2-Acetyl-4H-benzo­thia­zin-3(2H)-one

The title compound, C₁₀H₉NO₂S, has a boat-shaped heterocyclic six-membered ring such that the S and N atoms lie essentially in the plane of the benzene ring while the remaining two C atoms are above this plane.

S1. Comment

4H-1,4-Benzothiazines have been reported to possess a wide spectrum of pharmacological properties similar to phenothiazines (Krapcho, 1976; Keyzer et al., 1992; Chihara et al., 1984; Corona et al., 1992; Hiroyuki et al., 1990). These products constitute an interesting series of heterocyclic compounds, not only from their biological activities, but also for structural investigations

The structure of the title compound, (I), was assigned on the basis of NMR and IR spectroscopy, and mass spectrometry, and by X-ray crystallography in order to establish its structure in the solid state. The S and N atoms of the six-membered heterocyclic ring lie almost in the plane of the benzene ring, such that the dihedral angle between the mean C₆ and SCCN planes is 176.4 (6)°. The other two C atoms of the heterocylic ring lie 0.4806 (3) and 1.0163 (3) Å above the SCCN mean plane. This corresponds to a boat conformation for the ring.

S2. Experimental

Dithioanilin (10 g, 0.04 mol) was refluxed in a 250 ml two-necked round-bottomed flask equipped with a reflux condenser and a dropping funnel. Then ethyl acetoacetate (0.08 mol) in xylol (15 ml) was added dropwise. After 1.5 h the reaction was stopped, the solvent volume was reduced and the solution was allowed to settle. The product obtained was filtered off, washed with ether and recrystallized from ethanol (yield: 60%, m.p.: 447–449 K).

S3. Refinement

The difference Fourier maps showed that the methyl H atoms attached to the C14 atom have two equilibrium positions with an equal occupancy of 0.5.

Computing details

Data collection: KappaCCD software; data reduction: DENZO and SCALEPAK (Otwinowski & Minor, 1997); program(s) used to solve structure: SIR92 (Altomare et al., 1994); program(s) used to refine structure: maXus (Mackay et al., 1999); software used to prepare material for publication: maXus.

(I)

Crystal data

C10H9NO2S	F(000) = 432
Mr = 207.25	Dx = 1.448 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
a = 11.384 (1) Å	Cell parameters from 6857 reflections
b = 10.202 (1) Å	θ = 1–26.4°
c = 14.942 (2) Å	µ = 0.31 mm^−1
β = 146.816 (6)°	T = 298 K
V = 950.0 (9) Å^3	Cube, colourless
Z = 4	0.35 × 0.30 × 0.30 mm

Data collection

KappaCCD diffractometer	Rint = 0.023
Radiation source: fine-focus sealed tube	θmax = 26.4°
ϕ scan	h = −14→14
2011 measured reflections	k = −12→0
1900 independent reflections	l = −18→14
1741 reflections with I > 3σ(I)

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: geom, diff
R[F^2 > 2σ(F^2)] = 0.032	H-atom parameters not refined
wR(F^2) = 0.045	Weighting scheme based on measured s.u.'s w = 1/[σ^2(Fo^2) + 0.03Fo^2]
S = 1.18	(Δ/σ)max = 0.005
1741 reflections	Δρmax = 0.22 e Å^−3
127 parameters	Δρmin = −0.26 e Å^−3
Primary atom site location: structure-invariant direct methods

Special details

Refinement. Refinement on F².

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

	x	y	z	Uiso*/Ueq	Occ. (<1)
S1	−0.04468 (2)	0.036131 (13)	0.859442 (14)	0.06158 (5)
O2	0.24298 (4)	−0.07377 (3)	0.82898 (3)	0.0763 (2)
O3	−0.04470 (5)	0.20333 (3)	0.64665 (4)	0.1068 (2)
N4	0.34585 (5)	0.08011 (3)	0.99404 (4)	0.0552 (2)
C5	0.19747 (6)	0.00268 (3)	0.86074 (4)	0.0545 (2)
C6	−0.03175 (5)	0.01477 (3)	0.74704 (4)	0.0503 (2)
C7	−0.14659 (6)	0.12712 (4)	0.62642 (5)	0.0633 (2)
C8	0.31115 (6)	0.17569 (3)	1.03816 (4)	0.0499 (2)
C9	0.13345 (6)	0.16913 (3)	0.98148 (4)	0.0494 (2)
C10	0.43311 (7)	0.36795 (4)	1.19302 (5)	0.0832 (2)
C11	0.46010 (6)	0.27535 (4)	1.14367 (5)	0.0680 (2)
C12	0.10690 (6)	0.26411 (4)	1.03062 (5)	0.0671 (2)
C13	0.25574 (7)	0.36276 (4)	1.13566 (5)	0.0867 (3)
C14	−0.38369 (7)	0.13880 (4)	0.48812 (5)	0.0721 (2)
H6	−0.10365	−0.06503	0.68514	0.05000*
H10	0.53741	0.43635	1.26702	0.05000*
H11	0.58220	0.28005	1.18247	0.05000*
H12	−0.01580	0.26021	0.99123	0.05000*
H13	0.23664	0.42786	1.16916	0.05000*
H14A	−0.43519	0.21360	0.42272	0.05000*	0.50
H14B	−0.41539	0.14950	0.53032	0.05000*	0.50
H14C	−0.45279	0.06110	0.42212	0.05000*	0.50
H4	0.47015	0.07481	1.04544	0.05000*
H14D	−0.45009	0.05500	0.48402	0.05000*	0.50
H14E	−0.41409	0.22720	0.49872	0.05000*	0.50
H14F	−0.44999	0.13910	0.38022	0.05000*	0.50

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
S1	0.03280 (5)	0.03968 (5)	0.03646 (5)	−0.00362 (4)	0.03083 (5)	−0.00045 (4)
O2	0.0398 (2)	0.0418 (2)	0.0488 (2)	−0.00110 (10)	0.0390 (2)	−0.00850 (10)
O3	0.0585 (2)	0.0556 (2)	0.0666 (2)	0.0033 (2)	0.0546 (2)	0.0165 (2)
N4	0.0256 (2)	0.0380 (2)	0.0342 (2)	−0.00050 (10)	0.0257 (2)	−0.00380 (10)
C5	0.0307 (2)	0.0293 (2)	0.0326 (2)	0.0018 (2)	0.0275 (2)	0.0022 (2)
C6	0.0274 (2)	0.0278 (2)	0.0299 (2)	−0.0016 (2)	0.0243 (2)	−0.0020 (2)
C7	0.0388 (2)	0.0334 (2)	0.0352 (2)	0.0006 (2)	0.0325 (2)	0.0003 (2)
C8	0.0288 (2)	0.0308 (2)	0.0267 (2)	0.0026 (2)	0.0238 (2)	0.0026 (2)
C9	0.0284 (2)	0.0317 (2)	0.0257 (2)	0.0033 (2)	0.0230 (2)	0.0037 (2)
C10	0.0548 (3)	0.0402 (2)	0.0420 (3)	−0.0126 (2)	0.0408 (3)	−0.0118 (2)
C11	0.0378 (2)	0.0437 (2)	0.0373 (2)	−0.0096 (2)	0.0323 (2)	−0.0072 (2)
C12	0.0374 (2)	0.0468 (2)	0.0351 (2)	0.0081 (2)	0.0313 (2)	0.0038 (2)
C13	0.0579 (3)	0.0422 (3)	0.0441 (3)	0.0051 (2)	0.0439 (3)	−0.0024 (2)
C14	0.0378 (2)	0.0465 (3)	0.0368 (2)	0.0073 (2)	0.0284 (2)	0.0067 (2)

Geometric parameters (Å, º)

S1—C6	1.8181 (5)	C7—C14	1.4948 (8)
S1—C9	1.7579 (5)	C8—C9	1.3952 (6)
O2—C5	1.2299 (6)	C8—C11	1.3864 (7)
O3—C7	1.2061 (6)	C9—C12	1.3928 (7)
N4—C5	1.3462 (6)	C10—C11	1.3823 (8)
N4—C8	1.4060 (6)	C10—C13	1.3852 (9)
C5—C6	1.5134 (7)	C12—C13	1.3771 (8)
C6—C7	1.5251 (7)
C6—S1—C9	97.84 (2)	N4—C8—C9	121.16 (5)
C5—N4—C8	127.16 (4)	N4—C8—C11	119.11 (4)
O2—C5—N4	121.89 (4)	C9—C8—C11	119.91 (5)
O2—C5—C6	120.41 (4)	S1—C9—C8	119.60 (4)
N4—C5—C6	117.58 (4)	S1—C9—C12	120.92 (4)
S1—C6—C5	111.68 (3)	C8—C9—C12	119.39 (5)
S1—C6—C7	110.51 (3)	C11—C10—C13	120.18 (5)
C5—C6—C7	110.81 (4)	C8—C11—C10	120.13 (5)
O3—C7—C6	119.72 (5)	C9—C12—C13	120.46 (5)
O3—C7—C14	122.68 (5)	C10—C13—C12	119.95 (5)
C6—C7—C14	117.65 (4)