6-Benzyl-2-[(triphenyl-λ5-phosphanyl­idene)amino]-4,5,6,7-tetra­hydro­thieno[2,3-c]pyridine-3-carbonitrile

Hong Chen; Kai Yan

doi:10.1107/S1600536811035082

. 2011 Sep 3;67(Pt 10):o2548. doi: 10.1107/S1600536811035082

6-Benzyl-2-[(triphenyl-λ⁵-phosphanylidene)amino]-4,5,6,7-tetrahydrothieno[2,3-c]pyridine-3-carbonitrile

Hong Chen ^a,^*, Kai Yan ^b

PMCID: PMC3201343 PMID: 22058728

Abstract

In the title compound, C₃₃H₂₈N₃PS, the P atom has a distorted tetrahedral PNC₃ environment, formed by the N atom and three aryl rings. No intermolecular hydrogen-bonding interactions or π–π stacking interactions are present in the crystal structure.

Related literature

For general background to the potential use of iminophosphoranes in the synthesis of N-heterocyclic compounds by means of an aza-Wittig reaction, see: Bräse et al. (2005 ▶); Ding et al. (2005 ▶); Huang et al. (2009a ▶,b ▶); Liu et al. (2008 ▶); Palacios et al. (2007 ▶). For a related structure, see: Muller (2011 ▶).

Experimental

Crystal data

C₃₃H₂₈N₃PS
M _r = 529.61
Monoclinic,
a = 8.926 (4) Å
b = 27.537 (12) Å
c = 11.719 (5) Å
β = 101.970 (4)°
V = 2818 (2) Å³
Z = 4
Mo Kα radiation
μ = 0.20 mm⁻¹
T = 296 K
0.23 × 0.15 × 0.14 mm

Data collection

Bruker SMART CCD diffractometer
Absorption correction: multi-scan (SADABS; Sheldrick, 1996 ▶) T _min = 0.965, T _max = 0.973
25582 measured reflections
6415 independent reflections
5506 reflections with I > 2σ(I)
R _int = 0.078

Refinement

R[F ² > 2σ(F ²)] = 0.054
wR(F ²) = 0.145
S = 1.09
6415 reflections
343 parameters
14 restraints
H-atom parameters constrained
Δρ_max = 0.35 e Å⁻³
Δρ_min = −0.40 e Å⁻³

Data collection: SMART (Bruker, 1997 ▶); cell refinement: SAINT (Bruker, 1997 ▶); 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.

Supplementary Material

Crystal structure: contains datablock(s) I, global. DOI: 10.1107/S1600536811035082/aa2019sup1.cif

e-67-o2548-sup1.cif^{(25KB, cif)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536811035082/aa2019Isup2.hkl

e-67-o2548-Isup2.hkl^{(314KB, hkl)}

Supplementary material file. DOI: 10.1107/S1600536811035082/aa2019Isup3.cml

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

Acknowledgments

This work was supported financially by the Science Foundation of Hubei Province Education Department, China (project No. D20091301) and the Excellent Fund for Scientific Research and Special Projects in China Three Gorges University, China (project No. KJ2009B004).

supplementary crystallographic information

Comment

Over the past twenty years, the aza-Wittig reactions of iminophosphoranes have received increasing attention in view of their utility in the synthesis of N-heterocyclic compounds (Bräse et al., 2005; Palacios et al., 2007). Annelation of ring systems with N-heterocycles by means of an aza-Wittig reaction has been widely utilized because of the availability of functionalized iminophosphoranes. Consequently, the discovery of novel functionalized iminophosphoranes is important in this respect. Recently we have become interested in the synthesis of thienopyrimidinone, quinazolinones, and imidazolinones by an aza-Wittig reaction, with the aim of evaluating their fungicidal activities (Ding et al., 2005; Huang et al., 2009a,b; Liu et al., 2008). Meanwhile, the title compound can be used as a new precursor for obtaining of bioactive molecules with fluorescence properties. Herein we wish to report the efficient synthesis, structural characterization of the title compound.

The molecular structure of the title compound is shown in Fig.1. The molecule has a benzyl substituent at the N6 atom of the thienopyridine ring and an nitrile group substituent at C3. Within the molecule, the bond lengths and bond angles present no unusual features. In the fused thienopyridine ring system, the thiophene ring is essentially coplanar, with maximum deviation of -0.0052 and 0.0059 Å for C8 and C9, respectively. The dihedral angle between plane (N6, C5, C7) and plane (C4, C5, C7) is 61.69°. The thiophene ring forms dihedral angles of 84.67, 73.58, 2.35 and 65.29° with the adjacent 6-membered rings C12–C17, C18–C23, C24–C29 and C33–C38, respectively. Meanwhile, the P atom has a distorted PNC₃ tetrahedral environment, formed by the N atom [P═N = 1.5782 (16) Å] and three aryl rings. The crystal packing is determined by van der Waals forces. No intermolecular hydrogen bonding interaction or π-π stacking interactions are present in the crystal structure.

Experimental

A well stirred mixture of 1-benzylpiperidin-4-one (1.89 g, 10 mmol), sulfur (0.32 g, 10 mmol), malononitrile (0.66 g, 10 mmol) in EtOH (10 ml) was cooled in an ice bath and treated dropwise with Et₃N (1.01 g, 10 mmol). When addition was complete, the reaction mixture was warmed to 333 K for 40 min and then stored in the cold place until crystallization occurred. The product, 2-amino-6-benzyl-4,5,6,7-tetrahydrothieno[2,3-c]pyridine-3-carbonitrile (2.29 g, yield 85%) was recrystallized from EtOH as colourless needles, M.p. 422–423 K.

To a mixture of 2-amino-6-benzyl-4,5,6,7-tetrahydrothieno[2,3-c]pyridine-3-carbonitrile (1.35 g, 5 mmol), PPh₃ (3.94 g, 15 mmol) and C₂Cl₆ (3.55 g, 15 mmol) in anhydrous CH₃CN (40 ml), were added dropwise Et₃N (2.42 g, 24 mmol) at room temperature. The color of the reaction mixture quickly turned yellow. After stirring for 4–6 h, the solvent was removed under reduced pressure and the residue was recrystallized from EtOH to give iminophosphorane in light yellow crystals, 3.63 g (83%), M.p. 463 K; IR (KBr), cm^-1 2190 (C≡N), 1490, 1346, 1100, 688; ¹H NMR(CDCl₃, 400 MHz) δ(p.p.m.): 7.78–7.23 (m, 20H, Ar—H), 3.62 (s, 2H, Ar—CH₂), 3.24 (s, 2H, NCH₂-thiophene), 2.75 (t, J = 8.7 Hz, 2H, NCH₂CH₂), 2.64 (t, J = 8.7 Hz, 2H, NCH₂CH₂); ESI-MS (m/z): 529.2 (M⁺), 530.2 ([M+H]⁺), 531.1 ([M+2H]⁺).