8-Meth­oxy-3-methyl-3,4-di­hydro-2H-1,3-benzoxazine

The title compound, C₁₀H₁₃NO₂, crystallizes with two crystallographically independent mol­ecules of similar geometry in the asymmetric unit; the six-membered oxazine rings adopts a half-chair conformation. Neither hydrogen bonds nor π–π inter­actions are observed in the crystal structure.

Key indicators

• Single-crystal X-ray study
• T = 291 K
• Mean [sigma](C-C) = 0.003 Å
• R factor = 0.041
• wR factor = 0.114
• Data-to-parameter ratio = 13.7

checkCIF/PLATON results

No syntax errors found



Alert level C
PLAT906_ALERT_3_C Large K value in the Analysis of Variance ......      8.918 Check
PLAT911_ALERT_3_C Missing # FCF Refl Between THmin & STh/L=  0.597         13

Alert level G
PLAT005_ALERT_5_G No _iucr_refine_instructions_details  in the CIF     Please Do !
PLAT720_ALERT_4_G Number of Unusual/Non-Standard Labels ..........          7
PLAT909_ALERT_3_G Percentage of Observed Data at Theta(Max) still          60 %
PLAT910_ALERT_3_G Missing # of FCF Reflections Below Th(Min) .....          1 Why ?

   0 ALERT level A = Most likely a serious problem - resolve or explain
   0 ALERT level B = A potentially serious problem, consider carefully
   2 ALERT level C = Check. Ensure it is not caused by an omission or oversight
   4 ALERT level G = General information/check it is not something unexpected

   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
   4 ALERT type 3 Indicator that the structure quality may be low
   1 ALERT type 4 Improvement, methodology, query or suggestion
   1 ALERT type 5 Informative message, check

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S1. Comment

Benzo[e][1,3]oxazines, which are synthesized by an amine, a phenolic compound and formaldehyde via Mannich reaction (Holly & Cope, 1944), are a useful class of heterocyclic compounds. They can be cured via thermal ring-opening polymerization to construct a novel class of thermosetting resins called polybenzoxazins (Ning & Ishida, 1994). Polybenzoxazines have been widely used as automobile braking materials (Gu et al., 1998), copper clad laminates (Zheng et al., 2011), electronic packaging materials (Rimdusit & Ishida, 2000), aircraft cabin sidewalls (Stewart, 2009). The title compound was prepared by reaction of 2-methoxyphenol, formaldehyde and methylamine and its crystal structure is described herein.

The asymmetric unit of the title compound consists of two crystallographically independent molecules of similar geometry (Fig. 1). In both molecules the six-membered oxazine rings adopt a half-chair conformation, with atoms N1, C1 and N1', C1' displaced on opposite sides of the C2-C4/O1 (r.m.s deviation 0.0017 Å) and C2'-C4'/O1' (r.m.s deviation 0.0024 Å) mean planes by 0.4941 (15), 0.2019 (17) Å and 0.3664 (16), 0.351 (2) Å, respectively. The puckering parameters (Cremer & Pople, 1975) are Q = 0.4664 (16) Å, θ = 129.48 (19)°, ϕ = -75.7 (2)° for ring O1/C1/N1/C2–C4, and Q = 0.4722 (17) Å, θ = 128.97 (18)°, ϕ = -89.0 (3)° for ring O1'/C1'/N1'/C2'–C4'. In the crystal structure, no hydrogen bonding or π–π stacking interactions are observed.

Related literature

For the synthesis and applications of 1,3-benzoxazines, see: Holly & Cope (1944); Gu et al. (1998); Zheng et al. (2011); Rimdusit & Ishida (2000); Stewart (2009); Ning & Ishida (1994). For puckering parameters, see: Cremer & Pople (1975).

S2. Experimental

Methylamine (40 wt% in water; 3.9 g, 0.05 mol), formaldehyde (37% wt in water; 8.1 g, 0.1 mol), 4-methoxyphenol (6.2 g, 0.05 mol) and 1, 4-dioxine (50 ml) were added to a 250 ml flask equipped with a condenser. The mixture was stirred at 90 °C for 5 h. After condensed by rotary evaporator, a yellowish-brown viscous liquid was obtained and set at room temperature for a few hours. After washing several times with methanol, a yellowish powder was precipitated. Anhydrous ether was used to dissolve the powder, and colourless crystals suitable for X-ray diffraction analysis were obtained by slow evoporation of the solvent.

S3. Refinement

All H atoms were refined using a riding model approximation, with C—H = 0.93–0.97 Å and with U_iso(H) = 1.2 U_eq(C) or 1.5 U_eq(C) for methyl H atoms.

Computing details

Data collection: CrysAlis PRO (Agilent, 2012); cell refinement: CrysAlis PRO (Agilent, 2012); data reduction: CrysAlis PRO (Agilent, 2012); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: OLEX2 (Dolomanov et al., 2009); software used to prepare material for publication: OLEX2 (Dolomanov et al., 2009).

Figures

Fig. 1. The asymmetric unit of the title complound with displacement ellipsoids drawn at the 50% probability level.

8-Methoxy-3-methyl-3,4-dihydro-2H-1,3-benzoxazine

Crystal data

C10H13NO2	F(000) = 768
Mr = 179.21	Dx = 1.284 Mg m^−3
Monoclinic, P21/c	Cu Kα radiation, λ = 1.5418 Å
Hall symbol: -P 2ybc	Cell parameters from 2369 reflections
a = 23.4234 (14) Å	θ = 3.2–66.9°
b = 5.0054 (3) Å	µ = 0.73 mm^−1
c = 15.9408 (10) Å	T = 291 K
β = 97.210 (6)°	Prism, colourless
V = 1854.2 (2) Å^3	0.22 × 0.20 × 0.18 mm
Z = 8

Data collection

Agilent Xcalibur (Eos, Gemini) diffractometer	3281 independent reflections
Radiation source: Enhance (Cu) X-ray Source	2471 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.030
Detector resolution: 16.2312 pixels mm^-1	θmax = 67.1°, θmin = 3.8°
ω scans	h = −19→27
Absorption correction: multi-scan (CrysAlis PRO; Agilent, 2012)	k = −3→5
Tmin = 0.783, Tmax = 1.000	l = −18→19
6857 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)] = 0.041	H-atom parameters constrained
wR(F^2) = 0.114	w = 1/[σ^2(Fo^2) + (0.0524P)^2] where P = (Fo^2 + 2Fc^2)/3
S = 1.02	(Δ/σ)max < 0.001
3281 reflections	Δρmax = 0.15 e Å^−3
240 parameters	Δρmin = −0.16 e Å^−3
0 restraints	Extinction correction: SHELXL97 (Sheldrick, 2008), Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.0041 (3)

Special details

Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s 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	0.93754 (5)	0.7027 (2)	0.81029 (8)	0.0481 (3)
O2	0.93639 (5)	1.0466 (3)	0.93130 (8)	0.0507 (3)
N1	0.89328 (8)	0.5131 (3)	0.67831 (9)	0.0538 (4)
C1	0.93598 (8)	0.4853 (3)	0.74936 (12)	0.0526 (4)
H1A	0.9734	0.4725	0.7294	0.063*
H1B	0.9293	0.3192	0.7779	0.063*
C2	0.83649 (9)	0.5122 (4)	0.70753 (12)	0.0549 (5)
H2A	0.8282	0.3343	0.7268	0.066*
H2B	0.8075	0.5574	0.6607	0.066*
C3	0.83340 (7)	0.7092 (3)	0.77871 (10)	0.0429 (4)
C4	0.88444 (7)	0.7904 (3)	0.82559 (10)	0.0384 (3)
C5	0.88378 (7)	0.9799 (3)	0.89037 (9)	0.0395 (3)
C6	0.83181 (8)	1.0838 (4)	0.90755 (11)	0.0498 (4)
H6	0.8309	1.2096	0.9503	0.060*
C7	0.78089 (8)	1.0000 (4)	0.86090 (12)	0.0566 (5)
H7	0.7460	1.0694	0.8729	0.068*
C8	0.78165 (8)	0.8159 (4)	0.79739 (12)	0.0540 (5)
H8	0.7472	0.7620	0.7665	0.065*
C9	0.90299 (11)	0.7484 (4)	0.62759 (12)	0.0672 (6)
H9A	0.8977	0.9070	0.6595	0.101*
H9B	0.8761	0.7481	0.5769	0.101*
H9C	0.9415	0.7445	0.6131	0.101*
C10	0.93882 (9)	1.2585 (4)	0.99146 (12)	0.0551 (5)
H10D	0.9778	1.2823	1.0170	0.083*
H10E	0.9150	1.2153	1.0343	0.083*
H10F	0.9253	1.4206	0.9635	0.083*
O1'	0.33443 (5)	0.5282 (3)	0.32961 (8)	0.0572 (4)
O2'	0.28466 (6)	0.1922 (3)	0.42062 (9)	0.0659 (4)
N1'	0.41648 (7)	0.7858 (3)	0.30046 (10)	0.0520 (4)
C1'	0.35547 (8)	0.7584 (4)	0.28753 (13)	0.0590 (5)
H1'A	0.3430	0.7444	0.2273	0.071*
H1'B	0.3383	0.9184	0.3078	0.071*
C2'	0.43450 (8)	0.8338 (4)	0.39037 (12)	0.0521 (4)
H2'A	0.4257	1.0171	0.4037	0.063*
H2'B	0.4759	0.8107	0.4020	0.063*
C3'	0.40554 (7)	0.6489 (3)	0.44663 (11)	0.0435 (4)
C4'	0.35742 (7)	0.5065 (3)	0.41245 (10)	0.0426 (4)
C5'	0.33050 (7)	0.3264 (4)	0.46242 (11)	0.0467 (4)
C6'	0.35111 (8)	0.2984 (4)	0.54686 (12)	0.0547 (5)
H6'	0.3334	0.1806	0.5806	0.066*
C7'	0.39836 (9)	0.4464 (4)	0.58138 (12)	0.0622 (5)
H7'	0.4118	0.4299	0.6386	0.075*
C8'	0.42559 (8)	0.6174 (4)	0.53176 (12)	0.0566 (5)
H8'	0.4577	0.7129	0.5555	0.068*
C9'	0.44587 (9)	0.5579 (4)	0.26797 (13)	0.0611 (5)
H9'A	0.4335	0.5381	0.2086	0.092*
H9'B	0.4367	0.3986	0.2971	0.092*
H9'C	0.4867	0.5870	0.2769	0.092*
C10'	0.25623 (10)	0.0001 (5)	0.46693 (16)	0.0750 (7)
H10A	0.2276	−0.0919	0.4292	0.113*
H10B	0.2381	0.0892	0.5099	0.113*
H10C	0.2839	−0.1262	0.4929	0.113*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.0447 (6)	0.0478 (7)	0.0533 (7)	0.0041 (5)	0.0126 (5)	−0.0065 (5)
O2	0.0476 (6)	0.0544 (8)	0.0491 (7)	−0.0022 (5)	0.0019 (5)	−0.0106 (5)
N1	0.0802 (11)	0.0369 (8)	0.0467 (8)	−0.0029 (7)	0.0177 (7)	−0.0041 (6)
C1	0.0652 (11)	0.0365 (9)	0.0600 (11)	0.0048 (8)	0.0233 (9)	−0.0010 (8)
C2	0.0696 (11)	0.0432 (10)	0.0512 (10)	−0.0098 (9)	0.0047 (8)	−0.0056 (8)
C3	0.0495 (9)	0.0367 (9)	0.0425 (8)	−0.0048 (7)	0.0052 (7)	0.0024 (7)
C4	0.0429 (8)	0.0342 (8)	0.0395 (8)	0.0005 (6)	0.0107 (6)	0.0052 (6)
C5	0.0440 (8)	0.0382 (8)	0.0367 (8)	−0.0009 (6)	0.0070 (6)	0.0029 (6)
C6	0.0524 (9)	0.0531 (11)	0.0462 (9)	0.0048 (8)	0.0149 (7)	−0.0062 (8)
C7	0.0420 (9)	0.0655 (13)	0.0641 (11)	0.0074 (8)	0.0137 (8)	−0.0021 (9)
C8	0.0421 (9)	0.0594 (12)	0.0592 (11)	−0.0060 (8)	0.0018 (7)	0.0027 (9)
C9	0.1094 (18)	0.0485 (11)	0.0476 (10)	−0.0042 (11)	0.0247 (11)	0.0001 (8)
C10	0.0690 (12)	0.0457 (10)	0.0487 (10)	−0.0082 (9)	0.0007 (8)	−0.0047 (8)
O1'	0.0515 (7)	0.0706 (9)	0.0478 (7)	−0.0120 (6)	−0.0001 (5)	0.0058 (6)
O2'	0.0581 (8)	0.0701 (10)	0.0703 (9)	−0.0205 (7)	0.0115 (7)	0.0027 (7)
N1'	0.0555 (9)	0.0455 (9)	0.0569 (9)	0.0002 (7)	0.0140 (7)	0.0066 (7)
C1'	0.0571 (11)	0.0656 (13)	0.0535 (10)	0.0049 (9)	0.0038 (8)	0.0141 (9)
C2'	0.0529 (10)	0.0394 (10)	0.0649 (11)	−0.0051 (8)	0.0106 (8)	−0.0029 (8)
C3'	0.0427 (8)	0.0380 (9)	0.0500 (9)	0.0045 (7)	0.0067 (7)	−0.0041 (7)
C4'	0.0410 (8)	0.0437 (9)	0.0435 (8)	0.0047 (7)	0.0065 (6)	0.0002 (7)
C5'	0.0431 (8)	0.0435 (9)	0.0552 (9)	0.0022 (7)	0.0129 (7)	0.0000 (8)
C6'	0.0588 (10)	0.0534 (11)	0.0543 (10)	0.0077 (8)	0.0162 (8)	0.0108 (8)
C7'	0.0679 (12)	0.0727 (14)	0.0452 (10)	0.0100 (10)	0.0034 (8)	0.0042 (9)
C8'	0.0542 (10)	0.0595 (12)	0.0539 (10)	−0.0021 (9)	−0.0019 (8)	−0.0070 (9)
C9'	0.0687 (12)	0.0534 (11)	0.0647 (12)	−0.0026 (10)	0.0224 (9)	−0.0002 (9)
C10'	0.0768 (14)	0.0602 (14)	0.0950 (17)	−0.0200 (11)	0.0375 (13)	−0.0054 (12)

Geometric parameters (Å, º)

O1—C1	1.456 (2)	O1'—C1'	1.451 (2)
O1—C4	1.3695 (19)	O1'—C4'	1.366 (2)
O2—C5	1.362 (2)	O2'—C5'	1.367 (2)
O2—C10	1.426 (2)	O2'—C10'	1.427 (2)
N1—C1	1.421 (3)	N1'—C1'	1.425 (2)
N1—C2	1.464 (2)	N1'—C2'	1.462 (2)
N1—C9	1.463 (2)	N1'—C9'	1.461 (2)
C1—H1A	0.9700	C1'—H1'A	0.9700
C1—H1B	0.9700	C1'—H1'B	0.9700
C2—H2A	0.9700	C2'—H2'A	0.9700
C2—H2B	0.9700	C2'—H2'B	0.9700
C2—C3	1.512 (2)	C2'—C3'	1.508 (2)
C3—C4	1.389 (2)	C3'—C4'	1.386 (2)
C3—C8	1.391 (2)	C3'—C8'	1.388 (3)
C4—C5	1.404 (2)	C4'—C5'	1.404 (2)
C5—C6	1.382 (2)	C5'—C6'	1.379 (3)
C6—H6	0.9300	C6'—H6'	0.9300
C6—C7	1.389 (3)	C6'—C7'	1.387 (3)
C7—H7	0.9300	C7'—H7'	0.9300
C7—C8	1.370 (3)	C7'—C8'	1.375 (3)
C8—H8	0.9300	C8'—H8'	0.9300
C9—H9A	0.9600	C9'—H9'A	0.9600
C9—H9B	0.9600	C9'—H9'B	0.9600
C9—H9C	0.9600	C9'—H9'C	0.9600
C10—H10D	0.9600	C10'—H10A	0.9600
C10—H10E	0.9600	C10'—H10B	0.9600
C10—H10F	0.9600	C10'—H10C	0.9600
C4—O1—C1	114.28 (13)	C4'—O1'—C1'	113.24 (14)
C5—O2—C10	117.51 (14)	C5'—O2'—C10'	117.90 (17)
C1—N1—C2	108.85 (14)	C1'—N1'—C2'	108.58 (15)
C1—N1—C9	112.13 (16)	C1'—N1'—C9'	112.47 (16)
C9—N1—C2	112.88 (17)	C9'—N1'—C2'	112.64 (15)
O1—C1—H1A	108.6	O1'—C1'—H1'A	108.8
O1—C1—H1B	108.6	O1'—C1'—H1'B	108.8
N1—C1—O1	114.52 (14)	N1'—C1'—O1'	113.74 (15)
N1—C1—H1A	108.6	N1'—C1'—H1'A	108.8
N1—C1—H1B	108.6	N1'—C1'—H1'B	108.8
H1A—C1—H1B	107.6	H1'A—C1'—H1'B	107.7
N1—C2—H2A	109.3	N1'—C2'—H2'A	109.0
N1—C2—H2B	109.3	N1'—C2'—H2'B	109.0
N1—C2—C3	111.61 (15)	N1'—C2'—C3'	112.71 (14)
H2A—C2—H2B	108.0	H2'A—C2'—H2'B	107.8
C3—C2—H2A	109.3	C3'—C2'—H2'A	109.0
C3—C2—H2B	109.3	C3'—C2'—H2'B	109.0
C4—C3—C2	118.41 (16)	C4'—C3'—C2'	119.09 (15)
C4—C3—C8	119.13 (16)	C4'—C3'—C8'	118.99 (17)
C8—C3—C2	122.45 (16)	C8'—C3'—C2'	121.92 (16)
O1—C4—C3	123.36 (15)	O1'—C4'—C3'	122.78 (16)
O1—C4—C5	116.23 (14)	O1'—C4'—C5'	116.67 (15)
C3—C4—C5	120.36 (15)	C3'—C4'—C5'	120.54 (16)
O2—C5—C4	115.17 (14)	O2'—C5'—C4'	114.85 (16)
O2—C5—C6	125.41 (15)	O2'—C5'—C6'	125.68 (17)
C6—C5—C4	119.42 (15)	C6'—C5'—C4'	119.48 (17)
C5—C6—H6	120.0	C5'—C6'—H6'	120.1
C5—C6—C7	119.92 (16)	C5'—C6'—C7'	119.81 (18)
C7—C6—H6	120.0	C7'—C6'—H6'	120.1
C6—C7—H7	119.7	C6'—C7'—H7'	119.7
C8—C7—C6	120.57 (17)	C8'—C7'—C6'	120.59 (18)
C8—C7—H7	119.7	C8'—C7'—H7'	119.7
C3—C8—H8	119.7	C3'—C8'—H8'	119.7
C7—C8—C3	120.59 (16)	C7'—C8'—C3'	120.55 (18)
C7—C8—H8	119.7	C7'—C8'—H8'	119.7
N1—C9—H9A	109.5	N1'—C9'—H9'A	109.5
N1—C9—H9B	109.5	N1'—C9'—H9'B	109.5
N1—C9—H9C	109.5	N1'—C9'—H9'C	109.5
H9A—C9—H9B	109.5	H9'A—C9'—H9'B	109.5
H9A—C9—H9C	109.5	H9'A—C9'—H9'C	109.5
H9B—C9—H9C	109.5	H9'B—C9'—H9'C	109.5
O2—C10—H10D	109.5	O2'—C10'—H10A	109.5
O2—C10—H10E	109.5	O2'—C10'—H10B	109.5
O2—C10—H10F	109.5	O2'—C10'—H10C	109.5
H10D—C10—H10E	109.5	H10A—C10'—H10B	109.5
H10D—C10—H10F	109.5	H10A—C10'—H10C	109.5
H10E—C10—H10F	109.5	H10B—C10'—H10C	109.5
O1—C4—C5—O2	−1.7 (2)	O1'—C4'—C5'—O2'	0.8 (2)
O1—C4—C5—C6	177.98 (15)	O1'—C4'—C5'—C6'	−179.01 (16)
O2—C5—C6—C7	179.74 (17)	O2'—C5'—C6'—C7'	179.68 (18)
N1—C2—C3—C4	−21.6 (2)	N1'—C2'—C3'—C4'	−15.2 (2)
N1—C2—C3—C8	156.76 (17)	N1'—C2'—C3'—C8'	164.96 (17)
C1—O1—C4—C3	−9.1 (2)	C1'—O1'—C4'—C3'	−14.7 (2)
C1—O1—C4—C5	173.47 (14)	C1'—O1'—C4'—C5'	166.48 (16)
C1—N1—C2—C3	50.6 (2)	C1'—N1'—C2'—C3'	45.4 (2)
C2—N1—C1—O1	−62.57 (19)	C2'—N1'—C1'—O1'	−64.2 (2)
C2—C3—C4—O1	0.5 (2)	C2'—C3'—C4'—O1'	−0.7 (2)
C2—C3—C4—C5	177.80 (15)	C2'—C3'—C4'—C5'	178.01 (16)
C2—C3—C8—C7	−178.06 (18)	C2'—C3'—C8'—C7'	−179.74 (18)
C3—C4—C5—O2	−179.24 (14)	C3'—C4'—C5'—O2'	−177.96 (15)
C3—C4—C5—C6	0.5 (2)	C3'—C4'—C5'—C6'	2.2 (3)
C4—O1—C1—N1	41.2 (2)	C4'—O1'—C1'—N1'	48.5 (2)
C4—C3—C8—C7	0.3 (3)	C4'—C3'—C8'—C7'	0.4 (3)
C4—C5—C6—C7	0.1 (3)	C4'—C5'—C6'—C7'	−0.5 (3)
C5—C6—C7—C8	−0.4 (3)	C5'—C6'—C7'—C8'	−1.2 (3)
C6—C7—C8—C3	0.2 (3)	C6'—C7'—C8'—C3'	1.3 (3)
C8—C3—C4—O1	−178.00 (15)	C8'—C3'—C4'—O1'	179.13 (16)
C8—C3—C4—C5	−0.7 (2)	C8'—C3'—C4'—C5'	−2.1 (3)
C9—N1—C1—O1	63.0 (2)	C9'—N1'—C1'—O1'	61.2 (2)
C9—N1—C2—C3	−74.6 (2)	C9'—N1'—C2'—C3'	−79.85 (19)
C10—O2—C5—C4	173.49 (14)	C10'—O2'—C5'—C4'	178.22 (17)
C10—O2—C5—C6	−6.2 (2)	C10'—O2'—C5'—C6'	−1.9 (3)