(3aSR,9aSR)-3a,4,9,9a-Tetra­hydro-4-[(1SR)-1-methoxy­ethyl]-2-methyl-4,9-[1',2']­benzeno-1H-benzo­[f]­iso­indole-1,3-(2H)-dione

The title compound, C₂₂H₂₁NO₃, has a molecular structure with a rigid polycyclic nucleus, in which a carbox­amide ring bridges the two CH positions of the central ring of anthracene. The 1-methoxy­ethyl substituent, by contrast, has conform­ational freedom and adopts an orientation minimizing steric and electronic repulsions with the carbox­amide group.

Key indicators

• Single-crystal X-ray study
• T = 160 K
• Mean [sigma](C-C) = 0.003 Å
• R factor = 0.048
• wR factor = 0.120
• Data-to-parameter ratio = 12.8

checkCIF results

No syntax errors found

ADDSYM reports no extra symmetry

---

S1. Comment

The title compound, (I), was prepared as part of a study of diastereoselective Diels–Alder addition reactions of chiral anthracene derivatives substituted at one of the central ring C atoms (Atherton & Jones, 2002). The primary purpose of the structure determination was to confirm the relative stereochemistry, as evidence for the proposed mechanism of the reaction. Both the starting material and the product (I) of the Diels–Alder reaction are racemic; (I) crystallizes in a centrosymmetric space group.

The molecular structure (Fig. 1) is essentially the same as that of the corresponding acid anhydride (Clegg & Harrington, 2002), in which an O atom takes the place of the NMe group in the title compound. This similarity extends to the orientation of the conformationally flexible 1-methoxyethyl substituent, which gives almost ideal staggering around the C9—C20 bond (Table 1), confirming that this is a molecular preference and is not affected by the crystal-packing arrangement, which is quite different in the two structures. There are only van der Waals interactions between molecules. The difference in size of the O and NMe groups in the anhydride and carboxamide, respectively, does not allow the two compounds to be isomorphous.

The Cambridge Structural Database (CSD, Version 5.23, April 2002, and 3 updates; Allen, 2002) contains as many as 16 structures with a carboxamide group bridging the 9,10-positions of an anthracene molecule, although these include different solvates or cocrystals of the same compound (Weber et al., 1991, 1994, 1995; Kim, Hubig et al., 2001; Kim, Lindeman & Kochi, 2001; Kishikawa et al., 1997). The rigidity of the polycyclic core of these molecules is demonstrated by the small range of dihedral (hinge) angles found between pairs of mean planes defined as follows: plane 1 is the carboxamide group; plane 2 is C9/C10/C15/C16 (using the atom numbering for the title compound); plane 3 is C9/C10/C13/C14; plane 4 is C9/C10/C11/C12. Dihedral angles for the previously reported carboxamide structures lie in the ranges: 117.4–120.7° for planes 1–2; 116.3–120.3° for planes 2–3 and 2–4; 122.3–125.7° for planes 3—4. The corresponding values for (I) are: 122.15 (8) (1–2), 119.08 (10) (2–3), 116.79 (9)(2–4) and 124.12 (8)° (3–4), each of them within or marginally outside the range for the other structures. In these and other aspects, the molecular structure of (I) closely resembles that of the corresponding anhydride (Clegg & Harrington, 2002). The benzene rings are essentially coplanar with planes 3 and 4; the respective dihedral angles in (I), demonstrating only very minor hinge folding at the ring fusions, are 177.45 (8) and 177.59 (15)°, with 180° corresponding to exact coplanarity.

S2. Experimental

The synthesis has been described by Atherton & Jones (2002).

S3. Refinement

H atoms were placed geometrically and refined with a riding model (including free rotation about C—C bonds), and with U_iso constrained to be 1.2 (1.5 for methyl groups) times U_eq of the carrier atom.

Computing details

Data collection: SMART (Bruker, 2001); cell refinement: SAINT (Bruker, 2001); data reduction: SAINT; program(s) used to solve structure: SHELXTL (Sheldrick, 2001); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL and local programs.

Figures

Fig. 1. The molecular structure of (I) with atom labels and 50% probability ellipsoids for non-H atoms.

(3aSR,9aSR)-3a,4,9,9a-Tetrahydro-4-[(1SR)-1-methoxyethyl]-2-methyl- 4,9-[1',2-]benzeno-1H-benzo[f]isoindole-1,3-(2H)-dione

Crystal data

C22H21NO3	F(000) = 736
Mr = 347.40	Dx = 1.327 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
a = 10.7625 (7) Å	Cell parameters from 11489 reflections
b = 9.6850 (6) Å	θ = 2.2–28.8°
c = 16.7021 (11) Å	µ = 0.09 mm^−1
β = 93.067 (2)°	T = 160 K
V = 1738.45 (19) Å^3	Block, colourless
Z = 4	0.70 × 0.50 × 0.50 mm

Data collection

Bruker SMART 1K CCD diffractometer	2619 reflections with I > 2σ(I)
Radiation source: sealed tube	Rint = 0.026
Graphite monochromator	θmax = 25.0°, θmin = 1.9°
Detector resolution: 8.192 pixels mm^-1	h = −12→12
ω rotation with narrow frames scans	k = −11→11
12142 measured reflections	l = −19→19
3052 independent reflections

Refinement

Refinement on F^2	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)] = 0.048	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.120	H-atom parameters constrained
S = 1.04	w = 1/[σ^2(Fo^2) + (0.0496P)^2 + 1.7203P] where P = (Fo^2 + 2Fc^2)/3
3052 reflections	(Δ/σ)max = 0.007
238 parameters	Δρmax = 0.30 e Å^−3
0 restraints	Δρmin = −0.25 e Å^−3

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

	x	y	z	Uiso*/Ueq
O1	0.39364 (16)	0.06693 (15)	0.59256 (9)	0.0359 (4)
O2	0.14344 (13)	0.44479 (15)	0.58331 (9)	0.0282 (4)
O3	0.27339 (13)	0.67858 (14)	0.45050 (8)	0.0240 (3)
N1	0.25668 (15)	0.24617 (17)	0.60150 (10)	0.0219 (4)
C1	0.44223 (18)	0.5523 (2)	0.32845 (11)	0.0207 (4)
H1	0.3981	0.6373	0.3266	0.025*
C2	0.55211 (19)	0.5387 (2)	0.28857 (12)	0.0252 (5)
H2	0.5817	0.6144	0.2589	0.030*
C3	0.61868 (19)	0.4162 (2)	0.29167 (12)	0.0254 (5)
H3	0.6934	0.4083	0.2642	0.030*
C4	0.57638 (18)	0.3051 (2)	0.33489 (11)	0.0218 (4)
H4	0.6221	0.2212	0.3377	0.026*
C5	0.2284 (2)	0.0579 (2)	0.37724 (12)	0.0253 (5)
H5	0.2784	−0.0230	0.3790	0.030*
C6	0.1023 (2)	0.0503 (2)	0.35392 (14)	0.0321 (5)
H6	0.0667	−0.0355	0.3375	0.039*
C7	0.0289 (2)	0.1674 (2)	0.35468 (13)	0.0299 (5)
H7	−0.0576	0.1603	0.3406	0.036*
C8	0.07952 (18)	0.2952 (2)	0.37576 (11)	0.0229 (4)
H8	0.0279	0.3747	0.3770	0.027*
C9	0.27960 (17)	0.43606 (19)	0.41988 (11)	0.0178 (4)
C10	0.41384 (18)	0.2074 (2)	0.42616 (11)	0.0197 (4)
H10	0.4635	0.1201	0.4260	0.024*
C11	0.39754 (17)	0.4408 (2)	0.37094 (11)	0.0180 (4)
C12	0.46653 (18)	0.3181 (2)	0.37391 (11)	0.0189 (4)
C13	0.27991 (18)	0.1852 (2)	0.39778 (11)	0.0198 (4)
C14	0.20703 (18)	0.3054 (2)	0.39509 (11)	0.0190 (4)
C15	0.41397 (17)	0.27458 (19)	0.51105 (11)	0.0183 (4)
H15	0.5010	0.2996	0.5295	0.022*
C16	0.33161 (17)	0.40542 (19)	0.50851 (11)	0.0165 (4)
H16	0.3821	0.4860	0.5288	0.020*
C17	0.35846 (19)	0.1810 (2)	0.57182 (12)	0.0221 (4)
C18	0.23127 (17)	0.3739 (2)	0.56683 (11)	0.0193 (4)
C19	0.1862 (2)	0.1889 (3)	0.66551 (15)	0.0378 (6)
H19A	0.2434	0.1453	0.7056	0.057*
H19B	0.1275	0.1198	0.6433	0.057*
H19C	0.1403	0.2629	0.6908	0.057*
C20	0.19957 (17)	0.5675 (2)	0.41610 (12)	0.0199 (4)
H20	0.1273	0.5526	0.4504	0.024*
C21	0.1482 (2)	0.6085 (2)	0.33183 (13)	0.0276 (5)
H21A	0.2049	0.5758	0.2919	0.041*
H21B	0.1410	0.7092	0.3285	0.041*
H21C	0.0660	0.5666	0.3214	0.041*
C22	0.2052 (2)	0.7647 (2)	0.50130 (13)	0.0307 (5)
H22A	0.1791	0.7109	0.5471	0.046*
H22B	0.1317	0.8010	0.4712	0.046*
H22C	0.2580	0.8416	0.5206	0.046*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.0473 (10)	0.0270 (9)	0.0346 (9)	0.0126 (7)	0.0130 (7)	0.0109 (7)
O2	0.0239 (8)	0.0319 (8)	0.0299 (8)	0.0084 (7)	0.0104 (6)	0.0040 (6)
O3	0.0236 (7)	0.0195 (7)	0.0291 (8)	0.0007 (6)	0.0041 (6)	−0.0034 (6)
N1	0.0228 (9)	0.0224 (9)	0.0209 (9)	−0.0012 (7)	0.0069 (7)	0.0031 (7)
C1	0.0218 (10)	0.0240 (10)	0.0160 (9)	−0.0011 (8)	−0.0008 (8)	0.0013 (8)
C2	0.0264 (11)	0.0324 (12)	0.0169 (10)	−0.0066 (9)	0.0025 (8)	0.0045 (8)
C3	0.0207 (10)	0.0378 (12)	0.0181 (10)	−0.0020 (9)	0.0056 (8)	−0.0015 (9)
C4	0.0184 (10)	0.0282 (11)	0.0189 (10)	0.0027 (8)	0.0014 (8)	−0.0032 (8)
C5	0.0288 (11)	0.0235 (11)	0.0243 (11)	−0.0030 (9)	0.0092 (9)	−0.0035 (8)
C6	0.0332 (12)	0.0304 (12)	0.0333 (12)	−0.0124 (10)	0.0064 (10)	−0.0109 (10)
C7	0.0208 (11)	0.0408 (13)	0.0281 (11)	−0.0098 (10)	0.0026 (9)	−0.0092 (10)
C8	0.0199 (10)	0.0307 (11)	0.0183 (10)	−0.0013 (9)	0.0034 (8)	−0.0024 (8)
C9	0.0163 (9)	0.0207 (10)	0.0163 (9)	0.0005 (8)	0.0014 (7)	0.0009 (8)
C10	0.0208 (10)	0.0187 (10)	0.0199 (10)	0.0011 (8)	0.0034 (8)	−0.0012 (8)
C11	0.0174 (9)	0.0222 (10)	0.0141 (9)	−0.0017 (8)	−0.0005 (7)	−0.0028 (7)
C12	0.0196 (10)	0.0227 (10)	0.0142 (9)	−0.0020 (8)	0.0000 (7)	−0.0024 (8)
C13	0.0223 (10)	0.0226 (10)	0.0150 (9)	−0.0019 (8)	0.0060 (8)	−0.0008 (8)
C14	0.0212 (10)	0.0252 (10)	0.0111 (9)	−0.0017 (8)	0.0049 (7)	−0.0013 (8)
C15	0.0168 (9)	0.0202 (10)	0.0179 (10)	0.0007 (8)	0.0011 (7)	−0.0008 (8)
C16	0.0164 (9)	0.0175 (9)	0.0156 (9)	0.0003 (7)	0.0015 (7)	−0.0006 (7)
C17	0.0251 (10)	0.0224 (11)	0.0187 (10)	0.0027 (8)	−0.0004 (8)	−0.0007 (8)
C18	0.0185 (10)	0.0211 (10)	0.0182 (10)	−0.0004 (8)	0.0000 (8)	−0.0016 (8)
C19	0.0386 (13)	0.0365 (13)	0.0403 (14)	0.0004 (11)	0.0197 (11)	0.0115 (11)
C20	0.0167 (9)	0.0211 (10)	0.0222 (10)	0.0000 (8)	0.0021 (8)	0.0005 (8)
C21	0.0249 (11)	0.0286 (11)	0.0289 (11)	0.0055 (9)	−0.0024 (9)	0.0041 (9)
C22	0.0368 (12)	0.0237 (11)	0.0320 (12)	0.0047 (10)	0.0061 (10)	−0.0038 (9)

Geometric parameters (Å, º)

O1—C17	1.212 (2)	C9—C14	1.532 (3)
O2—C18	1.212 (2)	C9—C16	1.582 (3)
O3—C20	1.439 (2)	C9—C20	1.536 (3)
O3—C22	1.421 (2)	C10—H10	1.000
N1—C17	1.379 (3)	C10—C12	1.512 (3)
N1—C18	1.387 (3)	C10—C13	1.508 (3)
N1—C19	1.454 (3)	C10—C15	1.560 (3)
C1—H1	0.950	C11—C12	1.401 (3)
C1—C2	1.394 (3)	C13—C14	1.404 (3)
C1—C11	1.392 (3)	C15—H15	1.000
C2—H2	0.950	C15—C16	1.546 (3)
C2—C3	1.385 (3)	C15—C17	1.508 (3)
C3—H3	0.950	C16—H16	1.000
C3—C4	1.386 (3)	C16—C18	1.523 (3)
C4—H4	0.950	C19—H19A	0.980
C4—C12	1.386 (3)	C19—H19B	0.980
C5—H5	0.950	C19—H19C	0.980
C5—C6	1.394 (3)	C20—H20	1.000
C5—C13	1.387 (3)	C20—C21	1.537 (3)
C6—H6	0.950	C21—H21A	0.980
C6—C7	1.382 (3)	C21—H21B	0.980
C7—H7	0.950	C21—H21C	0.980
C7—C8	1.390 (3)	C22—H22A	0.980
C8—H8	0.950	C22—H22B	0.980
C8—C14	1.396 (3)	C22—H22C	0.980
C9—C11	1.547 (3)
C20—O3—C22	112.69 (15)	C5—C13—C14	120.94 (18)
C17—N1—C18	113.64 (16)	C10—C13—C14	114.49 (17)
C17—N1—C19	123.04 (17)	C8—C14—C9	126.98 (18)
C18—N1—C19	123.28 (17)	C8—C14—C13	119.28 (18)
H1—C1—C2	120.2	C9—C14—C13	113.62 (16)
H1—C1—C11	120.2	C10—C15—H15	109.7
C2—C1—C11	119.66 (19)	C10—C15—C16	110.15 (15)
C1—C2—H2	119.5	C10—C15—C17	112.32 (15)
C1—C2—C3	120.90 (19)	H15—C15—C16	109.7
H2—C2—C3	119.5	H15—C15—C17	109.7
C2—C3—H3	120.0	C16—C15—C17	105.31 (15)
C2—C3—C4	120.03 (18)	C9—C16—C15	110.67 (14)
H3—C3—C4	120.0	C9—C16—H16	109.3
C3—C4—H4	120.4	C9—C16—C18	114.10 (15)
C3—C4—C12	119.13 (19)	C15—C16—H16	109.3
H4—C4—C12	120.4	C15—C16—C18	104.09 (15)
H5—C5—C6	120.5	H16—C16—C18	109.3
H5—C5—C13	120.5	O1—C17—N1	123.81 (19)
C6—C5—C13	119.1 (2)	O1—C17—C15	127.67 (19)
C5—C6—H6	119.9	N1—C17—C15	108.52 (16)
C5—C6—C7	120.2 (2)	O2—C18—N1	123.31 (18)
H6—C6—C7	119.9	O2—C18—C16	128.34 (18)
C6—C7—H7	119.5	N1—C18—C16	108.35 (16)
C6—C7—C8	121.06 (19)	N1—C19—H19A	109.5
H7—C7—C8	119.5	N1—C19—H19B	109.5
C7—C8—H8	120.4	N1—C19—H19C	109.5
C7—C8—C14	119.27 (19)	H19A—C19—H19B	109.5
H8—C8—C14	120.4	H19A—C19—H19C	109.5
C11—C9—C14	107.61 (15)	H19B—C19—H19C	109.5
C11—C9—C16	103.93 (14)	O3—C20—C9	107.87 (14)
C11—C9—C20	115.34 (15)	O3—C20—H20	108.0
C14—C9—C16	104.33 (14)	O3—C20—C21	109.65 (16)
C14—C9—C20	113.35 (15)	C9—C20—H20	108.0
C16—C9—C20	111.30 (15)	C9—C20—C21	115.17 (16)
H10—C10—C12	112.4	H20—C20—C21	108.0
H10—C10—C13	112.4	C20—C21—H21A	109.5
H10—C10—C15	112.4	C20—C21—H21B	109.5
C12—C10—C13	107.55 (15)	C20—C21—H21C	109.5
C12—C10—C15	104.27 (15)	H21A—C21—H21B	109.5
C13—C10—C15	107.43 (15)	H21A—C21—H21C	109.5
C1—C11—C9	127.44 (17)	H21B—C21—H21C	109.5
C1—C11—C12	118.64 (17)	O3—C22—H22A	109.5
C9—C11—C12	113.87 (16)	O3—C22—H22B	109.5
C4—C12—C10	124.25 (18)	O3—C22—H22C	109.5
C4—C12—C11	121.62 (18)	H22A—C22—H22B	109.5
C10—C12—C11	114.05 (16)	H22A—C22—H22C	109.5
C5—C13—C10	124.55 (18)	H22B—C22—H22C	109.5
C11—C1—C2—C3	−1.1 (3)	C20—C9—C14—C8	−4.5 (3)
C1—C2—C3—C4	−0.1 (3)	C20—C9—C14—C13	179.50 (16)
C2—C3—C4—C12	0.7 (3)	C12—C10—C15—C16	60.37 (19)
C13—C5—C6—C7	−2.7 (3)	C12—C10—C15—C17	177.41 (15)
C5—C6—C7—C8	2.3 (3)	C13—C10—C15—C16	−53.58 (19)
C6—C7—C8—C14	1.1 (3)	C13—C10—C15—C17	63.5 (2)
C2—C1—C11—C9	178.90 (17)	C10—C15—C16—C9	−3.6 (2)
C2—C1—C11—C12	1.5 (3)	C10—C15—C16—C18	119.44 (16)
C14—C9—C11—C1	131.77 (19)	C17—C15—C16—C9	−124.89 (16)
C14—C9—C11—C12	−50.7 (2)	C17—C15—C16—C18	−1.88 (19)
C16—C9—C11—C1	−118.0 (2)	C11—C9—C16—C15	−54.15 (18)
C16—C9—C11—C12	59.54 (19)	C11—C9—C16—C18	−171.14 (15)
C20—C9—C11—C1	4.1 (3)	C14—C9—C16—C15	58.50 (18)
C20—C9—C11—C12	−178.35 (15)	C14—C9—C16—C18	−58.49 (19)
C3—C4—C12—C10	−176.89 (18)	C20—C9—C16—C15	−178.90 (15)
C3—C4—C12—C11	−0.2 (3)	C20—C9—C16—C18	64.1 (2)
C1—C11—C12—C4	−0.9 (3)	C18—N1—C17—O1	−177.73 (19)
C1—C11—C12—C10	176.11 (16)	C18—N1—C17—C15	1.9 (2)
C9—C11—C12—C4	−178.63 (16)	C19—N1—C17—O1	4.8 (3)
C9—C11—C12—C10	−1.6 (2)	C19—N1—C17—C15	−175.58 (19)
C13—C10—C12—C4	−128.85 (19)	C10—C15—C17—O1	59.9 (3)
C13—C10—C12—C11	54.2 (2)	C10—C15—C17—N1	−119.72 (17)
C15—C10—C12—C4	117.28 (19)	C16—C15—C17—O1	179.8 (2)
C15—C10—C12—C11	−59.6 (2)	C16—C15—C17—N1	0.2 (2)
C6—C5—C13—C10	178.25 (18)	C17—N1—C18—O2	177.69 (18)
C6—C5—C13—C14	−0.2 (3)	C17—N1—C18—C16	−3.2 (2)
C12—C10—C13—C5	127.1 (2)	C19—N1—C18—O2	−4.9 (3)
C12—C10—C13—C14	−54.3 (2)	C19—N1—C18—C16	174.29 (19)
C15—C10—C13—C5	−121.2 (2)	C9—C16—C18—O2	−57.2 (3)
C15—C10—C13—C14	57.4 (2)	C9—C16—C18—N1	123.74 (17)
C7—C8—C14—C9	−179.80 (18)	C15—C16—C18—O2	−177.90 (19)
C7—C8—C14—C13	−4.0 (3)	C15—C16—C18—N1	3.00 (19)
C5—C13—C14—C8	3.6 (3)	C22—O3—C20—C9	−137.70 (16)
C5—C13—C14—C9	179.93 (17)	C22—O3—C20—C21	96.17 (19)
C10—C13—C14—C8	−175.00 (16)	C11—C9—C20—O3	−62.8 (2)
C10—C13—C14—C9	1.3 (2)	C11—C9—C20—C21	60.0 (2)
C11—C9—C14—C8	−133.29 (19)	C14—C9—C20—O3	172.54 (14)
C11—C9—C14—C13	50.7 (2)	C14—C9—C20—C21	−64.7 (2)
C16—C9—C14—C8	116.7 (2)	C16—C9—C20—O3	55.30 (19)
C16—C9—C14—C13	−59.25 (19)	C16—C9—C20—C21	178.10 (16)