(E)-3-Methoxy-3-methyl­sulfanyl­iso­thio­chroman-4-one oxime

The title compound, C₁₁H₁₃NO₂S₂, (II), is formed from methanol trapping of the cyclic cation derived from 1-methyl­thio-1-benzyl­thio-2-nitro­ethyl­ene (I), in triflic acid. Compound (II) is characterized by its E-configured oxime and the boat conformation of its non-aromatic ring.

Key indicators

• Single-crystal X-ray study
• T = 120 K
• Mean [sigma](C-C) = 0.002 Å
• R factor = 0.036
• wR factor = 0.043
• Data-to-parameter ratio = 15.9

checkCIF results

No syntax errors found

ADDSYM reports no extra symmetry

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S1. Comment

In trifluoromethanesulfonic acid, 1,1-bis(methylthio)-2-nitroethene undergoes polyprotonation that leads to loss of water and formation of the hydroxynitrilium ion (O-protonated nitrile oxide). This cation is an electrophile that is able to react with a tethered aromatic ring, either intermolecularily or intramolecularily (Coustard, 1995). In this way, when a solution of 1-methylthio-1-benzylthio-2-nitroethylene, (I), in trifluoromethanesulfonic acid was quenched with methanol, the title compound, (II), was obtained in a good yield (Coustard, 2001). A view of this molecule is presented Fig. 1.

The non-aromatic ring adopts a slighly distorted boat conformation with torsion angles C9—C8—S1—C7 and C9—C1—C6—C7 of -3.4 (2) and 2.7 (4)°, respectively. The C8 atom of the ortholactone function is bonded to an axial MeS group [C11—S2—C8—S1 - 173.65 (8)° and N1—C9—C8—S2 - 114.67 (13)°] and to an equatorial MeO group [O2—C8—C9—C1 - 171.08 (12)°].

The C9, N1, and O1 atoms of the oxime function and the aromatic ring are not coplanar, as seen in the torsion angle C2—C1—C9—N1 of 57.3 (4)°. The oxime function is E configured [C1—C9—N1—O1 0.1 (3)°] with an unusually short C9—N1 bond of 1.2559 (9) Å as compared with the mean value of 1.280 (13) Å for Csp³═N—OH (Allen et al., 1987). The observed oxime configuration (Hegarty et al., 1980, 1991) is in agreement with the postulated mechanism of formation which implied electrophilic addition of the transient hydroxynitrilium ion on the phenyl ring.

S2. Experimental

The title compound was prepared by cyclization of 1-ethylthio-1-benzylthio-2-nitroethylene, (I), in trifluotomethanesulfonic acid and quenching with methanol (Coustard, 2001). Crystallization from ethyl acetate afforded colourless crystals suitable for X-ray analysis.

S3. Refinement

H atoms bonded to C atoms were placed geometrically and their positional parameters were not refined. O-bonded H atoms were located from a difference map but their positional parameters were not refined. Displacement parameters were refined for all H atoms.

Computing details

Data collection: DENZO (Otwinowski & Minor, 1997), COLLECT (Nonius, 1998); cell refinement: DENZO; data reduction: DENZO; program(s) used to solve structure: SHELXS86 (Sheldrick, 1985); program(s) used to refine structure: CRYSTALS (Watkin, Prout, Carruthers & Betteridge, 1996); molecular graphics: CAMERON (Watkin, Prout & Pearce, 1996); software used to prepare material for publication: CRYSTALS.

Figures

Fig. 1. A view of the title compound with the atomic numbering scheme. Displacement ellipsoids are drawn at the 50% probability level.

(E)-3-methoxy-3-methylsulfanylisothiochroman-4-one oxime

Crystal data

C11H13NO2S2	Dx = 1.46 Mg m^−3
Mr = 255.35	Melting point: 138.5 (dec.) K
Orthorhombic, Pbca	Mo Kα radiation, λ = 0.71073 Å
a = 9.3725 (2) Å	Cell parameters from 16060 reflections
b = 10.7012 (2) Å	θ = 1–28°
c = 23.0919 (4) Å	µ = 0.44 mm^−1
V = 2316.0 Å^3	T = 120 K
Z = 8	Plate, colourless
F(000) = 1073.97	0.30 × 0.20 × 0.20 mm

Data collection

Nonius KappaCCD diffractometer	Rint = 0.044
Graphite monochromator	θmax = 28.0°, θmin = 1.0°
ϕ rotation scans with 2° steps	h = 0→12
16060 measured reflections	k = 0→14
2823 independent reflections	l = 0→30
2317 reflections with I > 3σ(I)

Refinement

Refinement on F	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F^2 > 2σ(F^2)] = 0.036	Only H-atom displacement parameters refined
wR(F^2) = 0.043	Chebychev polynomial with 3 parameters (Carruthers & Watkin, 1979): 0.668, 0.599, 0.382
S = 1.06	(Δ/σ)max < 0.001
2317 reflections	Δρmax = 0.86 e Å^−3
146 parameters	Δρmin = −0.48 e Å^−3
Primary atom site location: structure-invariant direct methods

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

	x	y	z	Uiso*/Ueq
S1	0.05819 (5)	−0.11183 (4)	0.389587 (17)	0.0258
S2	−0.22159 (4)	−0.21074 (4)	0.373388 (16)	0.0231
O1	0.05499 (12)	−0.5552 (1)	0.43741 (4)	0.0229
O2	−0.09002 (13)	−0.2232 (1)	0.47471 (5)	0.0219
N1	−0.00388 (13)	−0.43753 (12)	0.44816 (5)	0.0183
C1	0.05424 (15)	−0.39098 (13)	0.34967 (6)	0.0176
C2	0.00356 (16)	−0.49106 (14)	0.31756 (6)	0.0199
C3	0.05603 (17)	−0.50977 (16)	0.26373 (7)	0.0253
C4	0.1594 (2)	−0.43021 (17)	0.24260 (7)	0.0292
C5	0.21119 (19)	−0.33152 (18)	0.27437 (7)	0.0300
C6	0.15805 (17)	−0.31031 (15)	0.32804 (6)	0.0222
C7	0.20824 (18)	−0.20566 (17)	0.36504 (7)	0.0270
C8	−0.06304 (16)	−0.23405 (14)	0.41668 (6)	0.0188
C9	−0.00210 (15)	−0.36337 (14)	0.40602 (6)	0.0167
C10	−0.1580 (2)	−0.11057 (16)	0.49207 (7)	0.0278
C11	−0.34419 (19)	−0.31788 (17)	0.40594 (8)	0.0309
H1	0.0514	−0.5889	0.4709	0.0376 (19)*
H21	−0.0705	−0.5485	0.3339	0.0476 (19)*
H31	0.0201	−0.5807	0.2394	0.0476 (19)*
H41	0.1982	−0.4452	0.2028	0.0476 (19)*
H51	0.2870	−0.2763	0.2581	0.0476 (19)*
H71	0.2654	−0.2297	0.3993	0.0376 (19)*
H72	0.2696	−0.1475	0.3454	0.0376 (19)*
H101	−0.1728	−0.1114	0.5349	0.0476 (19)*
H102	−0.2524	−0.1037	0.4721	0.0476 (19)*
H103	−0.0969	−0.0377	0.4811	0.0476 (19)*
H111	−0.4376	−0.3138	0.3855	0.0476 (19)*
H112	−0.3575	−0.2954	0.4477	0.0476 (19)*
H113	−0.3046	−0.4047	0.4033	0.0476 (19)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
S1	0.0324 (2)	0.0201 (2)	0.02511 (19)	−0.00553 (15)	0.00588 (15)	−0.00090 (13)
S2	0.0247 (2)	0.0227 (2)	0.02191 (18)	0.00285 (13)	−0.00431 (13)	0.00188 (14)
O1	0.0327 (6)	0.0199 (5)	0.0161 (4)	0.0080 (4)	0.0035 (4)	0.0022 (4)
O2	0.0295 (6)	0.0211 (5)	0.0152 (5)	0.0037 (4)	0.0009 (4)	0.0005 (4)
N1	0.0211 (6)	0.0184 (6)	0.0152 (5)	0.0039 (5)	0.0010 (4)	0.0002 (4)
C1	0.0180 (6)	0.0205 (7)	0.0142 (6)	0.0022 (5)	0.0010 (5)	0.0008 (5)
C2	0.0217 (6)	0.0211 (7)	0.0170 (6)	0.0016 (5)	−0.0005 (5)	0.0012 (5)
C3	0.0303 (8)	0.0288 (8)	0.0169 (6)	0.0041 (7)	−0.0023 (5)	−0.0028 (5)
C4	0.0341 (8)	0.0350 (8)	0.0184 (7)	0.0037 (7)	0.0058 (6)	−0.0005 (6)
C5	0.0326 (8)	0.0345 (9)	0.0230 (7)	−0.0026 (7)	0.0109 (6)	0.0012 (7)
C6	0.0214 (7)	0.0271 (7)	0.0180 (6)	−0.0018 (6)	0.0018 (5)	0.0013 (5)
C7	0.0229 (7)	0.0325 (8)	0.0254 (7)	−0.0087 (6)	0.0050 (6)	−0.0041 (6)
C8	0.0230 (7)	0.0198 (7)	0.0134 (6)	0.0008 (5)	0.0007 (5)	0.0007 (5)
C9	0.0164 (6)	0.0194 (7)	0.0144 (6)	−0.0003 (5)	0.0000 (5)	0.0005 (5)
C10	0.0359 (9)	0.0244 (8)	0.0229 (7)	0.0035 (7)	0.0041 (6)	−0.0058 (6)
C11	0.0245 (8)	0.0322 (9)	0.0360 (9)	−0.0028 (7)	0.0001 (7)	−0.0007 (7)

Geometric parameters (Å, º)

S1—C7	1.8186 (18)	C3—H31	1.0028 (16)
S1—C8	1.8420 (15)	C4—C5	1.374 (3)
S2—C8	1.8083 (15)	C4—H41	1.0011 (15)
S2—C11	1.7888 (19)	C5—C6	1.355 (2)
O1—N1	1.3971 (16)	C5—H51	0.9979 (17)
O1—H1	0.854 (1)	C6—C7	1.485 (2)
O2—C8	1.3684 (17)	C7—H71	0.9901 (18)
O2—C10	1.4212 (19)	C7—H72	0.9614 (16)
N1—C9	1.2559 (19)	C8—C9	1.517 (2)
C1—C2	1.387 (2)	C10—H101	0.9976 (16)
C1—C6	1.393 (2)	C10—H102	1.0008 (18)
C1—C9	1.4348 (19)	C10—H103	0.9999 (18)
C2—C3	1.352 (2)	C11—H111	0.9951 (19)
C2—H21	1.0009 (15)	C11—H112	1.0028 (19)
C3—C4	1.379 (2)	C11—H113	1.0021 (19)
C7—S1—C8	101.00 (7)	C1—C6—C5	118.74 (15)
C8—S2—C11	101.96 (8)	C1—C6—C7	118.83 (14)
N1—O1—H1	101.8 (1)	C5—C6—C7	122.42 (15)
C8—O2—C10	115.54 (12)	C6—C7—H71	115.81 (16)
O1—N1—C9	115.25 (12)	C6—C7—H72	113.97 (15)
C2—C1—C6	121.74 (14)	H71—C7—H72	102.84 (15)
C2—C1—C9	121.20 (13)	O2—C8—C9	107.81 (11)
C6—C1—C9	117.03 (13)	N1—C9—C1	125.27 (14)
C1—C2—C3	118.79 (15)	N1—C9—C8	116.46 (12)
C1—C2—H21	120.65 (14)	C1—C9—C8	118.27 (12)
C3—C2—H21	120.56 (15)	O2—C10—H101	109.51 (15)
C2—C3—C4	119.31 (15)	O2—C10—H102	109.19 (14)
C2—C3—H31	120.35 (16)	H101—C10—H102	109.60 (17)
C4—C3—H31	120.34 (15)	O2—C10—H103	109.43 (15)
C3—C4—C5	122.26 (15)	H101—C10—H103	109.68 (16)
C3—C4—H41	118.76 (17)	H102—C10—H103	109.42 (16)
C5—C4—H41	118.98 (17)	H111—C11—H112	109.65 (17)
C4—C5—C6	119.15 (16)	H111—C11—H113	109.71 (17)
C4—C5—H51	120.33 (16)	H112—C11—H113	109.09 (18)
C6—C5—H51	120.52 (18)
C9—C8—S1—C7	−3.4 (2)	O2—C8—C9—C1	−171.08 (12)
C9—C1—C6—C7	2.7 (4)	C11—S2—C8—S1	−173.65 (8)
C11—S2—C8—S1	−173.65 (8)	C2—C1—C9—N1	57.3 (4)
N1—C9—C8—S2	−114.67 (13)	C1—C9—N1—O1	0.1 (3)