Crystal structure of methyl 1-allyl-4-methyl-1H-benzo[c][1,2]thia-zine-3-carboxyl-ate 2,2-dioxide.

In the title compound, C14H15NO4S, the di-hydro-thia-zine ring adopts a distorted sofa conformation with the S atom displaced from the mean plane through the N and C ring atoms by 0.767 (1) Å. The allyl substituent (C-C=C) is inclined to this mean plane by 78.5 (7)° and the acetate group [C(=O)-O-C] by 66.5 (3)°. In the crystal, mol-ecules are linked by C-H⋯π inter-actions forming chains propagating along the a-axis direction.

Chemical context

Alkyl­ation of nitro­gen heterocycles, particularly those containing reactive exocyclic groups, always attracts attention with its ambiguity and dependence on a variety of factors. For example, esters of 4-hy­droxy-2-oxo-1,2-di­hydro­quinoline-3-carb­oxy­lic acids are primarily alkyl­ated exclusively at the 4-OH group (Ukrainets et al., 1996 ▸). However, methyl 4-hy­droxy-2,2-dioxo-1H-2λ6,1-benzo­thia­zine-3-carboxyl­ates that are structurally close to them easily form mixtures of isomeric 3-C- and 4-O-alkyl­ation products under the same conditions (Ukrainets et al., 2015 ▸). Consequently, it is quite difficult to predict their behaviour in the alkyl­ation reactions of the esters of 4-methyl-2,2-dioxo-1H-2λ6,1-benzo­thia­zine-3-carb­oxy­lic acids, and the determination of the true structure is essential. It has been found that methyl 4-methyl-2,2-dioxo-1H-2λ6,1-benzo­thia­zine-3-carboxyl­ate 1 in the K2CO3/DMSO system is rapidly alkyl­ated with allyl bromide 2 by the cyclic nitro­gen atom, with formation of the main product of the reaction studied viz. compound 3 (see Fig. 1 ▸).

Figure 1

The synthesis of the title compound, 3.

Structural commentary

The mol­ecular structure of the title compound, 3, is illustrated in Fig. 2 ▸. The di­hydro­thia­zine ring adopts a distorted sofa conformation: the puckering parameters (Zefirov et al., 1990 ▸) are: S = 0.67, Θ = 57.1°, Ψ = 19.0°. Atom S1 deviates from the mean plane of the remaining atoms (N1/C1/C6–C8) by 0.767 (1) Å. The allyl substituent (C—C=C) is inclined to this mean plane by 78.5 (7)° and the acetate group (O=C—O—C) by 66.5 (3)°. Atom N1 has a planar configuration, the sum of the bond angles being 359.1°.

Figure 2

The mol­ecular structure of compound 3, with atom labelling. Displacement ellipsoids are drawn at the 50% probability level.

The strong steric repulsion between methyl group at the C7 atom and the aromatic ring {there are short intra­molecular contacts H5⋯C11 = 2.63 and H11A⋯C5 = 2.47 Å in this fragment [the sum of the van der Waals radii (Zefirov, 1997 ▸) is 2.87 Å]} causes a disturbance of the conjugation between the π-systems of the aromatic ring and the C7=C8 double bond; the C5—C6—C7—C8 torsion angle is −164.7 (4)°. The ester substituent is twisted relatively to the C7=C8 endocyclic double bond [the C7—C8—C9—O1 torsion angle is 46.0 (7)°], leading to its elongation: the C7=C8 bond length is 1.348 (6) Å as compared to the mean value of 1.326 Å (Bürgi & Dunitz, 1994 ▸). The methyl group of the ester substituent is located in the ap-position to the C8—C9 bond [C8—C9—O2—C10 = −171.5 (5)°]. The allyl group is orthogonal to the benzo­thia­zine fragment plane while the terminal double bond is synperiplanar to the N1—C12 bond [torsion angles C1—N1—C12—C13 and N1—C12—C13—C14 are 97.2 (5) and 3.5 (8)°, respectively]. The steric repulsion between the allyl substituent and the aromatic cycle (short intra­molecular contacts H2⋯C12 = 2.77 Å and H12A⋯C2 = 2.83 Å) results in the elongation of the C1—N1 bond [1.411 (5) Å], compared with the mean value of 1.371 Å (Bürgi & Dunitz, 1994 ▸).

Supra­molecular features

In the crystal, mol­ecules are linked by C—H⋯π inter­actions, forming chains propagating along the a-axis direction. (Table 1 ▸ and Fig. 3 ▸). There are no other significant inter­molecular inter­actions in the crystal structure, despite the presence of a number of potential donor and acceptor atoms.

Table 1

Hydrogen-bond geometry (Å, °)

Cg is the centroid of the C1–C6 ring.

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C12—H12A⋯Cg i	0.97	2.95	3.576 (5)	123

Symmetry code: (i) .

Figure 3

A view along the c axis of the crystal packing of compound 3. The C—H⋯π inter­actions are represented by dashed lines (see Table 1 ▸) and, for clarity, only H atom H12A (grey ball) is included.

Database survey

A search of the Cambridge Structural Database (Version 5.37, update May 2016; Groom et al., 2016 ▸) for 1H-benzo[c][1,2]thia­zine 2,2-dioxide yielded 15 hits. These include the 4-hy­droxy analogue of the title compound, viz. methyl 1-allyl-4-hy­droxy-1H-benzo[c][1,2]thia­zine-3-carboxyl­ate 2,2-dioxide (MINJAW; Shishkina et al., 2013 ▸). This compound crystallized with two mol­ecules in the asymmetric unit. The conformation of the di­hydro­thia­zine ring in both mol­ecules resembles that in the title compound, which has a distorted sofa conformation. A view of the structural overlap of the three mol­ecules is shown in Fig. 4 ▸.

Figure 4

The structural overlap of the two independent mol­ecules of the 4-hy­droxy analogue (MINJAW; Shishkina et al., 2013 ▸), and the title compound 3, shown in blue.

Synthesis and crystallization

The synthesis of the title compound, 3, is illustrated in Fig. 1 ▸. To a solution of 2.53 g (0.01 mol) of methyl 4-methyl-2,2-dioxo-1H-2λ6,1-benzo­thia­zine-3-carboxyl­ate, 1, in 20 ml DMSO were added 2.07 g (0.015 mol) of K2CO3 and the mixture was stirred for 30 min. Allyl bromide (1.81 g, 0.015 mol) was then added and the mixture was stirred for a further 30 min at 298 K. It was then diluted with cold water and acidified with dilute HCl to pH 4. It was extracted with CH2Cl2 (3 × 10 ml). The organic extracts were combined and the solvent removed by distillation (at reduced pressure at the end). The residue was dissolved in 20 ml of hot methanol and filtered over charcoal. The resulting solution was then placed in a freezer (253 K) for 24 h, after which crystals of the title compound were harvested (yield 2.55 g, 87%; m.p. 360–362 K).

Refinement

Crystal data, data collection and structure refinement details are summarized in Table 2 ▸. H atoms could all be located in difference Fourier maps. During refinement they were included in calculated positions and treated as riding: C—H = 0.93–0.97 Å with U iso = 1.5U eq(C-meth­yl) and 1.2U eq(C) for other H atoms.

Table 2

Experimental details

Crystal data
Chemical formula	C14H15NO4S
M r	293.33
Crystal system, space group	Orthorhombic, P n a21
Temperature (K)	293
a, b, c (Å)	10.1970 (7), 18.6174 (12), 7.5136 (5)
V (Å3)	1426.39 (16)
Z	4
Radiation type	Mo Kα
μ (mm−1)	0.24
Crystal size (mm)	0.20 × 0.10 × 0.02
Data collection
Diffractometer	Agilent Xcalibur Sapphire3
Absorption correction	Multi-scan (CrysAlis RED; Agilent, 2012 ▸)
T min, T max	0.706, 1.000
No. of measured, independent and observed [I > 2σ(I)] reflections	9346, 2425, 2111
R int	0.056
(sin θ/λ)max (Å−1)	0.595
Refinement
R[F 2 > 2σ(F 2)], wR(F 2), S	0.044, 0.120, 1.05
No. of reflections	2425
No. of parameters	181
No. of restraints	1
H-atom treatment	H-atom parameters constrained
Δρmax, Δρmin (e Å−3)	0.19, −0.20
Absolute structure	Flack x determined using 785 quotients [(I +)−(I −)]/[(I +)+(I −)] (Parsons et al., 2013 ▸)
Absolute structure parameter	0.09 (8)

Computer programs: CrysAlis CCD and CrysAlis RED (Agilent, 2012 ▸), SHELXS2014 (Sheldrick, 2008 ▸), SHELXTL (Sheldrick, 2008 ▸), Mercury (Macrae et al., 2008 ▸), SHELXL2014 (Sheldrick, 2015 ▸), PLATON (Spek, 2009 ▸) and publCIF (Westrip, 2010 ▸).

Crystal structure: contains datablock(s) I, Global. DOI: 10.1107/S2056989016015978/su5329sup1.cif

Structure factors: contains datablock(s) I. DOI: 10.1107/S2056989016015978/su5329Isup2.hkl

Click here for additional data file.

Supporting information file. DOI: 10.1107/S2056989016015978/su5329Isup3.cml

CCDC reference: 1508990

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

C14H15NO4S	Dx = 1.366 Mg m−3
Mr = 293.33	Mo Kα radiation, λ = 0.71073 Å
Orthorhombic, Pna21	Cell parameters from 2163 reflections
a = 10.1970 (7) Å	θ = 3.8–25.1°
b = 18.6174 (12) Å	µ = 0.24 mm−1
c = 7.5136 (5) Å	T = 293 K
V = 1426.39 (16) Å3	Plate, colourless
Z = 4	0.20 × 0.10 × 0.02 mm
F(000) = 616

Agilent Xcalibur Sapphire3 diffractometer	2425 independent reflections
Radiation source: Enhance (Mo) X-ray Source	2111 reflections with I > 2σ(I)
Detector resolution: 16.1827 pixels mm-1	Rint = 0.056
ω–scans	θmax = 25.0°, θmin = 3.0°
Absorption correction: multi-scan (CrysAlis RED; Agilent, 2012)	h = −12→10
Tmin = 0.706, Tmax = 1.000	k = −22→22
9346 measured reflections	l = −7→8

Refinement on F2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.044	H-atom parameters constrained
wR(F2) = 0.120	w = 1/[σ2(Fo2) + (0.0618P)2 + 0.1291P] where P = (Fo2 + 2Fc2)/3
S = 1.05	(Δ/σ)max < 0.001
2425 reflections	Δρmax = 0.19 e Å−3
181 parameters	Δρmin = −0.20 e Å−3
1 restraint	Absolute structure: Flack x determined using 785 quotients [(I+)-(I-)]/[(I+)+(I-)] (Parsons et al., 2013)
Primary atom site location: structure-invariant direct methods	Absolute structure parameter: 0.09 (8)

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.

	x	y	z	Uiso*/Ueq
S1	0.88243 (9)	0.65549 (5)	0.26457 (17)	0.0457 (3)
O1	0.6502 (4)	0.5240 (2)	0.4865 (7)	0.0975 (14)
O2	0.7649 (4)	0.51032 (18)	0.2347 (6)	0.0801 (11)
O3	0.7789 (3)	0.66144 (16)	0.1376 (5)	0.0645 (9)
O4	1.0109 (3)	0.63899 (17)	0.2033 (4)	0.0590 (9)
N1	0.8881 (3)	0.73110 (17)	0.3775 (5)	0.0457 (8)
C1	0.9692 (4)	0.7307 (2)	0.5295 (6)	0.0443 (9)
C2	1.0333 (4)	0.7933 (3)	0.5818 (7)	0.0559 (11)
H2	1.0205	0.8355	0.5180	0.067*
C3	1.1146 (4)	0.7932 (3)	0.7260 (7)	0.0652 (14)
H3	1.1557	0.8355	0.7611	0.078*
C4	1.1362 (5)	0.7308 (3)	0.8195 (7)	0.0722 (15)
H4	1.1956	0.7305	0.9135	0.087*
C5	1.0705 (5)	0.6690 (3)	0.7747 (8)	0.0605 (11)
H5	1.0837	0.6277	0.8419	0.073*
C6	0.9842 (4)	0.6670 (2)	0.6302 (6)	0.0461 (10)
C7	0.9017 (4)	0.6034 (2)	0.5943 (6)	0.0490 (10)
C8	0.8424 (4)	0.5951 (2)	0.4353 (6)	0.0497 (11)
C9	0.7425 (5)	0.5388 (2)	0.3921 (8)	0.0623 (13)
C10	0.6651 (7)	0.4617 (4)	0.1624 (12)	0.110 (3)
H10A	0.6927	0.4446	0.0478	0.165*
H10B	0.6537	0.4217	0.2415	0.165*
H10C	0.5835	0.4870	0.1506	0.165*
C11	0.8826 (5)	0.5494 (3)	0.7415 (9)	0.0715 (15)
H11A	0.9319	0.5640	0.8442	0.107*
H11B	0.7913	0.5467	0.7717	0.107*
H11C	0.9126	0.5031	0.7025	0.107*
C12	0.7970 (4)	0.7897 (2)	0.3411 (7)	0.0547 (11)
H12A	0.7753	0.8127	0.4530	0.066*
H12B	0.7168	0.7693	0.2936	0.066*
C13	0.8440 (5)	0.8458 (2)	0.2154 (8)	0.0661 (15)
H13	0.7888	0.8848	0.1961	0.079*
C14	0.9528 (6)	0.8455 (3)	0.1316 (9)	0.0829 (18)
H14A	1.0112	0.8076	0.1466	0.099*
H14B	0.9737	0.8832	0.0555	0.099*

	U11	U22	U33	U12	U13	U23
S1	0.0486 (5)	0.0440 (5)	0.0446 (5)	−0.0024 (4)	−0.0040 (5)	−0.0029 (5)
O1	0.087 (3)	0.089 (3)	0.116 (4)	−0.038 (2)	0.020 (3)	−0.007 (3)
O2	0.084 (2)	0.063 (2)	0.094 (3)	−0.0162 (18)	−0.005 (2)	−0.028 (2)
O3	0.070 (2)	0.062 (2)	0.062 (2)	−0.0037 (16)	−0.0255 (17)	−0.0033 (16)
O4	0.0587 (18)	0.0636 (19)	0.0546 (19)	−0.0032 (15)	0.0108 (14)	−0.0081 (14)
N1	0.0528 (19)	0.0364 (17)	0.048 (2)	−0.0005 (14)	−0.0052 (15)	−0.0030 (17)
C1	0.044 (2)	0.046 (2)	0.043 (2)	−0.0011 (18)	0.0033 (18)	−0.0031 (18)
C2	0.061 (3)	0.053 (3)	0.053 (3)	−0.008 (2)	0.004 (2)	−0.005 (2)
C3	0.070 (3)	0.075 (3)	0.051 (3)	−0.020 (3)	0.005 (2)	−0.015 (2)
C4	0.075 (3)	0.096 (4)	0.046 (3)	−0.009 (3)	−0.013 (2)	−0.008 (3)
C5	0.070 (3)	0.067 (3)	0.045 (2)	0.005 (2)	−0.009 (3)	0.001 (3)
C6	0.049 (2)	0.047 (2)	0.042 (2)	0.0024 (18)	0.0034 (18)	−0.0002 (18)
C7	0.055 (2)	0.042 (2)	0.050 (3)	0.0070 (18)	0.003 (2)	0.0025 (19)
C8	0.051 (2)	0.038 (2)	0.060 (3)	−0.0031 (18)	0.003 (2)	−0.0031 (19)
C9	0.062 (3)	0.046 (2)	0.079 (4)	−0.009 (2)	0.000 (3)	0.000 (2)
C10	0.112 (5)	0.070 (4)	0.149 (7)	−0.028 (4)	−0.040 (5)	−0.028 (4)
C11	0.093 (4)	0.053 (3)	0.068 (4)	−0.001 (2)	−0.002 (3)	0.014 (3)
C12	0.054 (2)	0.046 (2)	0.064 (3)	0.0025 (19)	−0.001 (2)	0.001 (2)
C13	0.067 (3)	0.051 (3)	0.081 (4)	0.003 (2)	0.000 (3)	0.011 (2)
C14	0.076 (4)	0.090 (4)	0.082 (4)	−0.001 (3)	−0.001 (3)	0.026 (3)

S1—O4	1.422 (3)	C5—H5	0.9300
S1—O3	1.427 (3)	C6—C7	1.477 (6)
S1—N1	1.645 (3)	C7—C8	1.348 (6)
S1—C8	1.754 (4)	C7—C11	1.508 (7)
O1—C9	1.210 (6)	C8—C9	1.497 (6)
O2—C9	1.316 (6)	C10—H10A	0.9600
O2—C10	1.466 (6)	C10—H10B	0.9600
N1—C1	1.411 (5)	C10—H10C	0.9600
N1—C12	1.458 (5)	C11—H11A	0.9600
C1—C2	1.392 (6)	C11—H11B	0.9600
C1—C6	1.415 (6)	C11—H11C	0.9600
C2—C3	1.364 (7)	C12—C13	1.487 (7)
C2—H2	0.9300	C12—H12A	0.9700
C3—C4	1.376 (8)	C12—H12B	0.9700
C3—H3	0.9300	C13—C14	1.276 (8)
C4—C5	1.373 (7)	C13—H13	0.9300
C4—H4	0.9300	C14—H14A	0.9300
C5—C6	1.398 (6)	C14—H14B	0.9300
O4—S1—O3	118.8 (2)	C7—C8—C9	125.3 (4)
O4—S1—N1	108.66 (18)	C7—C8—S1	118.0 (3)
O3—S1—N1	107.72 (19)	C9—C8—S1	116.6 (4)
O4—S1—C8	108.2 (2)	O1—C9—O2	124.8 (5)
O3—S1—C8	111.5 (2)	O1—C9—C8	124.1 (5)
N1—S1—C8	100.3 (2)	O2—C9—C8	111.0 (4)
C9—O2—C10	117.4 (5)	O2—C10—H10A	109.5
C1—N1—C12	122.0 (3)	O2—C10—H10B	109.5
C1—N1—S1	115.7 (3)	H10A—C10—H10B	109.5
C12—N1—S1	121.4 (3)	O2—C10—H10C	109.5
C2—C1—N1	120.0 (4)	H10A—C10—H10C	109.5
C2—C1—C6	120.0 (4)	H10B—C10—H10C	109.5
N1—C1—C6	120.0 (3)	C7—C11—H11A	109.5
C3—C2—C1	120.5 (5)	C7—C11—H11B	109.5
C3—C2—H2	119.7	H11A—C11—H11B	109.5
C1—C2—H2	119.7	C7—C11—H11C	109.5
C2—C3—C4	120.3 (5)	H11A—C11—H11C	109.5
C2—C3—H3	119.9	H11B—C11—H11C	109.5
C4—C3—H3	119.9	N1—C12—C13	116.1 (4)
C5—C4—C3	120.3 (5)	N1—C12—H12A	108.3
C5—C4—H4	119.9	C13—C12—H12A	108.3
C3—C4—H4	119.9	N1—C12—H12B	108.3
C4—C5—C6	121.4 (5)	C13—C12—H12B	108.3
C4—C5—H5	119.3	H12A—C12—H12B	107.4
C6—C5—H5	119.3	C14—C13—C12	126.2 (5)
C5—C6—C1	117.4 (4)	C14—C13—H13	116.9
C5—C6—C7	121.5 (4)	C12—C13—H13	116.9
C1—C6—C7	120.8 (4)	C13—C14—H14A	120.0
C8—C7—C6	120.7 (4)	C13—C14—H14B	120.0
C8—C7—C11	121.0 (4)	H14A—C14—H14B	120.0
C6—C7—C11	118.3 (4)
O4—S1—N1—C1	−60.7 (3)	C1—C6—C7—C8	21.7 (6)
O3—S1—N1—C1	169.5 (3)	C5—C6—C7—C11	17.0 (6)
C8—S1—N1—C1	52.7 (3)	C1—C6—C7—C11	−156.7 (4)
O4—S1—N1—C12	130.1 (3)	C6—C7—C8—C9	−171.1 (4)
O3—S1—N1—C12	0.2 (4)	C11—C7—C8—C9	7.3 (7)
C8—S1—N1—C12	−116.5 (3)	C6—C7—C8—S1	7.8 (6)
C12—N1—C1—C2	−42.8 (5)	C11—C7—C8—S1	−173.9 (4)
S1—N1—C1—C2	147.9 (3)	O4—S1—C8—C7	72.8 (4)
C12—N1—C1—C6	136.3 (4)	O3—S1—C8—C7	−154.8 (3)
S1—N1—C1—C6	−32.9 (5)	N1—S1—C8—C7	−40.9 (4)
N1—C1—C2—C3	−178.4 (4)	O4—S1—C8—C9	−108.2 (4)
C6—C1—C2—C3	2.5 (6)	O3—S1—C8—C9	24.2 (4)
C1—C2—C3—C4	1.2 (7)	N1—S1—C8—C9	138.1 (3)
C2—C3—C4—C5	−3.6 (8)	C10—O2—C9—O1	5.4 (8)
C3—C4—C5—C6	2.4 (8)	C10—O2—C9—C8	−171.5 (5)
C4—C5—C6—C1	1.2 (7)	C7—C8—C9—O1	46.0 (7)
C4—C5—C6—C7	−172.6 (5)	S1—C8—C9—O1	−132.9 (5)
C2—C1—C6—C5	−3.6 (6)	C7—C8—C9—O2	−137.1 (5)
N1—C1—C6—C5	177.2 (4)	S1—C8—C9—O2	44.0 (5)
C2—C1—C6—C7	170.3 (4)	C1—N1—C12—C13	97.2 (5)
N1—C1—C6—C7	−8.9 (6)	S1—N1—C12—C13	−94.2 (4)
C5—C6—C7—C8	−164.7 (4)	N1—C12—C13—C14	3.5 (8)

D—H···A	D—H	H···A	D···A	D—H···A
C12—H12A···Cgi	0.97	2.95	3.576 (5)	123