3-Phenyl-1H-pyrrolo[2,1-c][1,4]oxazin-1-one

The mol­ecule of the title compound, C₁₃H₉NO₂, is slightly twisted with a dihedral angle of 4.85 (9)° between the nine-membered ring system and the phenyl ring. The nine non-H atoms of the 1H-pyrrolo[2,1-c][1,4]oxazin-1-one system are coplanar [r.m.s. deviation = 0.0122 (2) Å]. In the crystal, weak inter­molecular C—H...O inter­actions link mol­ecules into chains along [10]. The crystal studied was an inversion twin with a 0.48624 (9):0.51376 (9) domain ratio.

Key indicators

• Single-crystal X-ray study
• T = 113 K
• Mean [sigma](C-C) = 0.003 Å
• R factor = 0.031
• wR factor = 0.085
• Data-to-parameter ratio = 8.3

checkCIF/PLATON results

No syntax errors found



Alert level C
PLAT910_ALERT_3_C Missing # of FCF Reflections Below Th(Min) .....          2
PLAT911_ALERT_3_C Missing # FCF Refl Between THmin & STh/L=  0.600          2

Alert level G
REFLT03_ALERT_4_G Please check that the estimate of the number of Friedel pairs is
            correct. If it is not, please give the correct count in the
            _publ_section_exptl_refinement section of the submitted CIF.
           From the CIF: _diffrn_reflns_theta_max           26.99
           From the CIF: _reflns_number_total               1222
           Count of symmetry unique reflns         1225
           Completeness (_total/calc)             99.76%
           TEST3: Check Friedels for noncentro structure
           Estimate of Friedel pairs measured         0
           Fraction of Friedel pairs measured     0.000
           Are heavy atom types Z>Si present         no

   0 ALERT level A = In general: serious problem
   0 ALERT level B = Potentially serious problem
   2 ALERT level C = Check and explain
   1 ALERT level G = General alerts; check

   0 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   0 ALERT type 2 Indicator that the structure model may be wrong or deficient
   2 ALERT type 3 Indicator that the structure quality may be low
   1 ALERT type 4 Improvement, methodology, query or suggestion
   0 ALERT type 5 Informative message, check

---

S1. Comment

A series of pyrrolo[1,2-a]pyrazine compounds show potent and selective non-competitive mGluR5 antagonists properties (Micheli et al., 2008). We previously reported the synthesis and crystal structure of 3-methyl-1H-pyrrolo[2,1-c][1,4]oxazin-1-one (I) (Khan et al., 2010). The title compound (II), which was designed by changing the methyl substituent in (I) to phenyl, is a new key intermediate which can be used as a precursor for the syntheses of muscle relaxant agents (Bélanger et al., 1983) and other biological active compounds (Fu et al., 2002).

The molecule of title compound (Fig. 1) is slightly twisted, the dihedral angle between this nine membered ring system and phenyl ring being 4.85 (9)° and the O1–C6–C8–C9 torsion angle 5.0 (3)°. The nine non-hydrogen atoms of the 1H-pyrrolo[2,1-c][1,4]oxazin-1-one ring system are coplanar with a r.m.s. of 0.0122 (2) Å. The bond lengths are in normal ranges (Allen et al., 1987) and comparable with the related structure (Khan et al., 2010). In the crystal structure (Fig. 2), weak intermolecular C—H···O interactions (Table 1) link the molecules into chains along [110]. These chains are stacked along the b axis.

Related literature

For the biological activity and applications of pyrrolo[1,2-a]pyrazine derivatives, see: Bélanger et al. (1983); Fu et al. (2002); Micheli et al. (2008). For a related structure, see: Khan et al. (2010). For standard bond-length data, see: Allen et al. (1987).

S2. Experimental

A solution of α-bromo acetophenone (2.37 g, 11.91 mmol) in acetone (25 ml) was dropwise added through a dropping funnel to a slurry of 2,2,2-trichloro-1-(lH-pyrrol-2-yl)ethanone (1.69 g, 7.95 mmol), potassium carbonate (1.98 g, 14.31 mmol) and acetone (20 ml) at room temperature in a 100 ml reaction flask. The reaction mixture was refluxed for 4 h. The solid was then removed by filtration and washed with acetone. The filtrate was concentrated under reduced pressure by rotary evaporator, the residue was partitioned between water (20 ml) and ethyl acetate (40 ml) in a separatory funnel (100 ml). The organic layer was separated and the aqueous phase was washed with ethyl acetate (30 ml x 2). The combined organic layers were washed successively with water (20 ml x 3) and brine solution and dried over anhydrous MgSO₄. After filtration, the solvent was removed by rotary evaporator to obtain the oily residue (1.90 g) which was purified by flash column chromatography (petroleum ether:ethyl acetate, 4:1 v/v) to afford the desired compound as white solid (1.05 g, yield 62.5 %). Colourless needle-shaped single crystals of the title compound suitable for X-ray structure determination were recrystalized from ethyl acetate by slow evaporation of the solvent at room temperature after several days.

S3. Refinement

H atoms were placed in calculated positions with C—H = 0.95 Å, and were included in the refinement in a riding-model approximation, with U_iso(H) = 1.2 U_eq(C). The highest residual electron density peak and the deepest hole are located at 0.69 Å and 0.93 Å from atom C4. The crystal studied was an inversion twin, with a refined BASF ratio of 0.48624 (9)/0.51376 (9). The final refinement was carried out with Friedel pairs merged.

Computing details

Data collection: CrystalClear (Rigaku, 2005); cell refinement: CrystalClear (Rigaku, 2005); data reduction: CrystalClear (Rigaku, 2005); program(s) used to solve structure: SHELXTL (Sheldrick, 2008); program(s) used to refine structure: SHELXTL (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008) and PLATON (Spek, 2009).

Figures

	Fig. 1. The molecular structure of the title compound, showing 50% probability displacement ellipsoids and the atom-numbering scheme.
	Fig. 2. The crystal packing of the title compound viewd along the b axis. Intermoilecular C—H···O interactions are drawn as dashed lines.

3-Phenyl-1H-pyrrolo[2,1-c][1,4]oxazin-1-one

Crystal data

C13H9NO2	F(000) = 220
Mr = 211.21	Dx = 1.434 Mg m^−3
Monoclinic, P21	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2yb	Cell parameters from 1222 reflections
a = 5.870 (1) Å	θ = 2.8–27.0°
b = 3.8345 (7) Å	µ = 0.10 mm^−1
c = 21.733 (4) Å	T = 113 K
β = 91.059 (7)°	Needle, colourless
V = 489.09 (15) Å^3	0.22 × 0.18 × 0.08 mm
Z = 2

Data collection

Rigaku Saturn CCD area-detector diffractometer	1222 independent reflections
Radiation source: rotating anode	1092 reflections with I > 2σ(I)
Multilayer monochromator	Rint = 0.032
Detector resolution: 14.63 pixels mm^-1	θmax = 27.0°, θmin = 2.8°
ω and φ scans	h = −7→7
Absorption correction: multi-scan (CrystalClear; Rigaku, 2005)	k = −4→4
Tmin = 0.979, Tmax = 0.992	l = −26→27
4358 measured reflections

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F^2 > 2σ(F^2)] = 0.031	H-atom parameters constrained
wR(F^2) = 0.085	w = 1/[σ^2(Fo^2) + (0.050P)^2] where P = (Fo^2 + 2Fc^2)/3
S = 1.10	(Δ/σ)max < 0.001
1222 reflections	Δρmax = 0.20 e Å^−3
147 parameters	Δρmin = −0.19 e Å^−3
1 restraint	Extinction correction: SHELXTL (Sheldrick, 2008), Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.037 (9)

Special details

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.

Refinement. Refinement of F² against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F², conventional R-factors R are based on F, with F set to zero for negative F². The threshold expression of F² > σ(F²) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F² are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
O1	0.4797 (2)	0.4846 (4)	0.25405 (5)	0.0201 (4)
O2	0.7147 (2)	0.7726 (4)	0.31664 (6)	0.0273 (4)
N1	0.1877 (2)	0.3508 (4)	0.34783 (7)	0.0181 (4)
C1	0.0686 (3)	0.3143 (6)	0.40070 (8)	0.0219 (5)
H1	−0.0763	0.2067	0.4044	0.026*
C2	0.1959 (3)	0.4614 (6)	0.44782 (8)	0.0232 (5)
H2	0.1546	0.4700	0.4899	0.028*
C3	0.3965 (3)	0.5960 (6)	0.42329 (9)	0.0230 (5)
H3	0.5148	0.7140	0.4453	0.028*
C4	0.3895 (3)	0.5244 (5)	0.36106 (8)	0.0186 (4)
C5	0.5406 (3)	0.6064 (6)	0.31182 (8)	0.0198 (4)
C6	0.2775 (3)	0.3039 (6)	0.24323 (8)	0.0177 (4)
C7	0.1330 (3)	0.2396 (6)	0.28844 (8)	0.0189 (4)
H7	−0.0057	0.1192	0.2802	0.023*
C8	0.2448 (3)	0.1991 (6)	0.17857 (8)	0.0186 (4)
C9	0.4150 (3)	0.2573 (6)	0.13567 (8)	0.0223 (5)
H9	0.5540	0.3651	0.1483	0.027*
C10	0.3819 (4)	0.1584 (6)	0.07468 (9)	0.0258 (5)
H10	0.4987	0.1992	0.0459	0.031*
C11	0.1813 (4)	0.0015 (6)	0.05544 (8)	0.0242 (5)
H11	0.1596	−0.0651	0.0136	0.029*
C12	0.0115 (3)	−0.0580 (6)	0.09787 (8)	0.0248 (5)
H12	−0.1273	−0.1651	0.0849	0.030*
C13	0.0429 (3)	0.0377 (6)	0.15879 (8)	0.0220 (5)
H13	−0.0738	−0.0068	0.1875	0.026*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.0165 (7)	0.0229 (8)	0.0210 (6)	−0.0045 (6)	0.0017 (5)	0.0005 (7)
O2	0.0190 (7)	0.0308 (9)	0.0321 (8)	−0.0093 (7)	−0.0014 (5)	0.0000 (7)
N1	0.0163 (8)	0.0198 (10)	0.0183 (8)	−0.0017 (7)	0.0007 (6)	0.0014 (7)
C1	0.0206 (10)	0.0251 (12)	0.0202 (9)	0.0008 (9)	0.0047 (7)	0.0043 (9)
C2	0.0263 (10)	0.0249 (12)	0.0185 (9)	0.0048 (10)	0.0025 (7)	0.0021 (9)
C3	0.0233 (10)	0.0222 (12)	0.0234 (9)	0.0015 (9)	−0.0033 (7)	−0.0017 (9)
C4	0.0161 (9)	0.0173 (12)	0.0224 (9)	0.0000 (8)	−0.0019 (7)	0.0001 (9)
C5	0.0183 (10)	0.0170 (11)	0.0240 (9)	0.0002 (9)	−0.0017 (7)	0.0007 (9)
C6	0.0146 (9)	0.0166 (11)	0.0220 (9)	−0.0019 (8)	−0.0010 (7)	0.0017 (8)
C7	0.0172 (9)	0.0207 (11)	0.0187 (8)	−0.0025 (8)	−0.0012 (7)	0.0002 (9)
C8	0.0193 (9)	0.0168 (11)	0.0197 (9)	0.0027 (8)	0.0009 (7)	0.0020 (8)
C9	0.0202 (10)	0.0237 (12)	0.0229 (9)	0.0017 (9)	0.0011 (7)	0.0015 (10)
C10	0.0289 (11)	0.0275 (13)	0.0211 (9)	0.0049 (10)	0.0064 (8)	0.0034 (9)
C11	0.0310 (11)	0.0237 (12)	0.0178 (9)	0.0066 (9)	−0.0020 (7)	−0.0001 (9)
C12	0.0239 (10)	0.0248 (12)	0.0255 (10)	0.0016 (10)	−0.0042 (7)	−0.0020 (10)
C13	0.0199 (10)	0.0243 (13)	0.0219 (9)	0.0000 (9)	0.0030 (7)	0.0003 (10)

Geometric parameters (Å, º)

O1—C5	1.380 (2)	C6—C8	1.471 (2)
O1—C6	1.391 (2)	C7—H7	0.9500
O2—C5	1.207 (2)	C8—C9	1.397 (2)
N1—C1	1.363 (2)	C8—C13	1.397 (3)
N1—C4	1.384 (2)	C9—C10	1.389 (3)
N1—C7	1.391 (2)	C9—H9	0.9500
C1—C2	1.377 (3)	C10—C11	1.380 (3)
C1—H1	0.9500	C10—H10	0.9500
C2—C3	1.400 (3)	C11—C12	1.389 (3)
C2—H2	0.9500	C11—H11	0.9500
C3—C4	1.380 (3)	C12—C13	1.383 (3)
C3—H3	0.9500	C12—H12	0.9500
C4—C5	1.438 (2)	C13—H13	0.9500
C6—C7	1.333 (2)
C5—O1—C6	121.88 (14)	C6—C7—N1	119.21 (18)
C1—N1—C4	108.95 (15)	C6—C7—H7	120.4
C1—N1—C7	129.57 (17)	N1—C7—H7	120.4
C4—N1—C7	121.48 (15)	C9—C8—C13	118.58 (17)
N1—C1—C2	107.74 (17)	C9—C8—C6	120.77 (17)
N1—C1—H1	126.1	C13—C8—C6	120.65 (16)
C2—C1—H1	126.1	C10—C9—C8	120.26 (19)
C1—C2—C3	108.45 (17)	C10—C9—H9	119.9
C1—C2—H2	125.8	C8—C9—H9	119.9
C3—C2—H2	125.8	C11—C10—C9	120.78 (17)
C4—C3—C2	106.83 (18)	C11—C10—H10	119.6
C4—C3—H3	126.6	C9—C10—H10	119.6
C2—C3—H3	126.6	C10—C11—C12	119.29 (18)
C3—C4—N1	108.03 (16)	C10—C11—H11	120.4
C3—C4—C5	132.71 (19)	C12—C11—H11	120.4
N1—C4—C5	119.21 (16)	C13—C12—C11	120.47 (19)
O2—C5—O1	117.52 (16)	C13—C12—H12	119.8
O2—C5—C4	125.73 (18)	C11—C12—H12	119.8
O1—C5—C4	116.75 (16)	C12—C13—C8	120.62 (17)
C7—C6—O1	121.35 (17)	C12—C13—H13	119.7
C7—C6—C8	125.48 (18)	C8—C13—H13	119.7
O1—C6—C8	113.17 (15)
C4—N1—C1—C2	−0.7 (2)	C5—O1—C6—C8	179.70 (17)
C7—N1—C1—C2	178.7 (2)	O1—C6—C7—N1	−1.1 (3)
N1—C1—C2—C3	0.9 (2)	C8—C6—C7—N1	179.16 (18)
C1—C2—C3—C4	−0.7 (2)	C1—N1—C7—C6	−179.8 (2)
C2—C3—C4—N1	0.3 (2)	C4—N1—C7—C6	−0.5 (3)
C2—C3—C4—C5	177.6 (2)	C7—C6—C8—C9	−175.2 (2)
C1—N1—C4—C3	0.2 (2)	O1—C6—C8—C9	5.0 (3)
C7—N1—C4—C3	−179.20 (19)	C7—C6—C8—C13	4.5 (3)
C1—N1—C4—C5	−177.49 (18)	O1—C6—C8—C13	−175.29 (19)
C7—N1—C4—C5	3.1 (3)	C13—C8—C9—C10	0.5 (3)
C6—O1—C5—O2	−177.16 (18)	C6—C8—C9—C10	−179.8 (2)
C6—O1—C5—C4	2.6 (3)	C8—C9—C10—C11	0.0 (3)
C3—C4—C5—O2	−1.3 (4)	C9—C10—C11—C12	−0.1 (4)
N1—C4—C5—O2	175.7 (2)	C10—C11—C12—C13	−0.2 (4)
C3—C4—C5—O1	178.9 (2)	C11—C12—C13—C8	0.7 (4)
N1—C4—C5—O1	−4.0 (3)	C9—C8—C13—C12	−0.8 (3)
C5—O1—C6—C7	−0.1 (3)	C6—C8—C13—C12	179.4 (2)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
C7—H7···O2^i	0.95	2.27	3.109 (2)	147

Symmetry code: (i) x−1, y−1, z.