.4739 (13) Å . The methoxyphenyl substituent forms a dihedral angle of 16.6 (1) with the plane of the benzene ring, while the other methoxyphenyl group is almost coplanar, making a dihedral angle of 1.4 (1) .
Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: PK2310).

Comment
The synthesis and application of the organic photochromic and thermochromic dyes has become of great interest recently (Kumar et al., 1995;Gemert & Selvig, 2000;Nelson et al., 2002;Clarke et al. (2002); Gabbutt et al., 2003Gabbutt et al., , 2004 because of potential uses as optical transmission materials, and as ophthalmic glasses and lenses. They also have potential uses in storage technologies as optical disks or memories (Crano & Guglielmetti, 1999). In particular, benzo and naphthopyrans have been commercialized as photochromic plastic sunglasses since the early 1990s. In our group, research has been focused on the development of novel photochromic benzo and naphthopyrans (Kim et al., 2010;Do et al., 2011).

Experimental
A solution of methyl 6-dimethylamino-4-hydroxy-2-naphthoate (5 mmol) and 1,1-di(4-methoxyphenyl)-prop-2-yn-1-ol (5 mmol) in toluene (60 ml) containing acidic alumina (5 g) was refluxed for 2 hrs. The cooled solution was filtered and the alumina residue washed well with ethyl acetate (3 x 50 ml). Removal of the dried solvent gave a yellow solid which was flash chromatographed using 20% ethyl acetate in hexane as the eluent to give an off-white solid. Single crystals of the title compound suitable for X-ray diffraction were obtained by recrystallization from ethyl acetate solution.

Refinement
All H atoms were placed in calculated positions using a riding model, with C-H = 0.93 Å and U iso (H) = 1.2 U eq (C) for aromatic H atoms, C-H = 0.96 Å and U iso (H) = 1.5 U eq (C) for methyl H atoms. Fig. 1. The molecular structure of the title compound with displacement ellipsoids plotted at the 30% probability level. H atoms are presented as a small spheres of arbitary radius.