1-Methyl-3-p-tolyl-3,3a,4,9b-tetra­hydro-1H-chromeno[4,3-c]isoxazole-3a-carbonitrile

Rajeswari Gangadharan; K Sethusankar; Gandhi Murugan; Manickam Bakthadoss

doi:10.1107/S1600536811021829

. 2011 Jun 18;67(Pt 7):o1695. doi: 10.1107/S1600536811021829

1-Methyl-3-p-tolyl-3,3a,4,9b-tetrahydro-1H-chromeno[4,3-c]isoxazole-3a-carbonitrile

Rajeswari Gangadharan ^a, K Sethusankar ^b,^*, Gandhi Murugan ^c, Manickam Bakthadoss ^c

PMCID: PMC3152008 PMID: 21837092

Abstract

In the title compound, C₁₉H₁₈N₂O₂, the dihedral angle between the mean planes of the fused chromeno and isoxazole units is 43.71 (7)°. The isoxazole and pyran rings exhibit envelope and half chair conformations, respectively. The crystal packing is stabilized by intermolecular C—H⋯π interactions.

Related literature

For uses of chromeno derivatives, see: Carlson (1993 ▶); Sokoloff et al. (1990 ▶) and for uses of isoxazole derivatives, see: Kozikowski (1984 ▶); Howe & Shelton (1990 ▶). For a related structure, see: Gangadharan et al. (2011 ▶). For puckering parameters, see: Cremer & Pople (1975 ▶). For bond-length and bond-angle distortions, see: Rybarczyk-Pirek et al. (2002 ▶); Allen et al. (1987 ▶); Raju et al. (2002 ▶); For the synthesis of isoxazolidines, see: Bakthadoss & Murugan (2010 ▶).

Experimental

Crystal data

C₁₉H₁₈N₂O₂
M _r = 306.35
Monoclinic,
a = 8.5344 (3) Å
b = 7.6980 (3) Å
c = 24.6017 (8) Å
β = 98.234 (2)°
V = 1599.62 (10) Å³
Z = 4
Mo Kα radiation
μ = 0.08 mm⁻¹
T = 295 K
0.30 × 0.25 × 0.25 mm

Data collection

Bruker Kappa APEXII CCD diffractometer
16796 measured reflections
3606 independent reflections
2571 reflections with I > 2σ(I)
R _int = 0.030

Refinement

R[F ² > 2σ(F ²)] = 0.042
wR(F ²) = 0.118
S = 1.04
3606 reflections
210 parameters
H-atom parameters constrained
Δρ_max = 0.16 e Å⁻³
Δρ_min = −0.14 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 ▶); software used to prepare material for publication: SHELXL97 and PLATON (Spek, 2009 ▶).

Supplementary Material

Crystal structure: contains datablock(s) global, I. DOI: 10.1107/S1600536811021829/rk2276sup1.cif

e-67-o1695-sup1.cif^{(19.9KB, cif)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536811021829/rk2276Isup2.hkl

e-67-o1695-Isup2.hkl^{(173.2KB, hkl)}

Supplementary material file. DOI: 10.1107/S1600536811021829/rk2276Isup3.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
C3—H3⋯Cg3ⁱ	0.93	2.99	3.8075 (18)	147

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Symmetry code: (i) Inline graphic .

Acknowledgments

RG and KS thank Dr Babu Varghese, SAIF, IIT, Chennai, India, for the X-ray intensity data collection.

supplementary crystallographic information

Comment

Chromenopyrroles are used in the treatment of Parkinsons disease (Carlson, 1993) and memory disorders(Sokoloff et al., 1990). Isoxazoline derivatives have been shown to be efficient precursors for many synthetic intermediates including γ-amino alchols and β-hydroxy ketones (Kozikowski, 1984). Spiroisoxazolines display interesting biological properties such as herbicidal, plant growth regulators and antitumour activities (Howe & Shelton, 1990). These observations prompted us to synthesize the title compound with fused chromeno and isoxazole rings (Bakthadoss & Murugan, 2010).

In the title molecule (Fig 1), the fused benzene and pyran rings forming the chromeno system are inclined to one another at a dihedral angle of 4.47 (7)° between the best planes of the rings. The six membered pyran ring adopts a half chair conformation with puckering amplitude Q= 0.4782 (15)Å, θ = 50.93 (17)° and φ = 278.3 (2)° (Cremer & Pople, 1975). In the pyran ring the C—C bond distances vary from a minimum of 1.3901 (19)Å to a maximum of 1.5332 (19)Å in comparison with a typical aromatic bond length of 1.384 (13)Å (Allen et al., 1987). This could be attributed to the presence of the heteroatom O1 in the cyclic system and also to the fusion of the pyran and isoxazole ring systems (Rybarczyk-Pirek et al., 2002).

The fusion between the isoxazole and the pyran rings at C7 and C8 is in cis-form. The dihedral angle between the fused chromeno and the isoxazole moieties is 43.71 (7)°.

The isoxazole ring adopts an envelope conformation at N1 with puckering parameters q2 = 0.5179 (14)Å and φ2 = 217.11 (16)° (Cremer & Pople,1975). In the isoxazole ring, enlargement of bond lengths and bond angles are observed at the points of linkages of substituents and fusion to the pyran ring (Raju et al., 2002).

The phenyl ring (C12–C17) substituent is almost perpendicular to the five membered isoxazole ring, the dihedral angle between them being 81.26 (8)°. The geometric parameters of the title compound agree well with reported structure (Gangadharan et al., 2011).

The crystal packing is stabilized by C—H···C and C—H···π interactions (C3—H···Cg3, where Cg3 is the centroid of the six membered ring defined by atoms C1–C6). The symmetry codes are: (i) x, y-1, z; (ii) -x, 1/2+y, 1/2-z. The packing view of the title compound shown in Fig. 2.

Experimental

A mixture of compound (E)-2-((2-formylphenoxy)methyl)-3-p-tolylacylonitrile (1 mmol) with N-methylhydroxylamine hydrochloride (1.1 mmol), pyridine (0.24 ml,3 mmol) and ethanol (5 ml) were placed in a round bottom flask and refluxed for 6 h. After completion of the reaction as indicated by TLC, the reaction mixture was concentrated under reduced pressure. The crude product was diluted with water (10 ml), dilute HCl (5 ml) and extracted with ethylacetate (20 ml). The organic layer was washed with brine solution (10 ml) and concentrated. The crude product was purified by column chromatography to provide the pure desired product as colourless solid.