(Z)-3′,6′-Bis(diethylamino)-2-(4-oxopent-2-en-2-ylamino)spiro[isoindoline-1,9′-xanthen]-3-one

In the title compound, C33H38N4O3, the mean planes of the 9H-xanthene unit and spirolactam (nine-atom) core are almost mutually perpendicular at 87.26 (6)°. Intramolecular N—H⋯O and C—H⋯N interactions influence the 4-oxopent-2-en-2-ylamino conformation. In the crystal, weak C—H⋯O hydrogen bonds link the molecules into chains along [001].


Experimental
To a solution of 2-amino-3′,6′-bis(diethylamino)spiro [isoindoline-1,9′-xanthen]-3-one (0.50 g, 1.09 mmol) in 3 mL absolute anhydrous ethanol was added 0.5 mL pentane-2,4-dione and CAN (5% mol), then the resulting mixture was stirred at room temperature for 6 h. The reaction mixture was dissolved in 20 mL CH 2 Cl 2 , washed twice with water and dried over Na 2 SO 4 , filtered, and the filtrate was concentrated under reduced pressure. The residue was purified by column chromatography (EA:PE=1:1, v/v) to yield the title compound as a white powder (0.47 g, 80.1%). Crystals suitable for Xray analysis were obtained by slow evaporation of a solution of the title compound in ethanol at room temperature in four days.

Refinement
All the H atoms were discernible in the difference electro density maps with C-H = 0.93 and 0.96Å for aryl and methyl, respectively. U iso (H)=1.2U eq (C).

Figure 1
The structure of (I) with 35% probability displacement ellipsoids and the atom numbering scheme.

Figure 2
The crystal structure packing structure of (I).

(Z)-3′,6′-Bis(diethylamino)-2-(4-oxopent-2-en-2-ylamino)spiro[isoindoline-1,9′-xanthen]-3-one
Crystal data  Special details Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds 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 > 2sigma(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.