N-(Prop-2-yn-1-yl)-1,3-benzothia­zol-2-amine

Alka Agarwal; Manavendra Kumar Singh; Suryabhan Singh; S Bhattacharya; Satish K Awasthi

doi:10.1107/S1600536811035136

. 2011 Sep 14;67(Pt 10):o2637–o2638. doi: 10.1107/S1600536811035136

N-(Prop-2-yn-1-yl)-1,3-benzothiazol-2-amine

Alka Agarwal ^a,^*, Manavendra Kumar Singh ^a, Suryabhan Singh ^b, S Bhattacharya ^b, Satish K Awasthi ^c,^*

PMCID: PMC3201401 PMID: 22065736

Abstract

In the title compound, C₁₀H₈N₂S, the 2-aminobenzothiazole and propyne groups are not coplanar [dihedral angle = 71.51 (1)°]. The crystal structure is stabilized by strong intermolecular N—H⋯N hydrogen bonds and C—H⋯C, C—H⋯π and F-type aromatic–aromatic [centroid–centroid distance = 3.7826 (12) Å] interactions are also observed.

Related literature

For the biological activity of heterocyclic compounds, see: Xuan et al. (2001 ▶) and of benzothiazole and benzimidazole compounds, see: Caroti et al. (1989 ▶); Paget et al. (1969 ▶); Da Settimo et al. (1992 ▶); Johnson et al. (2009 ▶); Kus et al. (1996 ▶). For N—H⋯N hydrogen bonding, see: Mingos & Braga (2004 ▶). For F-type aromatic–aromatic interactions, see: Zhang et al. (2010 ▶). For details of the synthesis, see: Lilienkampf et al. (2009 ▶). For recently reported small crystal structures and their antimicrobial activity, see: Singh, Agarwal & Awasthi (2011 ▶); Singh, Agarwal, Mahawar & Awasthi (2011 ▶); Awasthi et al. (2009 ▶). graphic file with name e-67-o2637-scheme1.jpg

Experimental

Crystal data

C₁₀H₈N₂S
M _r = 188.25
Monoclinic,
a = 6.8048 (4) Å
b = 8.6071 (5) Å
c = 15.8244 (8) Å
β = 99.445 (5)°
V = 914.26 (9) Å³
Z = 4
Mo Kα radiation
μ = 0.30 mm⁻¹
T = 293 K
0.40 × 0.39 × 0.38 mm

Data collection

Oxford Diffraction Xcalibur Eos diffractometer
Absorption correction: multi-scan (CrysAlis PRO; Oxford Diffraction, 2009 ▶) T _min = 0.771, T _max = 1.000
4188 measured reflections
2454 independent reflections
1428 reflections with I > 2σ(I)
R _int = 0.045

Refinement

R[F ² > 2σ(F ²)] = 0.043
wR(F ²) = 0.131
S = 0.88
2454 reflections
128 parameters
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.17 e Å⁻³
Δρ_min = −0.27 e Å⁻³

Data collection: CrysAlis PRO (Oxford Diffraction, 2009 ▶); cell refinement: CrysAlis PRO; data reduction: CrysAlis PRO; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: Mercury (Macrae et al., 2006 ▶); software used to prepare material for publication: publCIF (Westrip, 2010 ▶).

Supplementary Material

Crystal structure: contains datablock(s) I, global. DOI: 10.1107/S1600536811035136/zj2020sup1.cif

e-67-o2637-sup1.cif^{(15.3KB, cif)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536811035136/zj2020Isup2.hkl

e-67-o2637-Isup2.hkl^{(100KB, hkl)}

Supplementary material file. DOI: 10.1107/S1600536811035136/zj2020Isup3.cml

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

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

Cg1 is the centroid of the S1,C1,C6,N1,C7 ring.

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N2—HN2⋯N1ⁱ	0.87 (3)	2.05 (3)	2.910 (2)	170 (2)
C8—H8A⋯C4ⁱⁱ	0.98	2.86	3.756 (3)	153 (1)
C10—H10⋯C1ⁱⁱⁱ	0.89	2.87	3.687 (3)	153 (1)
C10—H10⋯C6ⁱⁱⁱ	0.89	2.89	3.776 (3)	174 (1)
C10—H10⋯Cg1ⁱⁱⁱ	0.89	2.74	3.548 (3)	151

Open in a new tab

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

Acknowledgments

AA and MKS are thankful to the University Grant Commission (scheme No. 34–311/2008), New Delhi, and Banaras Hindu University (BHU), Varanasi, India, respectively, for financial assistance. The authors are highly thankful to the department of Chemistry, Banaras Hindu University, for providing the single-crystal X-ray data.

supplementary crystallographic information

Comment

Heterocyclic compounds containing nitrogen, sulfur, oxygen etc have immense importance especially in pharmaceutical industry. Most of the modern drugs contain one or more heteroatom in their scaffold. Further, oxidation of nitrogen in heterocycle plays key role in bioactivity of these scaffolds (Xuan, et al., 2001). It is well documented that benzothiazole and benzimidazole derivatives show wide range of biological activities including antilipidemic (Caroti, et al., 1989), antimicrobial (Kus, et al., 1996), antiviral (Paget, et al., 1969) anti-inflammatory and analgesic properties (Da Settimo, et al., 1992). Moreover, 2-aminobenzimidazole/benzothiazole derivatives are common intermediate for the synthesis of various drugs. Anticancer properties of benzothiazole derivatives in cell based assays are also well documented (Johnson, et al., 2009).Our research interest involves the antimicrobial activities of small molecule (Awasthi, et al., 2009). Recently, we have reported several small crystal structures (Singh, Agarwal & Awasthi 2011, Singh, Agarwal, Mahawar et al., 2011). We report here the crystal structure of N-(prop-2-yn-1-yl)-1,3-benzothiazol-2-amine (Figure 1).

In the title compound, the C7—N2 single bond (1.342 Å) is shorter than normal C—N bond (1.47 Å) suggesting a delocalized double bond in benzothiazole moiety. Further, N2—C8 bond (1.438 Å) is also shorter than a standard C—N bond distance due to delocalization of electrons. Again, it is evident from the crystal structure that the title compound is stabilized by strong intermolecular N—H···N hydrogen bonding as well as C—H···π interactions and aromatic π···π stacking interaction resulting in the formation of supramolecular arrangement in the cystal as seen in the crystal packing along b axis (Figure 2, Table 1). The intermolecular hydrogen bond distance between N2···N1 (2.91 Å) is shorter than N···N average bond range 3.15 Å, suggesting strong hydrogen bonding (Mingos & Braga, 2004).

In the cystal packing two benzothiazole skeletons are arranged in an antiparallel fashion by F-type aromatic–aromatic interactions and form a dimer, the ring A and C of an benzothiazole skeleton stacks with the ring C and A of another adjacent benzothiazole skeleton, respectively. The distance of CgA and CgC is 3.783 Å, where CgA and CgC are the center of ring A and C, respectively and the centroid - centroid distance between two adjacent benzothiazole ring is 3.879Å (Zhang et al., 2010). 2-Aminobenzothiazole and propyne group are not co-planar with a dihedral angle of 71.51°. The torsion angles of C7—N2—C8—C9 and C10—C9—C8—N2 are found 91.1 (3) and 44 (7)° respectively. The CCDC No. of the crystal is 806158.

Experimental

The synthesis of the title compound was carried out according to the published procedure (Lilienkampf, et al., 2009). Briefly, to a solution of 2-aminobenzothaizole (0.90 g, 6 mmol) in dry acetone was added anhydrous K₂CO₃ (4.97 g m, 32 mmol) and reaction mixture was further refluxed for 15–30 minutes. Subsequently, KI (0.50 g m, 3 mmol) and propargyl bromide (0.64 ml, 7.2 mmol) were added and further refluxed the reaction mixture for 18 hrs. The reaction mixture was cooled, filtered, and the filtrate was evaporated in vacuo to give the product which was purified by column chromatography using hexane and dichloromethane (65:35) as eluent. The product was crystallized from hexane:dichloromethane (1:1). The light pink colored crystals were obtained by slow evaporation of solvent at room temperature in several days. Yield = 20%. MS (Macromass G) m/z = 188 (M⁺), R_f = 0.59 (98:2, CH₂Cl₂: MeOH), m.p.= 215°, Elemental analysis (Perkin –Elmer 240 C elemental analyzer) Calculated for: C₁₀H₈N₂S (%) C– 63.8, H-4.2, N -14.9, S-17.1, found C-63.9, H-4.5, N -14.7, S-16.9. ¹H NMR (CDCl₃), 8.35 (s, 1H, NH), 7.71–7.68 (m, 1H), 7.44–7.42(m, 1H), 7.26–7.21 (m, 1H), 7.07–7.02(m, 1H), 4.18–4.17(m, 2H, CH₂) 3.21 (s, 1H, CH).