2-Isobutyl-6-phenyl­imidazo[2,1-b][1,3,4]thia­diazole

Hoong-Kun Fun; Madhukar Hemamalini; D Jagadeesh Prasad; Prakash Anil Castelino; V V Anitha

doi:10.1107/S1600536810053201

. 2011 Jan 8;67(Pt 2):o254. doi: 10.1107/S1600536810053201

2-Isobutyl-6-phenylimidazo[2,1-b][1,3,4]thiadiazole

Hoong-Kun Fun ^a,^*,^‡, Madhukar Hemamalini ^a, D Jagadeesh Prasad ^b, Prakash Anil Castelino ^c, V V Anitha ^b

PMCID: PMC3051612 PMID: 21522948

Abstract

In the title compound, C₁₄H₁₅N₃S, the imidazo[2,1-b][1,3,4]thiadiazole fused-ring system is close to planar, with a maximum deviation of 0.042 (1) Å, and the dihedral angle between it and the phenyl ring is 24.21 (6)°. The isobutyl group is disordered over two sets of sites in a 0.899 (9):0.101 (9) ratio. In the crystal, weak aromatic π–π stacking interactions involving the imidazole and thiadiazole rings with a centroid–centroid distance of 3.8067 (7) Å occur.

Related literature

For applications of imidazo [2,1-b]-1,3,4-thiadiazole derivatives, see: Terzioglu & Gursoy (2003 ▶); Kolavi et al. (2006 ▶); Gadad et al. (2000 ▶); Andotra et al. (1997 ▶); Khazi et al. (1996 ▶); Andreani et al. (1982 ▶, 1987 ▶, 1991 ▶); Eberle & Robert (1977 ▶).

Experimental

Crystal data

C₁₄H₁₅N₃S
M _r = 257.35
Monoclinic,
a = 5.6921 (1) Å
b = 19.6453 (4) Å
c = 12.3610 (2) Å
β = 96.127 (1)°
V = 1374.35 (4) Å³
Z = 4
Mo Kα radiation
μ = 0.22 mm⁻¹
T = 296 K
0.65 × 0.48 × 0.25 mm

Data collection

Bruker SMART APEXII CCD diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2009) ▶ T _min = 0.870, T _max = 0.947
36499 measured reflections
4038 independent reflections
3378 reflections with I > 2σ(I)
R _int = 0.028

Refinement

R[F ² > 2σ(F ²)] = 0.039
wR(F ²) = 0.115
S = 1.03
4038 reflections
191 parameters
3 restraints
H-atom parameters constrained
Δρ_max = 0.31 e Å⁻³
Δρ_min = −0.30 e Å⁻³

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

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536810053201/hb5776sup1.cif

e-67-0o254-sup1.cif^{(20.2KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536810053201/hb5776Isup2.hkl

e-67-0o254-Isup2.hkl^{(197.9KB, hkl)}

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

Acknowledgments

HKF and MH thank the Malaysian Government and Universiti Sains Malaysia for the Research University grant No. 1001/PFIZIK/811160. MH also thanks Universiti Sains Malaysia for a post-doctoral research fellowship.

supplementary crystallographic information

Comment

Imidazo [2,1-b]-1,3,4-thiadiazole derivatives are found to be biological active compounds possessing anticancer (Terzioglu & Gursoy, 2003), antitubercular (Kolavi et al., 2006), antibacterial (Gadad et al., 2000), antifungal (Andotra et al., 1997), anticonvulsant, analgesic (Khazi et al., 1996), anti-inflammatory (Andreani et al., 1982), diuretic (Andreani et al., 1991) and herbicidal activities (Andreani et al., 1991). Moreover 1,3,4-thiadiazoles have many interesting biological activities, for example, 2-amino-5-(trifluoromethylphenyl alkyl)-1,3,4 thidadiazoles were used in the treatment of insomnia and anxiety (Eberle & Robert, 1977).

The title compound is shown in Fig. 1. The imidazo[2,1-b] [1,3,4]thiadiazole (S1/N1–N3/C7–C10) ring is essentially planar, with a maximum deviation of 0.042 (1) Å for atom C7. The isobutyl group is disordered over two sets of positions, with a refined occupancy ratio of 0.899 (9):0.101 (9). The dihedral angle between the imidazo[2,1-b] [1,3,4]thiadiazole (S1/N1–N3/C7–C10) ring and the benzene ring (C1–C6) is 24.21 (6)°.

In the crystal structure (Fig. 2), there are no classical hydrogen bonds and stabilization is achieved by weak π–π stacking interactions between the thiadiazole (S1/N2–N3/C8–C9) ring and imidazole (N1–N2/C7–C8/C10) ring with centroid-to-centroid distance of 3.8067 (7) Å [symmetry code: 2-x, -y, 2-z].

Experimental

5-isobutyl-1,3,4-thiadiazole-2-amine (1 molar equivalent) and phenacyl bromide (1 molar equivalent) are refluxed with ethanol for 4 hrs. The solvent was then distilled off and the reaction mass was poured into the crushed ice. The resulting solid, 2-isobutylimidazo[2,1-b][1,3,4]thiadiazole, that separated out was filtered and dried. The compound was recrystallized using ethanol and DMF mixture to form yellow blocks of the title compound. M.pt. 121–126°C.