(3-Methyl-3a,4,7,7a-tetra­hydro-5H-4,7-methano­isoxazolo[4,5-d][1,2]oxazin-5-yl)(phen­yl)methanone

Alan J Lough; Jaipal R Nagireddy; William Tam

doi:10.1107/S1600536814007740

. 2014 Apr 12;70(Pt 5):o543. doi: 10.1107/S1600536814007740

(3-Methyl-3a,4,7,7a-tetrahydro-5H-4,7-methanoisoxazolo[4,5-d][1,2]oxazin-5-yl)(phenyl)methanone

Alan J Lough ^a,^*, Jaipal R Nagireddy ^b, William Tam ^b

PMCID: PMC4011260 PMID: 24860351

Abstract

The title compound, C₁₄H₁₄N₂O₃, is the exo isomer with a syn arrangement of two O atoms in the isoxazole and oxazine rings. The dihedral angle between the isoxazole and phenyl rings is 60.38 (4)°. In the crystal, weak C—H⋯O hydrogen bonds link the molecules, forming a three-dimensional network. The isoxazole O atom is an acceptor for three of these hydrogen bonds.

Related literature

For 1,3-dipolar cycloaddition reactions of symmetrical and unsymmetrical bicyclic alkenes, see: Yip et al. (2001 ▶); Mayo et al. (2001 ▶). For a related structure, see: Lough et al. (2014 ▶).

Experimental

Crystal data

C₁₄H₁₄N₂O₃
M _r = 258.27
Orthorhombic,
a = 9.5030 (18) Å
b = 10.2912 (16) Å
c = 25.347 (5) Å
V = 2478.9 (8) Å³
Z = 8
Mo Kα radiation
μ = 0.10 mm⁻¹
T = 147 K
0.38 × 0.16 × 0.10 mm

Data collection

Bruker Kappa APEX DUO CCD diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2012 ▶) T _min = 0.671, T _max = 0.746
12134 measured reflections
2854 independent reflections
2145 reflections with I > 2σ(I)
R _int = 0.044

Refinement

R[F ² > 2σ(F ²)] = 0.041
wR(F ²) = 0.101
S = 1.03
2854 reflections
173 parameters
H-atom parameters constrained
Δρ_max = 0.28 e Å⁻³
Δρ_min = −0.20 e Å⁻³

Data collection: APEX2 (Bruker, 2012 ▶); cell refinement: SAINT (Bruker, 2012 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL2013 (Sheldrick, 2008 ▶); molecular graphics: PLATON (Spek, 2009 ▶); software used to prepare material for publication: SHELXTL (Sheldrick, 2008 ▶).

Supplementary Material

Crystal structure: contains datablock(s) I. DOI: 10.1107/S1600536814007740/is5350sup1.cif

e-70-0o543-sup1.cif^{(392.4KB, cif)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536814007740/is5350Isup2.hkl

e-70-0o543-Isup2.hkl^{(156.9KB, hkl)}

Click here for additional data file.^{(5.4KB, cml)}

Supporting information file. DOI: 10.1107/S1600536814007740/is5350Isup3.cml

CCDC reference: 995952

Additional supporting information: crystallographic information; 3D view; checkCIF report

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

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C4—H4A⋯O3ⁱ	1.00	2.50	3.2793 (18)	135
C5—H5A⋯O2ⁱⁱ	1.00	2.59	3.4017 (18)	138
C7—H7B⋯O2ⁱⁱ	0.98	2.56	3.3900 (19)	142
C7—H7C⋯O2ⁱⁱⁱ	0.98	2.60	3.568 (2)	170
C11—H11A⋯O3^iv	0.95	2.58	3.470 (2)	156

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

Acknowledgments

This work was supported by the Natural Sciences and Engineering Research Council of Canada (NSERC).

supplementary crystallographic information

1. Comment

We have previously investigated the 1,3-dipolar cycloaddition reactions of symmetrical and unsymmetrical bicyclic alkenes (Yip et al., 2001; Mayo et al., 2001). When expanding this study on N-acyl-2-oxa-3-azanorborn-5-enes, the bicyclic alkene (III) reacts (see Fig. 1) with acetonitrile oxide (II) (generated in situ) in toluene, to give the cycloadducts (IV) and (V) as regioisomers in the ratio of 70:30 respectively (ratio was determined by isolated yields). The stereochemistry and regiochemistry of the major product (IV) was determined by this single-crystal X-ray analysis. Although different stereoisomers (exo and endo) could be formed, only the exo stereoisomer was formed with a mixture of the corresponding regioisomers. The major product obtained was found to be the syn isomer (two O atoms in the rings are on the same side of the molecule).

The molecular structure of the title compound is shown in Fig. 2. The dihedral angle between the isoxazole ring [C4/C5/C6/O2/N2 with r.m.s. deviation 0.0013 Å] and the phenyl ring (C9–C14) is 60.38 (4)°. In the crystal, weak C—H···O hydrogen bonds link molecules forming a three-dimensional network (Fig. 3). The isoxazole O atom is an acceptor for three of these hydrogen bonds. We have prepared by a similar method and carried out the structure determination of a related cycloadduct (Lough et al., 2014)

2. Experimental

A solution of nitroethane (I) (126 mg, 0.579 mmol) in toluene (2 ml) was added to a flame-dried flask containing bicyclic alkene (III) (140 mg, 0.642 mmol), (BOC)₂O (233.7 mg, 1.07 mmol), DMAP (9.4 mg, 0.077 mmol) and toluene (2 ml) via a cannula over 10 minutes. The reaction mixture was stirred at room temperature for 18 h. The solvent was removed by rotary evaporation, and the crude product was purified by column chromatography (EtOAc:hexanes = 1:9 to 9:1) to obtain regiosomers (IV) and (V) in 61% and 26% respectively. A solution of isomer (IV) in EtOAc:hexanes = 1:3 gave single crystals suitable for X-ray analysis.