2,9-Dimethyl-7-phenyl-N-(4-methyl­phen­yl)dibenzo[b,h][1,6]naphthyridin-6-amine

K N Vennila; M Manoj; K Prabha; K J Rajendra Prasad; D Velmurugan

doi:10.1107/S1600536810051196

. 2010 Dec 11;67(Pt 1):o102–o103. doi: 10.1107/S1600536810051196

2,9-Dimethyl-7-phenyl-N-(4-methylphenyl)dibenzo[b,h][1,6]naphthyridin-6-amine

K N Vennila ^a, M Manoj ^b, K Prabha ^b, K J Rajendra Prasad ^b, D Velmurugan ^a,^*

PMCID: PMC3050252 PMID: 21522616

Abstract

The title compound, C₃₁H₂₅N₃, was synthesized from 6,4′,4′′-trimethyl-2,4-bis(N-phenylamino)quinoline and is the first structural example containing a phenyl and phenylamino fragment attached to a fused dibenzo[1,6]naphthyridine moiety. The fused tetracyclic ring system is essentially planar [r.m.s. deviation = 0.08 (3) Å]. The phenyl ring and the phenylamino group are inclined by 82.68 (6) and 35.31 (5)°, respectively, to the mean plane of the fused tetracyclic ring system. A weak intramolecular N—H⋯π(arene) interaction may in part influence the conformation of the molecule. In the crystal, molecules are linked by weak intermolecular C—H⋯N hydrogen bonds into centrosymmetric dimers. Additional stabilization is provided by weak C—H⋯π and π–π stacking interactions [centroid–centroid distances = 3.834 (2) and 3.898 (1) Å].

Related literature

For the biological activity of [1,6]naphthyridine derivatives, see: Ruchelman et al. (2003 ▶, 2005 ▶); Hinschberger et al. (2003 ▶); Bedard et al. (2000 ▶); Feng et al. (2008 ▶). For the synthesis of the title compound, see: Manoj & Rajendra Prasad (2009 ▶). For the crystal structures of other [1,6]naphthrydine derivatives, see: Peng et al. (2009 ▶); Sivakumar et al. (2003 ▶); Seebacher et al. (2010 ▶); Vennila et al. (2010 ▶). For bond-length data, see: Allen et al. (1987 ▶).

Experimental

Crystal data

C₃₁H₂₅N₃
M _r = 439.54
Monoclinic,
a = 11.9390 (4) Å
b = 10.5595 (4) Å
c = 19.6084 (7) Å
β = 107.369 (2)°
V = 2359.31 (15) Å³
Z = 4
Mo Kα radiation
μ = 0.07 mm⁻¹
T = 293 K
0.30 × 0.20 × 0.20 mm

Data collection

Bruker APEXII CCD diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2004 ▶) T _min = 0.982, T _max = 0.986
17909 measured reflections
2938 independent reflections
2197 reflections with I > 2σ(I)
R _int = 0.037
θ_max = 22.1°

Refinement

R[F ² > 2σ(F ²)] = 0.042
wR(F ²) = 0.132
S = 1.07
2938 reflections
310 parameters
H-atom parameters constrained
Δρ_max = 0.21 e Å⁻³
Δρ_min = −0.23 e Å⁻³

Data collection: APEX2 (Bruker, 2004 ▶); cell refinement: APEX2 and SAINT (Bruker, 2004 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: ORTEPII (Johnson, 1976) ▶; software used to prepare material for publication: SHELXL97 and PLATON (Spek, 2009 ▶).

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536810051196/lh5177sup1.cif

e-67-0o102-sup1.cif^{(24.2KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536810051196/lh5177Isup2.hkl

e-67-0o102-Isup2.hkl^{(144.2KB, hkl)}

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Table 1. Hydrogen-bond geometry (Å, °).

Cg1 and Cg2 are the centroids of the C17–C22 and C23–C28 rings, respectively.

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N3—H3⋯Cg1	0.86	2.51	3.364 (3)	174
C18—H18⋯Cg2ⁱ	0.93	2.62	3.495 (3)	156
C29—H29B⋯Cg2ⁱⁱ	0.96	2.90	3.622 (3)	133
C22—H22⋯N2ⁱⁱⁱ	0.93	2.51	3.419 (3)	166

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Symmetry codes: (i) Inline graphic ; (ii) ; (iii) .

Acknowledgments

DV acknowledges the Department of Science and Technology (DST) for providing data collection facilities under major research projects and is also thankful for financial support to the Department under the UGC–SAP and DST–FIST programs.

supplementary crystallographic information

Comment

The crystal structures of number of differently substituted naphthyridine derivatives have already been reported (e.g. Peng et al. 2009) but among those only few are dibenzo[1,6] naphthyridine compounds (e.g. Sivakumar et al. 2003; Seebacher et al., 2010). [1,6]Naphthyridine compounds are known to have biological activities (Ruchelman et al. 2005; Hinschberger et al. 2003; Feng et al., 2008). Dibenzo[1,6]naphthyridines are reported to have potent Topomerase I targeting, cytotoxic (Ruchelman et al., 2003) and are also proven anti-tumour agents. A series of [1,6] naphthyridine compounds were shown to exhibit potent activity against human cytomegalovirus (Bedard et al. , 2000). We are focused on preparing heterocyclic naphthyridine derivatives with potential biological properties. The crystal structure of the title compound is presented herein.

The molecular structure of the title compound is shown in Fig. 1 The fused tetracyclic ring system is essentially planar (r.m.s. deviation = 0.08 (3)Å) as was reported for a previously determined structure (Vennila et al., 2010). The phenyl ring and the phenyl amino group are inclined by 82.68 (6)° and 35.31 (5)°, respectively to the mean plane of the fused tetracyclic ring system. The bond lengths (Allen et al., 1987) and angles are in the normal ranges. In the crystal structure (Fig. 2), molecules are linked by weak intermolecular C-H···N hydrogen bonds into centrosymmetric dimers. Additional stabilization is provided by weak C-H···π and π–π stacking interactions.

Experimental

The synthesis follows the procedure of Manoj & Rajendra Prasad (2009). Preparation of 6,4',4''-Trimethyl-2,4-bis-(N-phenylamino)quinoline: A mixture of appropriate 2,4-dichloro-6-methylquinoline (0.010 mol) and p-toluidine (0.010 mol) was heated at 433K for half an hour. The product obtained was washed with water, dried and purified by column chromatography over silica gel and eluted with ethyl acetate : methanol mixture (95 : 5) to yield a white solid. The product was recrytallized from methanol. Preparation of 2,9,4'-Trimethyl-7-phenyl-6-(N-phenylamino) dibenzo[b,h][1,6] naphthyridine: An mixture of 6,4',4''-trimethyl-2,4-bis-(N-phenylamino) quinoline (0.0010 mol) and benzoic acid (0.0011 mol) was added to polyphosphoric acid (3 g of P₂O₅ in 1.5 mL of H₃PO₄) and kept at 323-328 K for 5 hours. The reaction was monitored by TLC. After the completion of the reaction, the reaction mixture was poured into ice water and neutralised with saturated NaHCO₃ solution to remove the excess benzoic acid. The precipitate was filtered, dried and purified by column chromatography over silica gel using petroleum ether : ethyl acetate (99 : 1) mixture to obtain yellow solid. The yellow solid was dissolved in ethylacetate and left to crystallize at 277K for about 6 months. Only few crystals were obtained and the best available was used for the X-ray structure analysis.