24,4,8-Trioxa-21-aza-1,3,6(1,2)-tri­benzena-2(2,3)-bicyclo­[3.3.0]octa­na­cyclo­octa­phane

P R Seshadri; B Balakrishnan; K Ilangovan; S Purushothaman; R Raghunathan

doi:10.1107/S160053680900720X

. 2009 Mar 6;65(Pt 4):o670. doi: 10.1107/S160053680900720X

2⁴,4,8-Trioxa-2¹-aza-1,3,6(1,2)-tribenzena-2(2,3)-bicyclo[3.3.0]octanacyclooctaphane

P R Seshadri ^a,^*, B Balakrishnan ^b, K Ilangovan ^c, S Purushothaman ^d, R Raghunathan ^d

PMCID: PMC2968892 PMID: 21582414

Abstract

The crystal structure of the title compound, C₂₆H₂₅NO₃, was determined as part of an investigation of host–guest and electron donor–acceptor complexes. The oxazole and the pyrrole rings both adopt envelope conformations. The dihedral angle between the two benzene rings directly linked to the oxazole ring is 49.5 (1)°. The crystal structure is stabilized by a C—H⋯π interaction.

Related literature

For biological properties of azomethine ylides, see: Chiacchio et al. (2003 ▶). For general background, see: Diederich (1991 ▶); Cram & Cram (1994 ▶); Morrison & Hoger (1996 ▶); Padwa (1984 ▶). For reference bond-length data, see: Allen et al. (1987 ▶).For puckering and asymmetry parameters, see: Cremer & Pople (1975 ▶); Nardelli (1983 ▶).

Experimental

Crystal data

C₂₆H₂₅NO₃
M _r = 399.47
Monoclinic,
a = 31.1942 (7) Å
b = 8.3992 (2) Å
c = 16.0323 (4) Å
β = 101.468 (1)°
V = 4116.70 (17) Å³
Z = 8
Mo Kα radiation
μ = 0.08 mm⁻¹
T = 293 K
0.25 × 0.20 × 0.20 mm

Data collection

Bruker Kappa APEXII area-detector diffractometer
Absorption correction: multi-scan (SADABS; Sheldrick, 2001 ▶) T _min = 0.979, T _max = 0.983
22005 measured reflections
5004 independent reflections
2790 reflections with I > 2σ(I)
R _int = 0.029

Refinement

R[F ² > 2σ(F ²)] = 0.059
wR(F ²) = 0.213
S = 1.03
5004 reflections
271 parameters
H-atom parameters constrained
Δρ_max = 0.40 e Å⁻³
Δρ_min = −0.22 e Å⁻³

Data collection: APEX2 (Bruker, 2004 ▶); cell refinement: 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: ORTEP-3 (Farrugia, 1997 ▶) and PLATON (Spek, 2009 ▶); software used to prepare material for publication: SHELXL97 and PLATON.

Supplementary Material

Crystal structure: contains datablocks I, global. DOI: 10.1107/S160053680900720X/wn2311sup1.cif

e-65-0o670-sup1.cif^{(23.6KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S160053680900720X/wn2311Isup2.hkl

e-65-0o670-Isup2.hkl^{(240.2KB, hkl)}

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
C7—H7A⋯Cg1ⁱ	0.97	2.94	3.827 (3)	153

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Symmetry code: (i) Inline graphic . Cg1 is the centroid of the C1–C6 ring.

Acknowledgments

BB thanks Dr Babu Varghese, SAIF, IIT-Madras, India, for his help with the data collection.

supplementary crystallographic information

Comment

The design and synthesis of cyclophanes possessing rigidly defined cavities and shape-persistent structures of molecular dimensions is of interest as molecular hosts in the areas of host-guest and electron donor-acceptor complexes (Diederich, 1991; Cram & Cram, 1994; Morrison & Hoger, 1996). 1,3-Dipolar cycloaddition reactions afford efficient methods for the construction of heterocyclic units in a highly regio- and stereoselective manner (Padwa, 1984). In particular, the chemistry of azomethine ylides has gained significance in recent years as it serves as an expedient route for the construction of nitrogen heterocycles. N and O heterocycles have also been shown to provide useful information about anticancer and antiviral properties (Chiacchio et al., 2003).

In the crystal structure of the title compound, the oxazole ring adopts an envelope conformation with atom C15 displaced by 0.172 (3) Å from the plane of the other ring atoms N1/O3//C14/C19. The puckering parameters (Cremer & Pople, 1975) and asymmetry parameters (Nardelli, 1983) are q₂ =0.275 (2) Å, φ = 152.3 (5)°, Δ_S(C15) = 5.7 (2)° and Δ₂(C19) = 8.5 (2)°. The pyrrole ring also adopts an envelope conformation with atom C18 displaced by 0.208 (3) Å from the plane of the other ring atoms C15/C16/C17/N1. The puckering parameters (Cremer & Pople, 1975) and asymmetry parameters (Nardelli, 1983) are q₂= 0.329 (3) Å, φ = 144.0 (6)°, Δ_S(C18) = 0.9 (4)° and Δ₂(C16) = 16.5 (4)°.

The conformation of the cyclophane ring O1/ C7/ C6/ C1/ C26/ O2/ C21/ C20/ C19/ C14/ C13/ C8 is described by the torsion angles in Table 1. The dihedral angle between the two benzene rings directly linked to the oxazole ring is 49.5 (1)°. The bond lengths (Allen et al., 1987) and bond angles are in agreement with the values reported in literature.

The crystal structure is stabilized by a C—H···π (C7—H7A···Cg1) interaction, where Cg1 is the centroid of the C1—C6 ring.

Experimental

To a solution of O,O'-coupled salicylaldehyde (bis aldehyde), using o-xylylene bromide (2 mmol) in dry acetonitrile (20 ml), was added L-proline (1 mmol) under an N₂ atmosphere. The reaction was refluxed for 4 h. After completion of the reaction, the solvent was distilled off under reduced pressure and the crude product was purified by column chromatography.