7-Methoxy­anthra­[1,9-de]-1,3,2-dioxathiine-8,11-dione 2,2-dioxide

The title compound, C₁₅H₈O₇S, contains the first structurally characterized example of a cyclic sulfate grouping fused to an aromatic ring system.

S1. Comment

The title compound, (I), was prepared as an intermediate in the synthesis of carminomycinone systems (Cameron et al., 1989). It is an unusual example of a cyclic sulfate system fused to an aromatic array, and as such was considered worthy of structural confirmation and definition, as described here.

The results of the room-temperature single-crystal X-ray study are consistent in terms of stoichiometry and connectivity with the formulation proposed (Fig. 1). The fused C₁₄ carbocyclic ring system is essentially planar (χ² 2170) (Fig. 2); the molecules are stacked normal to the bc cell diagonal, with the methoxy methyl group projecting normal to the plane, presumably in consequence of the steric demands of atoms H6 and O8, which lie on opposite faces of the molecule; the S atom lies out of the plane by 0.637 (2) Å.

The geometry of the anthracenoid carbocyclic array in (I) (Table 1) can be compared with that of a usefully precise determination of the unsubstituted parent 1,4-anthraquinone (polymorph 1) also at room-temperature (Dzyabchenko & Zavodnik, 1984) and the corresponding values are generally very similar. In the quinonoid ring, the asymmetries in the exocyclic angles at atoms C8 and C11 are consistent, suggesting that the origin lies not in steric interactions with the substituents at atoms C1 and C7, but rather in the increased C7a—C11a separation compared with C9—C10; the latter is a typical double bond, and the former is greater than 1.427 (4) Å in both. Disparities are observed in the C1—C1a—C3—C4, string, in the associated angles, rather than the distances, presumably consequent upon the introduction of substituents at atoms C1 and C3; the angles at these atoms (C11a—C1—C1a and C1a—C3—C4) are slightly larger in (I) and the C1—C1a—C3 angle is slightly smaller. In both compounds, C7—C7a and C1—C11a lie well below 1.40 Å, with all distances in the C1—C1a—C6a—C7 string being above that value. In the non-quinonoid peripheral ring, the distances in the C3—C1a—C6a—-C6 string are all above 1.40 Å, and those in the C3—C6 string are close to or below that value, with considerable double-bond character in the C3—C4 and C5—C6 bonds, typical of naphthalene-type bond fixation.

The sulfate ring is essentially symmetrical about the quasi-mirror plane containing atoms C1a, S, O21 and O22; the angles at the C and O atoms are all greater than 116°, but the only O—S—O angle is just 101.15 (8)°, compensated by a greatly enlarged O21—S2—O22 angle between the two short S—O bonds. Torsion angles are given in Table 1. Compound (I) is the first example of a sulfate substituting a pair of aromatic sites, although there are a limited number of other examples of systems incorporating rigid support of other types. Nevertheless, O···O distances bridged by the simple polymethylene sequences (CH₂)_n, (for n=2, 3 or 4,), 2.32, 2.421 (3), 2.415 (3)/2.427 (3) Å, respectively (Boer et al., 1968; Lowe et al., 1988; Kruger et al., 1998), suggest the present value [O1···O3 = 2.433 (2) Å] to be relatively unstrained.

S2. Experimental

The synthesis is recorded in Cameron et al. (1989). Crystals (m.p. 210–213°) were obtained from light petroleum. Analysis found: C 54.2, H 2.5, S 9.7; C₁₅H₈O₇S requires C 54.2, H 2.4, S 9.6%. λ_max (log ε)236, 283 s h, 295 s h, 330 s h, 415 nm (4.70, 3.82, 3.80, 3.47, 3.71). ν_max 1660, 1618 cm⁻¹. δ 4,10, s, OCH₃; 6.98, s, H9, H10; 7.50, dd, J8, 1 Hz, H4; 7.84, t, J 8 Hz, H5; 8.31, dd, J 8, 1 Hz, H6. m/z 332 (M⁺ 100%).

S3. Refinement

H atoms were found in difference Fourier maps and were placed at idealized positions [C—H = 0.95 Å, U_iso(H) = 1.25U_eq(C) for CH and 1.5U_eq(C) for CH₃] and not refined.

Computing details

Data collection: Enraf Nonius software; cell refinement: Enraf Nonius software; data reduction: Xtal (Hall et al., 1995); program(s) used to solve structure: Xtal; program(s) used to refine structure: CRYLSQ in Xtal; molecular graphics: Xtal; software used to prepare material for publication: BONDLA CIFIO in Xtal.

Figures

	Fig. 1. Projection of a single molecule of (I) normal to the aromatic plane. Displacement ellipsoids are shown at the 20% probability level for non-H atoms and H atoms are shown as spheres of arbitrary radii (0.1 Å).
	Fig. 2. Unit-cell contents projected along c (H atoms have been omitted) showing the crystal packing.

(I)

Crystal data

C15H8O7S	Z = 2
Mr = 332.29	F(000) = 340
Triclinic, P1	Dx = 1.69 Mg m^−3
Hall symbol: -p 1	Mo Kα radiation, λ = 0.71073 Å
a = 9.359 (2) Å	Cell parameters from 6 reflections
b = 9.406 (2) Å	θ = 19.8–21.1°
c = 9.509 (2) Å	µ = 0.29 mm^−1
α = 68.05 (2)°	T = 293 K
β = 64.17 (2)°	Block, colourless
γ = 62.58 (1)°	0.42 × 0.2 × 0.2 mm
V = 652.9 (3) Å^3

Data collection

CAD4 diffractometer	θmax = 32.5°, θmin = 2.4°
Radiation source: sealed tube	h = 0→14
Graphite monochromator	k = −12→14
2θ–ω scans	l = −12→12
4485 measured reflections	6 standard reflections every 60 min
4485 independent reflections	intensity decay: none
3316 reflections with I > 3σ(I)

Refinement

Refinement on F	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.046	Hydrogen site location: difference Fourier map
wR(F^2) = 0.058	H-atom parameters not refined
S = 1.01	w = 1/(σ^2(Fo) + 0.0003F^2) where σ(I) = [σ(I)meas + .0004(Inet)^2]^1/2
3316 reflections	(Δ/σ)max = 0.001
208 parameters	Δρmax = 0.35 e Å^−3
0 restraints	Δρmin = −0.30 e Å^−3
0 constraints

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

	x	y	z	Uiso*/Ueq
C1	0.3823 (2)	0.2112 (2)	0.5455 (2)	0.0359 (18)
O1	0.26906 (18)	0.12588 (17)	0.62353 (16)	0.0455 (16)
S2	0.23601 (7)	0.05250 (6)	0.80860 (6)	0.0454 (5)
O21	0.1547 (2)	−0.0579 (2)	0.8497 (2)	0.066 (2)
O22	0.16749 (19)	0.17939 (19)	0.88886 (17)	0.0539 (18)
C1a	0.5196 (2)	0.1553 (2)	0.6018 (2)	0.0359 (17)
C3	0.5410 (2)	0.0253 (2)	0.7356 (2)	0.042 (2)
O3	0.42242 (19)	−0.05549 (17)	0.81311 (17)	0.0509 (17)
C4	0.6739 (3)	−0.0307 (3)	0.7897 (3)	0.052 (2)
C5	0.7948 (3)	0.0452 (3)	0.7077 (3)	0.057 (3)
C6	0.7818 (3)	0.1718 (3)	0.5773 (3)	0.051 (3)
C6a	0.6422 (2)	0.2309 (2)	0.5216 (2)	0.039 (2)
C7	0.6202 (2)	0.3638 (2)	0.3869 (2)	0.041 (2)
O7	0.7336 (2)	0.4408 (2)	0.32403 (18)	0.058 (2)
C71	0.8695 (3)	0.4004 (3)	0.1808 (3)	0.060 (3)
C7a	0.4844 (3)	0.4164 (2)	0.3340 (2)	0.041 (2)
C8	0.4577 (3)	0.5587 (3)	0.1968 (2)	0.053 (2)
O8	0.5579 (3)	0.6298 (2)	0.1170 (2)	0.084 (3)
C9	0.3013 (4)	0.6148 (3)	0.1590 (3)	0.067 (3)
C10	0.1890 (4)	0.5420 (3)	0.2342 (3)	0.064 (3)
C11	0.2098 (3)	0.3962 (3)	0.3635 (3)	0.049 (2)
O11	0.1078 (3)	0.3277 (3)	0.4229 (3)	0.077 (3)
C11a	0.3599 (2)	0.3379 (2)	0.4162 (2)	0.0376 (19)
H4	0.68402	−0.11937	0.88134	0.06400*
H5	0.88958	0.00812	0.74426	0.07200*
H6	0.86683	0.22145	0.52318	0.06300*
H71a	0.96936	0.31993	0.20716	0.09100*
H71b	0.89445	0.49549	0.11199	0.09100*
H71c	0.83934	0.35698	0.12603	0.09100*
H9	0.27972	0.71019	0.07486	0.08200*
H10	0.08889	0.58644	0.20276	0.08000*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
C1	0.0371 (8)	0.0379 (8)	0.0322 (8)	−0.0176 (7)	−0.0084 (6)	−0.0049 (6)
O1	0.0515 (8)	0.0524 (8)	0.0396 (7)	−0.0329 (6)	−0.0147 (6)	0.0017 (6)
S2	0.0486 (3)	0.0448 (2)	0.0395 (2)	−0.0262 (2)	−0.00916 (18)	0.00066 (17)
O21	0.0751 (11)	0.0650 (10)	0.0625 (10)	−0.0501 (9)	−0.0139 (8)	0.0041 (8)
O22	0.0515 (8)	0.0564 (9)	0.0454 (8)	−0.0217 (7)	−0.0065 (6)	−0.0102 (6)
C1a	0.0353 (8)	0.0358 (8)	0.0334 (8)	−0.0132 (6)	−0.0090 (6)	−0.0060 (6)
C3	0.0424 (9)	0.0381 (9)	0.0392 (9)	−0.0130 (7)	−0.0126 (7)	−0.0035 (7)
O3	0.0537 (8)	0.0386 (7)	0.0491 (8)	−0.0195 (6)	−0.0170 (6)	0.0065 (6)
C4	0.0509 (11)	0.0460 (10)	0.0511 (11)	−0.0061 (9)	−0.0248 (9)	−0.0058 (9)
C5	0.0429 (10)	0.0631 (13)	0.0642 (14)	−0.0070 (10)	−0.0257 (10)	−0.0170 (11)
C6	0.0366 (9)	0.0627 (13)	0.0550 (12)	−0.0182 (9)	−0.0101 (8)	−0.0195 (10)
C6a	0.0357 (8)	0.0426 (9)	0.0383 (8)	−0.0162 (7)	−0.0064 (7)	−0.0108 (7)
C7	0.0434 (9)	0.0426 (9)	0.0354 (8)	−0.0236 (8)	−0.0014 (7)	−0.0097 (7)
O7	0.0626 (9)	0.0716 (10)	0.0480 (8)	−0.0473 (8)	0.0034 (7)	−0.0161 (7)
C71	0.0499 (12)	0.0708 (15)	0.0536 (12)	−0.0341 (11)	0.0045 (9)	−0.0154 (11)
C7a	0.0493 (10)	0.0364 (8)	0.0303 (8)	−0.0183 (7)	−0.0069 (7)	−0.0040 (6)
C8	0.0652 (13)	0.0416 (10)	0.0362 (9)	−0.0191 (9)	−0.0084 (9)	−0.0012 (7)
O8	0.0746 (12)	0.0611 (11)	0.0699 (11)	−0.0302 (9)	−0.0070 (9)	0.0212 (9)
C9	0.097 (2)	0.0515 (13)	0.0490 (12)	−0.0249 (13)	−0.0389 (13)	0.0086 (10)
C10	0.0843 (18)	0.0560 (13)	0.0620 (14)	−0.0192 (12)	−0.0481 (14)	−0.0002 (11)
C11	0.0555 (11)	0.0500 (11)	0.0458 (10)	−0.0173 (9)	−0.0254 (9)	−0.0070 (8)
O11	0.0736 (12)	0.0884 (13)	0.0859 (13)	−0.0436 (11)	−0.0489 (10)	0.0111 (10)
C11a	0.0421 (9)	0.0383 (8)	0.0321 (8)	−0.0157 (7)	−0.0119 (7)	−0.0054 (6)

Geometric parameters (Å, º)

C1—O1	1.404 (3)	C6a—C7	1.428 (2)
C1—C1a	1.408 (3)	C7—O7	1.356 (3)
C1—C11a	1.369 (2)	C7—C7a	1.380 (3)
O1—S2	1.5759 (14)	O7—C71	1.431 (3)
S2—O21	1.405 (3)	C71—H71a	0.959
S2—O22	1.403 (2)	C71—H71b	0.951
S2—O3	1.5741 (17)	C71—H71c	0.955
C1a—C3	1.410 (2)	C7a—C8	1.493 (2)
C1a—C6a	1.410 (3)	C7a—C11a	1.443 (3)
C3—O3	1.414 (3)	C8—O8	1.217 (4)
C3—C4	1.356 (4)	C8—C9	1.468 (5)
C4—C5	1.399 (4)	C9—C10	1.314 (5)
C4—H4	0.959	C9—H9	0.961
C5—C6	1.366 (3)	C10—C11	1.461 (3)
C5—H5	0.960	C10—H10	0.965
C6—C6a	1.418 (4)	C11—O11	1.212 (4)
C6—H6	0.960	C11—C11a	1.492 (4)
O1—C1—C1a	117.06 (14)	C6a—C7—O7	115.4 (2)
O1—C1—C11a	119.7 (2)	C6a—C7—C7a	121.4 (2)
C1a—C1—C11a	123.2 (2)	O7—C7—C7a	123.01 (16)
C1—O1—S2	117.08 (17)	C7—O7—C71	117.1 (2)
O1—S2—O21	105.98 (12)	O7—C71—H71a	109.7
O1—S2—O22	109.70 (9)	O7—C71—H71b	110.1
O1—S2—O3	101.15 (8)	O7—C71—H71c	110.4
O21—S2—O22	122.14 (10)	H71a—C71—H71b	108.6
O21—S2—O3	106.17 (10)	H71a—C71—H71c	108.9
O22—S2—O3	109.64 (12)	H71b—C71—H71c	109.1
C1—C1a—C3	122.8 (2)	C7—C7a—C8	121.6 (2)
C1—C1a—C6a	119.18 (15)	C7—C7a—C11a	119.98 (16)
C3—C1a—C6a	118.0 (2)	C8—C7a—C11a	118.3 (2)
C1a—C3—O3	118.5 (2)	C7a—C8—O8	123.2 (3)
C1a—C3—C4	123.2 (2)	C7a—C8—C9	117.5 (2)
O3—C3—C4	118.23 (17)	O8—C8—C9	119.3 (2)
S2—O3—C3	116.04 (11)	C8—C9—C10	123.7 (2)
C3—C4—C5	117.9 (2)	C8—C9—H9	118.2
C3—C4—H4	120.8	C10—C9—H9	118.2
C5—C4—H4	121.3	C9—C10—C11	122.5 (3)
C4—C5—C6	121.9 (3)	C9—C10—H10	118.8
C4—C5—H5	119.4	C11—C10—H10	118.6
C6—C5—H5	118.7	C10—C11—O11	120.1 (3)
C5—C6—C6a	120.1 (2)	C10—C11—C11a	117.1 (2)
C5—C6—H6	120.1	O11—C11—C11a	122.83 (19)
C6a—C6—H6	119.7	C1—C11a—C7a	117.9 (2)
C1a—C6a—C6	118.81 (17)	C1—C11a—C11	121.4 (2)
C1a—C6a—C7	118.3 (2)	C7a—C11a—C11	120.71 (16)
C6—C6a—C7	122.9 (2)
C1a—C1—O1—S2	33.7 (2)	C5—C6—C6a—C1a	−0.9 (4)
C11a—C1—O1—S2	−149.08 (15)	C5—C6—C6a—C7	179.4 (2)
O1—C1—C1a—C3	−3.3 (3)	C1a—C6a—C7—O7	174.31 (18)
O1—C1—C1a—C6a	176.41 (17)	C1a—C6a—C7—C7a	−0.9 (3)
C11a—C1—C1a—C3	179.6 (2)	C6—C6a—C7—O7	−6.0 (3)
C11a—C1—C1a—C6a	−0.7 (3)	C6—C6a—C7—C7a	178.8 (2)
O1—C1—C11a—C7a	−176.64 (17)	C6a—C7—O7—C71	101.7 (2)
O1—C1—C11a—C11	4.7 (3)	C7a—C7—O7—C71	−83.1 (2)
C1a—C1—C11a—C7a	0.4 (3)	C6a—C7—C7a—C8	177.93 (19)
C1a—C1—C11a—C11	−178.2 (2)	C6a—C7—C7a—C11a	0.6 (3)
C1—O1—S2—O21	−166.00 (12)	O7—C7—C7a—C8	3.1 (3)
C1—O1—S2—O22	60.34 (15)	O7—C7—C7a—C11a	−174.23 (18)
C1—O1—S2—O3	−55.41 (14)	C7—C7a—C8—O8	5.0 (4)
O1—S2—O3—C3	53.3 (2)	C7—C7a—C8—C9	−174.5 (2)
O21—S2—O3—C3	163.71 (17)	C11a—C7a—C8—O8	−177.7 (2)
O22—S2—O3—C3	−62.54 (18)	C11a—C7a—C8—C9	2.8 (3)
C1—C1a—C3—O3	2.1 (3)	C7—C7a—C11a—C1	−0.3 (3)
C1—C1a—C3—C4	179.2 (2)	C7—C7a—C11a—C11	178.3 (2)
C6a—C1a—C3—O3	−177.62 (17)	C8—C7a—C11a—C1	−177.72 (19)
C6a—C1a—C3—C4	−0.5 (3)	C8—C7a—C11a—C11	0.9 (3)
C1—C1a—C6a—C6	−178.8 (2)	C7a—C8—C9—C10	−3.3 (4)
C1—C1a—C6a—C7	0.9 (3)	O8—C8—C9—C10	177.2 (3)
C3—C1a—C6a—C6	0.9 (3)	C8—C9—C10—C11	−0.3 (5)
C3—C1a—C6a—C7	−179.37 (19)	C9—C10—C11—O11	−175.6 (3)
C1a—C3—O3—S2	−31.0 (3)	C9—C10—C11—C11a	4.1 (4)
C4—C3—O3—S2	151.76 (18)	C10—C11—C11a—C1	174.2 (2)
C1a—C3—C4—C5	0.0 (4)	C10—C11—C11a—C7a	−4.3 (3)
O3—C3—C4—C5	177.2 (2)	O11—C11—C11a—C1	−6.0 (3)
C3—C4—C5—C6	−0.0 (4)	O11—C11—C11a—C7a	175.4 (2)
C4—C5—C6—C6a	0.5 (4)