2-Methoxy­methyl-1,3-di­thiol­ane 1,1,3,3-tetraoxide

The title compound, C₅H₁₀O₅S₂, consists of a five-membered di­thiol­ane ring with two O atoms bonded to each S atom and a methoxy­methyl group at the 2-position. The asymmetric unit contains two mol­ecules. A few interatomic close contacts seem to influence the geometry of the di­thiol­ane ring.

Key indicators

• Single-crystal X-ray study
• T = 293 K
• Mean [sigma](C-C) = 0.003 Å
• R factor = 0.037
• wR factor = 0.103
• Data-to-parameter ratio = 17.2

checkCIF results

No syntax errors found

ADDSYM reports no extra symmetry

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S1. Comment

Simple vinyl (Maignan & Raphael, 1983) or acetylenic (Maignan & Belkasmioui, 1988; Lee et al., 1988) sulfoxides are poor dienophiles, and show low levels of diastereocontrol, thereby limiting their synthetic use. The alkylation of a simple vinyl sulfoxide, however, gives rise to a much more reactive dienophile (Kagan & Ronan, 1991, 1992). Simple vinyl sulfoxides can also be made more reactive by the introduction of an additional electron-withdrawing group. 1,1-Bis(p-tolylsulfinyl)ethene (Arai et al., 1986) facilitates a highly stereoselective reaction with cyclopentadiene under Lewis acid catalysis in a Diels–Alder reaction.

In recent years, compounds having two geminal sulfones have been shown to be good dienophiles, and their Diels–Alder reactions have attracted considerable attention (Lucchi et al., 1992). The sulfonyl group has versatile functionality in organic synthesis and can be conveniently eliminated, resulting in an alkene (Little & Myong, 1980; Lopez & Carretero, 1991). Moreover, the sulfonyl group may undergo desulfonylation and oxidative desulfonylation with the formation of the corresponding ketones (Leon & Carretero, 1991).

C₂-symmetric cyclic alkenyl sulfoxides (Aggarwal et al., 1995) show high selectivity in Diels–Alder reactions. The Diels–Alder adducts may also be converted into bridged unsaturated ketones, for example, norbornenone, which is a useful intermediate for the synthesis of biologically important compounds.

Racemic 2-methoxymethyl-1,3-dithiolane 1,3-dioxide has been shown to be a useful starting material for the preparation of C₂-symmetric ketene equivalents (Aggarwal et al., 1998). The title compound, (I), may also be a useful starting material for the preparation of a new sulfone-containing dienophile.

The structure determination of (I) was undertaken in order to understand the effects of the methoxymethyl group and the O atoms on the geometry of the five-membered dithiolane ring, and to compare the results with those found in 1,2,3,4-tetrahydrocarbazole-1-spiro-2'-[1,3]dithiolane, (II) (Hökelek et al., 1994), N-(2-methoxyethyl)-N-{2,3,4,9-tetrahydrospiro- [1H-carbazole-1,2-[1,3]dithiolane]-4-yl}benzenesulfonamide, (III) (Patıret al., 1997), spiro[carbazole-1(2H),2'-[1,3]dithiolan]-4(3H)-one, (IV) (Hökelek et al., 1998), 9-acetonyl-3-ethyldiene-1,2,3,4-tetrahydrospiro[carbazole- 1,2'-[1,3]dithiolan]-4-one, (V) (Hökelek et al., 1999), and (1RS,3RS,αSR)-1,3-dioxo-α-phenyl-1,3-dithiolane-2-methanol, (VI) (Aggarwal et al., 1997).

The title compound, (I) (Fig. 1), consists of a five-membered dithiolane ring with two O atoms bonded to each S atom and a methoxymethyl group attached at the 2-position. The asymmetric unit consists of two molecules. The S atoms of the dithiolane ring have electron-releasing properties, but the O atoms bonded to S have electron-withdrawing properties, thereby influencing bond lengths and angles of the dithiolane ring (Table 1). It should be stressed, however, that the values are almost identical in both molecules.

Some significant changes in the geometry of the dithiolane ring are evident when a few bond angles are compared with the values found in compounds (II)–(VI) (Table 2).

The dithiolane rings are, of course, not planar. In each of the two molecules of the asymmetric unit, the conformation is half-chair. In one molecule, considering only the ring atoms and atoms O1–O4, there is a local twofold rotation axis passing through C1 and the mid-point of C2—C3.

The structure reveals a number of short contacts (Å): O2ⁱ···H11(C1) 2.24 (2), O1ⁱⁱ···H21(C2) 2.28 (3), O1'ⁱⁱⁱ···H31(C3) 2.45 (3), O1ⁱⁱⁱ···H32(C3) 2.46 (3), O4'^iv···H22'(C2') 2.47 (3), O2'^v···H11'(C1') 2.51 (3) and O2^vi···H31'(C3') 2.54 (3) [symmetry codes: (i) −x, −y + 2,- z + 1; (ii) x + 1, y, z; (iii) −x, −y + 1, −z + 1; (iv) −x − 2, −y, −z + 2; (v) −x − 1, −y, −z + 2; (vi) −x − 1, −y + 1, −z + 1]. These interactions play a role in determining the molecular conformation of each molecule.

S2. Experimental

The title compound, (I), was prepared, according to a literature method (Aggarwal et al., 1998), from racemic-2-methoxymethyl-1,3-dithiolane 1,3-dioxide (2.7 g, 14.8 mmol) in dry acetonitrile (10 ml) and purified m-CPBA (5.6 g, 32.6 mmol) in ether (50 ml), the mixture being stirred for 3 d at room temperature. Subsequently, a white solid was collected by filtration and crystallized from EtOAc (yield 2.3 g, 73%), m.p. 390 K.

S3. Refinement

The H-atom positions were located in a difference synthesis and refined isotropically.

Computing details

Data collection: XSCANS (Siemens, 1996); cell refinement: XSCANS; data reduction: SHELXTL (Bruker, 1997); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997); software used to prepare material for publication: WinGX publication routines (Farrugia, 1999).

Figures

Fig. 1. An ORTEP-3 (Farrugia, 1997) drawing of the title molecule with the atom-numbering scheme. Displacement ellipsoids are drawn at the 50% probability level.

2-Methoxymethyl-1,3-dithiolane 1,1,3,3-tetraoxide

Crystal data

C5H10O5S2	Z = 4
Mr = 214.25	F(000) = 448
Triclinic, P1	Dx = 1.620 Mg m^−3
Hall symbol: -P 1	Mo Kα radiation, λ = 0.71073 Å
a = 6.7699 (10) Å	Cell parameters from 25 reflections
b = 9.1736 (13) Å	θ = 10–15°
c = 14.5311 (19) Å	µ = 0.59 mm^−1
α = 77.910 (11)°	T = 293 K
β = 85.013 (11)°	Prism, colourless
γ = 86.886 (12)°	0.35 × 0.25 × 0.20 mm
V = 878.5 (2) Å^3

Data collection

Siemens P4 diffractometer	Rint = 0.032
Radiation source: fine-focus sealed tube	θmax = 30.0°, θmin = 1.4°
Graphite monochromator	h = 0→9
non–profiled ω scans	k = −12→12
5527 measured reflections	l = −20→20
5125 independent reflections	2 standard reflections every 50 reflections
4609 reflections with I > 2σ(I)	intensity decay: 1%

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)] = 0.037	All H-atom parameters refined
wR(F^2) = 0.103	w = 1/[σ^2(Fo^2) + (0.0491P)^2 + 0.3797P] where P = (Fo^2 + 2Fc^2)/3
S = 1.12	(Δ/σ)max = 0.001
5125 reflections	Δρmax = 0.70 e Å^−3
298 parameters	Δρmin = −0.43 e Å^−3
0 restraints	Extinction correction: SHELXL97, Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.077 (4)

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
H11	0.080 (3)	0.861 (2)	0.5810 (15)	0.032 (5)*
H32	0.261 (3)	0.577 (3)	0.4364 (15)	0.033 (5)*
H31	0.257 (4)	0.701 (3)	0.349 (2)	0.054 (7)*
H41'	−0.467 (5)	0.308 (3)	0.891 (2)	0.069 (8)*
H51'	−0.560 (6)	0.562 (4)	0.936 (3)	0.100 (12)*
H11'	−0.721 (3)	0.116 (3)	0.9613 (18)	0.043 (6)*
H42	−0.155 (4)	0.665 (3)	0.6361 (19)	0.054 (7)*
H21	0.552 (4)	0.707 (3)	0.4385 (17)	0.046 (6)*
H21'	−1.052 (4)	−0.017 (3)	0.7966 (19)	0.051 (7)*
H41	0.034 (4)	0.552 (3)	0.6574 (19)	0.057 (7)*
H22'	−0.947 (4)	−0.076 (3)	0.8890 (19)	0.052 (7)*
H42'	−0.626 (4)	0.354 (3)	0.8214 (19)	0.047 (7)*
H31'	−0.713 (4)	−0.116 (4)	0.771 (2)	0.068 (8)*
H32'	−0.758 (4)	0.050 (3)	0.718 (2)	0.062 (8)*
H22	0.424 (4)	0.852 (3)	0.4259 (18)	0.047 (6)*
H51	−0.137 (5)	0.679 (4)	0.858 (3)	0.084 (10)*
H52'	−0.788 (6)	0.596 (4)	0.962 (3)	0.091 (11)*
H53'	−0.729 (5)	0.591 (4)	0.855 (3)	0.098 (13)*
H52	−0.291 (8)	0.675 (6)	0.794 (4)	0.135 (18)*
H53	−0.149 (5)	0.535 (5)	0.820 (3)	0.092 (11)*
S1	0.03484 (6)	0.75288 (4)	0.45759 (3)	0.02964 (11)
S2'	−0.96229 (6)	0.16515 (5)	0.86322 (3)	0.03316 (11)
S1'	−0.56738 (6)	0.03167 (5)	0.83906 (3)	0.03333 (11)
S2	0.37186 (6)	0.72763 (5)	0.57137 (3)	0.03454 (11)
C1	0.1041 (2)	0.76086 (18)	0.57463 (11)	0.0294 (3)
O1	−0.12218 (19)	0.65123 (17)	0.46501 (10)	0.0434 (3)
O2	0.0040 (2)	0.90410 (15)	0.40803 (10)	0.0482 (4)
O2'	−0.5049 (2)	−0.09416 (17)	0.90770 (11)	0.0503 (4)
C3	0.2598 (2)	0.67979 (19)	0.41120 (12)	0.0314 (3)
C1'	−0.7129 (3)	0.1595 (2)	0.90059 (12)	0.0325 (3)
O3	0.4112 (2)	0.57355 (18)	0.61281 (11)	0.0516 (4)
O4'	−1.1054 (2)	0.16727 (19)	0.94196 (11)	0.0513 (4)
O3'	−0.9746 (2)	0.27897 (16)	0.77932 (11)	0.0482 (3)
O1'	−0.4189 (2)	0.1115 (2)	0.77474 (11)	0.0550 (4)
C2'	−0.9511 (3)	−0.0111 (2)	0.83097 (14)	0.0378 (4)
C3'	−0.7546 (3)	−0.0220 (3)	0.77515 (13)	0.0398 (4)
O5'	−0.7444 (3)	0.39508 (18)	0.93943 (13)	0.0564 (4)
O5	−0.0060 (3)	0.70611 (18)	0.73632 (10)	0.0512 (4)
C2	0.4231 (3)	0.7548 (2)	0.44704 (13)	0.0367 (3)
O4	0.4615 (2)	0.8401 (2)	0.60728 (12)	0.0577 (4)
C4	−0.0141 (3)	0.6557 (2)	0.65228 (13)	0.0388 (4)
C4'	−0.6260 (3)	0.3129 (2)	0.88228 (17)	0.0471 (4)
C5	−0.1551 (6)	0.6408 (4)	0.8056 (2)	0.0670 (8)
C5'	−0.6988 (7)	0.5484 (3)	0.9188 (3)	0.0763 (9)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
S1	0.02937 (19)	0.02793 (18)	0.03225 (19)	0.00579 (13)	−0.00780 (14)	−0.00714 (14)
S2'	0.0332 (2)	0.0349 (2)	0.0309 (2)	0.00354 (15)	−0.00221 (14)	−0.00710 (15)
S1'	0.0301 (2)	0.0416 (2)	0.02823 (19)	0.00257 (15)	−0.00227 (14)	−0.00809 (15)
S2	0.0304 (2)	0.0412 (2)	0.0347 (2)	0.00355 (15)	−0.00834 (15)	−0.01283 (16)
C1	0.0306 (7)	0.0273 (7)	0.0314 (7)	0.0033 (5)	−0.0040 (6)	−0.0091 (6)
O1	0.0305 (6)	0.0530 (8)	0.0499 (8)	−0.0050 (5)	−0.0072 (5)	−0.0151 (6)
O2	0.0701 (10)	0.0316 (6)	0.0424 (7)	0.0178 (6)	−0.0194 (7)	−0.0058 (5)
O2'	0.0587 (9)	0.0492 (8)	0.0423 (7)	0.0177 (7)	−0.0148 (6)	−0.0086 (6)
C3	0.0309 (7)	0.0328 (8)	0.0315 (7)	0.0009 (6)	−0.0014 (6)	−0.0101 (6)
C1'	0.0356 (8)	0.0369 (8)	0.0260 (7)	0.0005 (6)	−0.0044 (6)	−0.0082 (6)
O3	0.0501 (8)	0.0521 (9)	0.0480 (8)	0.0208 (7)	−0.0104 (6)	−0.0030 (6)
O4'	0.0423 (8)	0.0638 (10)	0.0477 (8)	0.0056 (7)	0.0086 (6)	−0.0180 (7)
O3'	0.0589 (9)	0.0411 (7)	0.0420 (7)	0.0050 (6)	−0.0168 (6)	0.0010 (6)
O1'	0.0435 (8)	0.0708 (11)	0.0481 (8)	−0.0099 (7)	0.0123 (6)	−0.0108 (7)
C2'	0.0359 (9)	0.0390 (9)	0.0400 (9)	−0.0023 (7)	−0.0034 (7)	−0.0113 (7)
C3'	0.0386 (9)	0.0512 (11)	0.0336 (8)	0.0046 (8)	−0.0057 (7)	−0.0181 (8)
O5'	0.0707 (11)	0.0422 (8)	0.0617 (10)	−0.0006 (7)	−0.0063 (8)	−0.0229 (7)
O5	0.0679 (10)	0.0540 (9)	0.0332 (7)	−0.0185 (7)	0.0089 (6)	−0.0133 (6)
C2	0.0297 (8)	0.0423 (9)	0.0386 (9)	−0.0034 (7)	−0.0009 (6)	−0.0099 (7)
O4	0.0453 (8)	0.0783 (12)	0.0626 (10)	−0.0119 (8)	−0.0094 (7)	−0.0397 (9)
C4	0.0421 (9)	0.0404 (9)	0.0343 (8)	−0.0069 (7)	0.0010 (7)	−0.0092 (7)
C4'	0.0508 (11)	0.0419 (10)	0.0514 (12)	−0.0077 (8)	−0.0041 (9)	−0.0141 (9)
C5	0.087 (2)	0.0612 (16)	0.0493 (13)	−0.0149 (14)	0.0291 (13)	−0.0145 (11)
C5'	0.110 (3)	0.0417 (13)	0.084 (2)	0.0035 (14)	−0.032 (2)	−0.0199 (13)

Geometric parameters (Å, º)

S1—O1	1.4342 (14)	C1'—H11'	0.89 (2)
S1—O2	1.4363 (14)	C2'—C3'	1.506 (3)
S1—C3	1.7671 (17)	C2'—H21'	0.89 (3)
S1—C1	1.8199 (16)	C2'—H22'	0.93 (3)
S2'—O3'	1.4347 (14)	C3'—H31'	0.90 (3)
S2'—O4'	1.4361 (15)	C3'—H32'	0.94 (3)
S2'—C2'	1.7714 (19)	O5'—C4'	1.407 (3)
S2'—C1'	1.8125 (18)	O5'—C5'	1.420 (3)
S1'—O2'	1.4296 (15)	O5—C4	1.400 (2)
S1'—O1'	1.4320 (15)	O5—C5	1.424 (3)
S1'—C3'	1.7820 (19)	C2—H21	0.97 (3)
S1'—C1'	1.8185 (17)	C2—H22	0.88 (3)
S2—O4	1.4327 (15)	C4—H42	0.99 (3)
S2—O3	1.4359 (16)	C4—H41	0.98 (3)
S2—C2	1.7772 (19)	C4'—H41'	1.09 (3)
S2—C1	1.8197 (17)	C4'—H42'	0.89 (3)
C1—C4	1.522 (2)	C5—H51	0.92 (4)
C1—H11	0.94 (2)	C5—H52	0.97 (5)
C3—C2	1.517 (2)	C5—H53	0.95 (4)
C3—H32	0.93 (2)	C5'—H51'	1.02 (4)
C3—H31	0.88 (3)	C5'—H52'	0.98 (4)
C1'—C4'	1.518 (3)	C5'—H53'	0.97 (4)
O1—S1—O2	118.48 (9)	C3'—C2'—H21'	111.3 (17)
O1—S1—C3	111.07 (8)	S2'—C2'—H21'	109.6 (17)
O2—S1—C3	108.80 (9)	C3'—C2'—H22'	108.7 (16)
O1—S1—C1	110.05 (8)	S2'—C2'—H22'	102.0 (16)
O2—S1—C1	107.00 (8)	H21'—C2'—H22'	118 (2)
C3—S1—C1	99.74 (8)	C2'—C3'—S1'	107.96 (13)
O3'—S2'—O4'	119.33 (10)	C2'—C3'—H31'	114 (2)
O3'—S2'—C2'	108.49 (10)	S1'—C3'—H31'	101.5 (19)
O4'—S2'—C2'	110.67 (10)	C2'—C3'—H32'	107.8 (18)
O3'—S2'—C1'	108.19 (9)	S1'—C3'—H32'	106.2 (18)
O4'—S2'—C1'	110.18 (9)	H31'—C3'—H32'	118 (3)
C2'—S2'—C1'	97.80 (9)	C4'—O5'—C5'	112.2 (2)
O2'—S1'—O1'	118.19 (11)	C4—O5—C5	110.92 (19)
O2'—S1'—C3'	109.45 (10)	C3—C2—S2	106.13 (12)
O1'—S1'—C3'	109.89 (10)	C3—C2—H21	113.0 (15)
O2'—S1'—C1'	108.25 (9)	S2—C2—H21	104.9 (15)
O1'—S1'—C1'	109.67 (10)	C3—C2—H22	113.7 (16)
C3'—S1'—C1'	99.81 (8)	S2—C2—H22	106.0 (17)
O4—S2—O3	118.90 (11)	H21—C2—H22	112 (2)
O4—S2—C2	110.46 (10)	O5—C4—C1	107.72 (15)
O3—S2—C2	108.94 (10)	O5—C4—H42	107.8 (16)
O4—S2—C1	109.93 (9)	C1—C4—H42	107.3 (15)
O3—S2—C1	108.07 (9)	O5—C4—H41	112.6 (16)
C2—S2—C1	98.60 (8)	C1—C4—H41	111.7 (16)
C4—C1—S2	115.07 (12)	H42—C4—H41	109 (2)
C4—C1—S1	112.20 (12)	O5'—C4'—C1'	106.16 (18)
S2—C1—S1	105.83 (8)	O5'—C4'—H41'	115.7 (16)
C4—C1—H11	110.6 (13)	C1'—C4'—H41'	112.9 (16)
S2—C1—H11	106.3 (13)	O5'—C4'—H42'	112.5 (17)
S1—C1—H11	106.2 (13)	C1'—C4'—H42'	109.5 (17)
C2—C3—S1	105.61 (12)	H41'—C4'—H42'	100 (2)
C2—C3—H32	111.5 (13)	O5—C5—H51	105 (2)
S1—C3—H32	105.6 (13)	O5—C5—H52	116 (3)
C2—C3—H31	113.9 (18)	H51—C5—H52	101 (4)
S1—C3—H31	106.6 (18)	O5—C5—H53	114 (2)
H32—C3—H31	113 (2)	H51—C5—H53	111 (3)
C4'—C1'—S2'	112.57 (14)	H52—C5—H53	109 (4)
C4'—C1'—S1'	112.62 (13)	O5'—C5'—H51'	111 (2)
S2'—C1'—S1'	106.20 (9)	O5'—C5'—H52'	106 (2)
C4'—C1'—H11'	112.6 (16)	H51'—C5'—H52'	105 (3)
S2'—C1'—H11'	106.0 (15)	O5'—C5'—H53'	109 (2)
S1'—C1'—H11'	106.3 (16)	H51'—C5'—H53'	117 (3)
C3'—C2'—S2'	106.31 (13)	H52'—C5'—H53'	108 (3)
O4—S2—C1—C4	−105.37 (15)	O1'—S1'—C1'—C4'	−9.08 (17)
O3—S2—C1—C4	25.86 (15)	C3'—S1'—C1'—C4'	−124.45 (15)
C2—S2—C1—C4	139.11 (13)	O2'—S1'—C1'—S2'	−115.19 (10)
O4—S2—C1—S1	130.13 (10)	O1'—S1'—C1'—S2'	114.57 (11)
O3—S2—C1—S1	−98.64 (10)	C3'—S1'—C1'—S2'	−0.80 (11)
C2—S2—C1—S1	14.61 (10)	O3'—S2'—C2'—C3'	67.42 (16)
O1—S1—C1—C4	1.79 (15)	O4'—S2'—C2'—C3'	−159.87 (13)
O2—S1—C1—C4	131.76 (14)	C1'—S2'—C2'—C3'	−44.79 (15)
C3—S1—C1—C4	−115.02 (13)	S2'—C2'—C3'—S1'	48.07 (17)
O1—S1—C1—S2	128.06 (9)	O2'—S1'—C3'—C2'	84.73 (16)
O2—S1—C1—S2	−101.98 (10)	O1'—S1'—C3'—C2'	−143.93 (15)
C3—S1—C1—S2	11.25 (10)	C1'—S1'—C3'—C2'	−28.73 (16)
O1—S1—C3—C2	−154.90 (12)	S1—C3—C2—S2	52.20 (14)
O2—S1—C3—C2	72.96 (14)	O4—S2—C2—C3	−156.35 (13)
C1—S1—C3—C2	−38.87 (13)	O3—S2—C2—C3	71.32 (15)
O3'—S2'—C1'—C4'	35.54 (16)	C1—S2—C2—C3	−41.24 (14)
O4'—S2'—C1'—C4'	−96.53 (15)	C5—O5—C4—C1	163.8 (2)
C2'—S2'—C1'—C4'	148.00 (14)	S2—C1—C4—O5	79.95 (18)
O3'—S2'—C1'—S1'	−88.14 (11)	S1—C1—C4—O5	−158.96 (13)
O4'—S2'—C1'—S1'	139.79 (10)	C5'—O5'—C4'—C1'	−170.9 (2)
C2'—S2'—C1'—S1'	24.32 (11)	S2'—C1'—C4'—O5'	64.30 (19)
O2'—S1'—C1'—C4'	121.16 (15)	S1'—C1'—C4'—O5'	−175.66 (14)