rac-(6S)-6-Hy­droxy-6-{2-[2-(propan-2-yl­idene)hydrazinyl­idene]prop­yl}indolo[2,1-b]quinazolin-12(6H)-one

Matthew E Rodstein; Paul D Steffen; Bogdana Krivogorsky; Peter Grundt

doi:10.1107/S1600536811037408

. 2011 Sep 30;67(Pt 10):o2695–o2696. doi: 10.1107/S1600536811037408

rac-(6S)-6-Hydroxy-6-{2-[2-(propan-2-ylidene)hydrazinylidene]propyl}indolo[2,1-b]quinazolin-12(6H)-one

Matthew E Rodstein ^a, Paul D Steffen ^a, Bogdana Krivogorsky ^a, Peter Grundt ^a,^*

PMCID: PMC3201358 PMID: 22065467

Abstract

The chiral title compound, C₂₁H₂₀N₄O₂, crystallizes as a racemic mixture. In the crystal, molecules form centrosymmetric π-overlapping dimers [interplanar distance = 3.338 (6) Å], which are further connected along the a axis forming centrosymmetric dimers via O—H⋯N hydrogen bonds. C—H⋯O interactions are also observed. The indolo[2,1-b]quinazoline group is somewhat bent, with a small dihedral angle of 6.3 (4)° between the plane of the quinazoline system and the plane of the benzene ring of the indole moiety. The C=N—N=C atoms of the azine group is oriented almost perpendicular [84.1 (2)°] to the mean plane of the quinazoline system.

Related literature

The title compound is a derivative of the natural product tryptanthrin (indolo[2,1-b]quinazoline-6,12-dione). For reactions occurring at the 6-keto group of tryptanthrin with nucleophiles including CH-acidic compounds, see: Grandolini et al. (1997 ▶); Bergman & Tilstam (1985 ▶); Jao et al. (2008 ▶); Zou & Huang (1985 ▶). For related strutures, see: Brufani et al. (1971 ▶); Bergman et al. (1987 ▶); Jao et al. (2008 ▶); Grundt et al. (2010 ▶). For the Chebychev weighting scheme, see: Prince (1982 ▶); Watkin (1994 ▶).

Experimental

Crystal data

C₂₁H₂₀N₄O₂
M _r = 360.42
Monoclinic,
a = 8.6788 (17) Å
b = 15.117 (3) Å
c = 13.283 (3) Å
β = 99.58 (3)°
V = 1718.4 (6) Å³
Z = 4
Mo Kα radiation
μ = 0.09 mm⁻¹
T = 100 K
0.20 × 0.20 × 0.20 mm

Data collection

Rigaku R-AXIS RAPID II image-plate diffractometer
Absorption correction: multi-scan (ABSCOR; Higashi, 1995 ▶) T _min = 0.98, T _max = 0.98
11165 measured reflections
2914 independent reflections
1850 reflections with I > 2σ(I)
R _int = 0.096

Refinement

R[F ² > 2σ(F ²)] = 0.062
wR(F ²) = 0.161
S = 1.01
2899 reflections
244 parameters
Only H-atom displacement parameters refined
Δρ_max = 0.59 e Å⁻³
Δρ_min = −0.48 e Å⁻³

Data collection: CrystalClear (Rigaku Americas, 2009 ▶); cell refinement: HKL-2000 (Otwinowski & Minor, 1997 ▶); data reduction: CrystalClear; program(s) used to solve structure: CrystalStructure (Rigaku Americas, 2009 ▶) and SIR2004 (Burla et al., 2005 ▶); program(s) used to refine structure: CRYSTALS (Betteridge et al., 2003 ▶); molecular graphics: CAMERON (Watkin et al., 1996 ▶); software used to prepare material for publication: CRYSTALS.

Supplementary Material

Crystal structure: contains datablock(s) global, I. DOI: 10.1107/S1600536811037408/ld2027sup1.cif

e-67-o2695-sup1.cif^{(19.7KB, cif)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536811037408/ld2027Isup2.hkl

e-67-o2695-Isup2.hkl^{(145.8KB, hkl)}

Supplementary material file. DOI: 10.1107/S1600536811037408/ld2027Isup3.cml

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

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

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C20—H10⋯O18ⁱ	0.98	2.57	3.381 (6)	140 (1)
O19—H9⋯N5ⁱⁱ	0.83	2.08	2.872 (6)	160 (1)

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

Acknowledgments

This study was supported by the Stanley Medical Research Institute (grant ID 08R-2032) and the NSF (grant CHE-0922366 for X-ray diffractometer).

supplementary crystallographic information

Comment

The 6-keto group of the natural product tryptanthrin (indolo[2,1-b]quinazoline-6,12-dione) has been shown to react with numerous nucleophiles including CH-acidic compounds (Grandolini et al., 1997, Bergman & Tilstam, 1985, Jao et al., 2008, Zou & Huang, 1985). The title compound was obtained by reacting tryptanthrin with hydrazine in acetone as a solvent.

In the structure of the title compound, the azine moiety was determined to possess E-configuration in respect to the C21=N23 double bond with a trans-orientation around the N23—N24 bond (dihedral angle 158.6 (4)°). The CN double bonds of the azine moiety were found to be slighly shorter than the corresponding conjugated CN bonds in the quinazoline system. The C=O bond clearly has double bond character and was observed to be 1.226 (4) Å in length.

Experimental

1.0 mL (20 mmol) hydrazine hydrate was added dropwise to a suspension of 0.25 g (1.0 mmol) tryptanthrin in 10 mL of acetone and the reaction mixture was heated to reflux for 30 min. Upon cooling the title compound crystallized from the reaction mixture. The precipitate was collected and washed with a small amount of acetone to give 0.26 g (72%) of the title compound I. Crystals suitable for X-ray analysis were grown by slow diffusion of hexane into a solution of the title compound in ethylacetate/chloroform 1:1. The crystal was diffracted in the cold stream of an X-Stream2000 Liquid nitrogen generator with an open-flow nitrogen cryostat with a nominal stability of 0.1°K.