2-[(8-Methoxycarbonyl-4b,8-dimethyl-4b,5,6,7,8,8a,9,10-octahydrophenanthren-3-yl)amino]-3,5-dinitrobenzoic acid ethyl acetate monosolvate

The title compound, C25H27N3O8·C4H8O2, has a diterpene skeleton in which the fused cyclohexane rings exhibit chair and half-chair conformations. An intramolecular C—H⋯O hydrogen bond occurs. In the crystal, N—H⋯O, O—H⋯O and C—H⋯O hydrogen bonds are observed.

supplementary materials Acta Cryst. (2012). E68, o2674 [doi:10.1107/S1600536812032278] 2-[(8-Methoxycarbonyl-4b,8-dimethyl-4b,5,6,7,8,8a,9,10-octahydrophenanthren-3-yl)amino]-3,5-dinitrobenzoic acid ethyl acetate monosolvate Bihai Tong and Ye Zhang Comment Dehydroabietic acid (DAA) is one of the isomerides in the renewable rosin. It is widely used in the fields such as paint, adhesives, printing ink (Bhatnagar, 1983), papermaking, and rubber food (Bhatnagar, 1983). Like some natural drug, it has an aromatic diterpene structure with three rings. It also has three sterogenic centres but their absolute configuration cannot be determined by this analysis. The compound comprises a reactive carboxy group and DAA molecule might be modified to obtain some multifunctional derivatives which can be used as high added value products like novel fluorescence derivatization reagents and efficient but low toxic medicines through constructing aromatic or heteroaromatic ring on DAA′ s skeleton. Methyl cis-deisopropyldehydroabietate can be easily synthesized from DAA (Fonseca et al., 2001). It provides a convenient starting material for the construction of other derivatives. Some of these derivatives lacking the isopropyl group are also antimicrobial agents (Feio et al., 1999). The molecular structure of the title compound (I) (Fig. 1), as typical of diterpenic compounds (Allen et al., 1991), shows a trans junction of rings A (defined by C16, C17, C18, C19, C20, C21) and B (defined by C11, C12, C17, C16, C15, C14) with two methyl groups in axial positions of the six membered rings. The torsion angles show a chair and a half-chair conformation for rings A and B, respectively. The overall geometry of (I) is comparable to that found for methyl dehydroabietate (Hamodrakas et al., 1978), apart from the substituted 2,4,6 -trinitrophenylamino and methylgroups at the benzene ring.

Experimental
The title compound was obtained by refluxing methyl 13-amino-cis-deisopropyldehydroabietate and 2-chloro-3, 5-dinitrobenzoic acid in ethanol in the presence of copper powder and potassium carbonate to give the title compound as a yellow precipitate in 87.7% yield. Recrystallization from ethyl acetate gave orange block-like crystals suitable for an Xray diffraction experiment. Anal.Calcd. for C 29 H 35 N 3 O 10 : C, 59.48, H, 6.02, N, 7.18%. Found:C, 58.90, H, 6.56, N, 7.00%.

Refinement
H atoms were positioned geometrically and refined using a riding model (including free rotation about the ethanol C-C bond), with C-H = 0.95-0.99 Å and with U iso (H) = 1.2 (1.5 for methyl groups) U eq (C).  The molecular structure of (I), with atom labels and 25% probability displacement ellipsoids for non-H atoms.

Figure 2
A packing diagram of the title compound, showing hydrogen bonds drawn as dashed lines.

2-[(8-Methoxycarbonyl
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.