![e logo](https://journals.iucr.org/logos/jicons/e_36x36.png)
![Open Access](/logos/buttonlogos/open.png)
![...](/logos/entities/ctdot_rmgif.gif)
![...](/logos/entities/ctdot_rmgif.gif)
Supporting information
![]() | Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536808033849/hb2803sup1.cif |
![]() | Structure factor file (CIF format) https://doi.org/10.1107/S1600536808033849/hb2803Isup2.hkl |
CCDC reference: 709387
Key indicators
- Single-crystal X-ray study
- T = 100 K
- Mean
(C-C) = 0.002 Å
- R factor = 0.041
- wR factor = 0.094
- Data-to-parameter ratio = 16.6
checkCIF/PLATON results
No syntax errors found
Alert level G PLAT860_ALERT_3_G Note: Number of Least-Squares Restraints ....... 1
0 ALERT level A = In general: serious problem 0 ALERT level B = Potentially serious problem 0 ALERT level C = Check and explain 1 ALERT level G = General alerts; check 0 ALERT type 1 CIF construction/syntax error, inconsistent or missing data 0 ALERT type 2 Indicator that the structure model may be wrong or deficient 1 ALERT type 3 Indicator that the structure quality may be low 0 ALERT type 4 Improvement, methodology, query or suggestion 0 ALERT type 5 Informative message, check
1-Hydroxycarbazole (1, 0.001 mol) and 3,3-dimethylacrylicacid (0.001 mol) was dissolved in an ice-cold mixture of AlCl3/POCl3 (400 mg/ 6 ml) and were kept at room temperature for 24 h. Reaction monitoring by TLC indicated the formation of two compounds. After the completion of reaction (disappearance of starting material), the residue was poured onto ice water. The solid that separated out was filtered, dried and then separated by column chromatography on silica gel using petroleum ether/ ethyl acetate (98:2) as eluants to yield 2-(3,3-dimethylacryloyl)-1-hydroxycarbazole (2) and 2,2-dimethyl-2,3-dihydropyrano-[2,3-a] carbazol-4(11H)-one (3), respectively as yellow prisms. The product 3 thus separated was recrystallized from ethanol (0.106 g, 40%), m.p. 472–474 K.
The amine H atom was located in a difference map and was refined with an N—H distance restraint of 0.88 (2) Å and Uiso = 1.2 Ueq(N). All other hydrogen atoms were added in calculated positions with C—H bond distances of 0.99 (methylene), 0.95 (aromatic) and 0.98 Å (methyl). They were refined as riding with Uiso(H) = 1.2Ueq(C) or 1.5Ueq(methyl C).
Data collection: APEX2 (Bruker, 2007); cell refinement: SAINT (Bruker, 2007); data reduction: SAINT (Bruker, 2007); program(s) used to solve structure: SHELXTL (Version 6.14; Sheldrick, 2008); program(s) used to refine structure: SHELXTL (Version 6.14; Sheldrick, 2008); molecular graphics: Mercury (Version 2.0; Macrae et al., 2006); software used to prepare material for publication: SHELXTL (Version 6.14; Sheldrick, 2008).
C17H15NO2 | F(000) = 560 |
Mr = 265.30 | Dx = 1.313 Mg m−3 |
Monoclinic, P21/n | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -P 2yn | Cell parameters from 4649 reflections |
a = 5.9926 (5) Å | θ = 2.6–27.5° |
b = 14.3368 (12) Å | µ = 0.09 mm−1 |
c = 15.6839 (13) Å | T = 100 K |
β = 95.270 (1)° | Plate, yellow |
V = 1341.78 (19) Å3 | 0.37 × 0.19 × 0.16 mm |
Z = 4 |
Bruker APEX CCD diffractometer | 3083 independent reflections |
Radiation source: fine-focus sealed tube | 2630 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.026 |
ω scans | θmax = 27.5°, θmin = 1.9° |
Absorption correction: multi-scan (SADABS; Bruker, 2007) | h = −7→7 |
Tmin = 0.887, Tmax = 0.986 | k = −18→18 |
12548 measured reflections | l = −20→20 |
Refinement on F2 | Primary atom site location: structure-invariant direct methods |
Least-squares matrix: full | Secondary atom site location: difference Fourier map |
R[F2 > 2σ(F2)] = 0.041 | Hydrogen site location: difmap and geom |
wR(F2) = 0.094 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.06 | w = 1/[σ2(Fo2) + (0.035P)2 + 0.4678P] where P = (Fo2 + 2Fc2)/3 |
3083 reflections | (Δ/σ)max < 0.001 |
186 parameters | Δρmax = 0.20 e Å−3 |
1 restraint | Δρmin = −0.19 e Å−3 |
C17H15NO2 | V = 1341.78 (19) Å3 |
Mr = 265.30 | Z = 4 |
Monoclinic, P21/n | Mo Kα radiation |
a = 5.9926 (5) Å | µ = 0.09 mm−1 |
b = 14.3368 (12) Å | T = 100 K |
c = 15.6839 (13) Å | 0.37 × 0.19 × 0.16 mm |
β = 95.270 (1)° |
Bruker APEX CCD diffractometer | 3083 independent reflections |
Absorption correction: multi-scan (SADABS; Bruker, 2007) | 2630 reflections with I > 2σ(I) |
Tmin = 0.887, Tmax = 0.986 | Rint = 0.026 |
12548 measured reflections |
R[F2 > 2σ(F2)] = 0.041 | 1 restraint |
wR(F2) = 0.094 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.06 | Δρmax = 0.20 e Å−3 |
3083 reflections | Δρmin = −0.19 e Å−3 |
186 parameters |
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. |
x | y | z | Uiso*/Ueq | ||
C1 | −0.2845 (2) | 0.22408 (8) | 0.34560 (7) | 0.0214 (3) | |
C2 | −0.4447 (2) | 0.29342 (9) | 0.35331 (8) | 0.0244 (3) | |
H2 | −0.4468 | 0.3487 | 0.3198 | 0.029* | |
C3 | −0.6002 (2) | 0.27850 (9) | 0.41161 (8) | 0.0286 (3) | |
H3 | −0.7127 | 0.3241 | 0.4176 | 0.034* | |
C4 | −0.5963 (2) | 0.19767 (10) | 0.46224 (8) | 0.0300 (3) | |
H4 | −0.7037 | 0.1901 | 0.5027 | 0.036* | |
C5 | −0.4385 (2) | 0.12915 (9) | 0.45400 (8) | 0.0269 (3) | |
H5 | −0.4370 | 0.0745 | 0.4883 | 0.032* | |
C6 | −0.2805 (2) | 0.14115 (8) | 0.39445 (8) | 0.0228 (3) | |
C7 | −0.1010 (2) | 0.08444 (8) | 0.36710 (7) | 0.0221 (3) | |
C8 | −0.0205 (2) | −0.00614 (9) | 0.38728 (8) | 0.0266 (3) | |
H8 | −0.0852 | −0.0427 | 0.4291 | 0.032* | |
C9 | 0.1525 (2) | −0.04017 (8) | 0.34536 (8) | 0.0278 (3) | |
H9 | 0.2088 | −0.1008 | 0.3590 | 0.033* | |
C10 | 0.2501 (2) | 0.01264 (8) | 0.28208 (8) | 0.0241 (3) | |
C11 | 0.1683 (2) | 0.10152 (8) | 0.25993 (7) | 0.0209 (3) | |
C12 | −0.0055 (2) | 0.13669 (8) | 0.30376 (7) | 0.0205 (2) | |
C13 | 0.4420 (2) | −0.02233 (9) | 0.24051 (9) | 0.0287 (3) | |
C14 | 0.5333 (2) | 0.04206 (10) | 0.17638 (9) | 0.0299 (3) | |
H14A | 0.5983 | 0.0041 | 0.1321 | 0.036* | |
H14B | 0.6559 | 0.0796 | 0.2058 | 0.036* | |
C15 | 0.3590 (2) | 0.10787 (9) | 0.13255 (8) | 0.0259 (3) | |
C16 | 0.1830 (2) | 0.05565 (10) | 0.07445 (8) | 0.0303 (3) | |
H16A | 0.1108 | 0.0086 | 0.1079 | 0.045* | |
H16B | 0.2552 | 0.0250 | 0.0283 | 0.045* | |
H16C | 0.0701 | 0.0998 | 0.0498 | 0.045* | |
C17 | 0.4667 (2) | 0.18495 (10) | 0.08453 (9) | 0.0338 (3) | |
H17A | 0.3501 | 0.2262 | 0.0578 | 0.051* | |
H17B | 0.5513 | 0.1576 | 0.0401 | 0.051* | |
H17C | 0.5685 | 0.2209 | 0.1245 | 0.051* | |
N1 | −0.11817 (17) | 0.21994 (7) | 0.29049 (6) | 0.0208 (2) | |
H1 | −0.073 (2) | 0.2679 (9) | 0.2619 (9) | 0.025* | |
O1 | 0.53069 (18) | −0.09781 (7) | 0.25866 (7) | 0.0406 (3) | |
O2 | 0.24499 (14) | 0.15638 (6) | 0.19818 (5) | 0.0237 (2) |
U11 | U22 | U33 | U12 | U13 | U23 | |
C1 | 0.0231 (6) | 0.0209 (6) | 0.0197 (6) | −0.0045 (5) | −0.0007 (5) | −0.0018 (5) |
C2 | 0.0267 (6) | 0.0219 (6) | 0.0243 (6) | −0.0012 (5) | 0.0006 (5) | −0.0017 (5) |
C3 | 0.0275 (7) | 0.0294 (7) | 0.0289 (7) | −0.0016 (5) | 0.0028 (5) | −0.0065 (5) |
C4 | 0.0294 (7) | 0.0357 (7) | 0.0258 (6) | −0.0094 (6) | 0.0066 (5) | −0.0050 (6) |
C5 | 0.0329 (7) | 0.0261 (6) | 0.0217 (6) | −0.0099 (5) | 0.0021 (5) | −0.0004 (5) |
C6 | 0.0264 (6) | 0.0212 (6) | 0.0200 (6) | −0.0058 (5) | −0.0023 (5) | −0.0015 (5) |
C7 | 0.0268 (6) | 0.0193 (6) | 0.0192 (6) | −0.0045 (5) | −0.0032 (5) | −0.0002 (4) |
C8 | 0.0372 (7) | 0.0196 (6) | 0.0216 (6) | −0.0049 (5) | −0.0042 (5) | 0.0026 (5) |
C9 | 0.0387 (7) | 0.0159 (6) | 0.0265 (6) | 0.0017 (5) | −0.0096 (6) | 0.0000 (5) |
C10 | 0.0279 (6) | 0.0185 (6) | 0.0241 (6) | 0.0011 (5) | −0.0075 (5) | −0.0046 (5) |
C11 | 0.0227 (6) | 0.0188 (6) | 0.0202 (6) | −0.0029 (5) | −0.0035 (5) | −0.0019 (4) |
C12 | 0.0236 (6) | 0.0164 (5) | 0.0205 (6) | −0.0021 (4) | −0.0031 (5) | −0.0006 (4) |
C13 | 0.0293 (7) | 0.0236 (6) | 0.0308 (7) | 0.0047 (5) | −0.0096 (5) | −0.0109 (5) |
C14 | 0.0236 (6) | 0.0352 (7) | 0.0302 (7) | 0.0051 (5) | −0.0017 (5) | −0.0112 (6) |
C15 | 0.0245 (6) | 0.0292 (7) | 0.0239 (6) | 0.0003 (5) | 0.0018 (5) | −0.0069 (5) |
C16 | 0.0306 (7) | 0.0344 (7) | 0.0247 (6) | −0.0013 (6) | −0.0041 (5) | −0.0047 (5) |
C17 | 0.0303 (7) | 0.0396 (8) | 0.0327 (7) | −0.0031 (6) | 0.0091 (6) | −0.0039 (6) |
N1 | 0.0240 (5) | 0.0160 (5) | 0.0226 (5) | −0.0007 (4) | 0.0032 (4) | 0.0024 (4) |
O1 | 0.0426 (6) | 0.0243 (5) | 0.0530 (7) | 0.0112 (4) | −0.0062 (5) | −0.0103 (5) |
O2 | 0.0258 (4) | 0.0218 (4) | 0.0239 (4) | −0.0001 (3) | 0.0048 (4) | −0.0019 (3) |
C1—N1 | 1.3790 (16) | C10—C13 | 1.4617 (18) |
C1—C2 | 1.3952 (17) | C11—O2 | 1.3599 (14) |
C1—C6 | 1.4135 (17) | C11—C12 | 1.3942 (17) |
C2—C3 | 1.3808 (18) | C12—N1 | 1.3775 (15) |
C2—H2 | 0.9500 | C13—O1 | 1.2275 (16) |
C3—C4 | 1.4039 (19) | C13—C14 | 1.505 (2) |
C3—H3 | 0.9500 | C14—C15 | 1.5239 (18) |
C4—C5 | 1.378 (2) | C14—H14A | 0.9900 |
C4—H4 | 0.9500 | C14—H14B | 0.9900 |
C5—C6 | 1.4005 (18) | C15—O2 | 1.4625 (15) |
C5—H5 | 0.9500 | C15—C17 | 1.5148 (19) |
C6—C7 | 1.4444 (18) | C15—C16 | 1.5252 (17) |
C7—C12 | 1.4071 (17) | C16—H16A | 0.9800 |
C7—C8 | 1.4111 (17) | C16—H16B | 0.9800 |
C8—C9 | 1.3679 (19) | C16—H16C | 0.9800 |
C8—H8 | 0.9500 | C17—H17A | 0.9800 |
C9—C10 | 1.4164 (19) | C17—H17B | 0.9800 |
C9—H9 | 0.9500 | C17—H17C | 0.9800 |
C10—C11 | 1.3976 (17) | N1—H1 | 0.878 (12) |
N1—C1—C2 | 128.89 (11) | N1—C12—C7 | 110.03 (11) |
N1—C1—C6 | 109.04 (11) | C11—C12—C7 | 121.75 (11) |
C2—C1—C6 | 121.99 (12) | O1—C13—C10 | 122.73 (13) |
C3—C2—C1 | 117.32 (12) | O1—C13—C14 | 121.29 (13) |
C3—C2—H2 | 121.3 | C10—C13—C14 | 115.92 (11) |
C1—C2—H2 | 121.3 | C13—C14—C15 | 113.88 (11) |
C2—C3—C4 | 121.68 (13) | C13—C14—H14A | 108.8 |
C2—C3—H3 | 119.2 | C15—C14—H14A | 108.8 |
C4—C3—H3 | 119.2 | C13—C14—H14B | 108.8 |
C5—C4—C3 | 120.76 (12) | C15—C14—H14B | 108.8 |
C5—C4—H4 | 119.6 | H14A—C14—H14B | 107.7 |
C3—C4—H4 | 119.6 | O2—C15—C17 | 104.54 (10) |
C4—C5—C6 | 119.14 (12) | O2—C15—C14 | 108.80 (10) |
C4—C5—H5 | 120.4 | C17—C15—C14 | 111.72 (11) |
C6—C5—H5 | 120.4 | O2—C15—C16 | 108.18 (10) |
C5—C6—C1 | 119.08 (12) | C17—C15—C16 | 111.33 (11) |
C5—C6—C7 | 134.14 (12) | C14—C15—C16 | 111.92 (11) |
C1—C6—C7 | 106.77 (11) | C15—C16—H16A | 109.5 |
C12—C7—C8 | 119.70 (12) | C15—C16—H16B | 109.5 |
C12—C7—C6 | 105.79 (10) | H16A—C16—H16B | 109.5 |
C8—C7—C6 | 134.42 (12) | C15—C16—H16C | 109.5 |
C9—C8—C7 | 118.63 (12) | H16A—C16—H16C | 109.5 |
C9—C8—H8 | 120.7 | H16B—C16—H16C | 109.5 |
C7—C8—H8 | 120.7 | C15—C17—H17A | 109.5 |
C8—C9—C10 | 121.73 (11) | C15—C17—H17B | 109.5 |
C8—C9—H9 | 119.1 | H17A—C17—H17B | 109.5 |
C10—C9—H9 | 119.1 | C15—C17—H17C | 109.5 |
C11—C10—C9 | 120.25 (12) | H17A—C17—H17C | 109.5 |
C11—C10—C13 | 118.29 (12) | H17B—C17—H17C | 109.5 |
C9—C10—C13 | 121.42 (11) | C12—N1—C1 | 108.36 (10) |
O2—C11—C12 | 117.29 (10) | C12—N1—H1 | 125.7 (9) |
O2—C11—C10 | 124.80 (11) | C1—N1—H1 | 124.3 (9) |
C12—C11—C10 | 117.90 (11) | C11—O2—C15 | 115.87 (10) |
N1—C12—C11 | 128.09 (11) | ||
N1—C1—C2—C3 | 177.14 (12) | C10—C11—C12—N1 | −176.92 (11) |
C6—C1—C2—C3 | 0.56 (18) | O2—C11—C12—C7 | 178.19 (10) |
C1—C2—C3—C4 | 0.94 (19) | C10—C11—C12—C7 | −1.42 (17) |
C2—C3—C4—C5 | −1.4 (2) | C8—C7—C12—N1 | 176.09 (10) |
C3—C4—C5—C6 | 0.24 (19) | C6—C7—C12—N1 | −1.00 (13) |
C4—C5—C6—C1 | 1.21 (18) | C8—C7—C12—C11 | −0.15 (18) |
C4—C5—C6—C7 | −177.49 (13) | C6—C7—C12—C11 | −177.24 (10) |
N1—C1—C6—C5 | −178.83 (11) | C11—C10—C13—O1 | 176.81 (12) |
C2—C1—C6—C5 | −1.65 (17) | C9—C10—C13—O1 | −1.12 (19) |
N1—C1—C6—C7 | 0.20 (13) | C11—C10—C13—C14 | −0.30 (16) |
C2—C1—C6—C7 | 177.38 (11) | C9—C10—C13—C14 | −178.23 (11) |
C5—C6—C7—C12 | 179.29 (13) | O1—C13—C14—C15 | 154.37 (12) |
C1—C6—C7—C12 | 0.48 (13) | C10—C13—C14—C15 | −28.47 (15) |
C5—C6—C7—C8 | 2.8 (2) | C13—C14—C15—O2 | 52.15 (14) |
C1—C6—C7—C8 | −175.98 (13) | C13—C14—C15—C17 | 167.05 (11) |
C12—C7—C8—C9 | 1.22 (17) | C13—C14—C15—C16 | −67.34 (14) |
C6—C7—C8—C9 | 177.30 (13) | C11—C12—N1—C1 | 177.08 (11) |
C7—C8—C9—C10 | −0.71 (18) | C7—C12—N1—C1 | 1.15 (13) |
C8—C9—C10—C11 | −0.88 (18) | C2—C1—N1—C12 | −177.75 (12) |
C8—C9—C10—C13 | 177.01 (11) | C6—C1—N1—C12 | −0.82 (13) |
C9—C10—C11—O2 | −177.66 (11) | C12—C11—O2—C15 | −157.25 (10) |
C13—C10—C11—O2 | 4.38 (17) | C10—C11—O2—C15 | 22.33 (16) |
C9—C10—C11—C12 | 1.92 (17) | C17—C15—O2—C11 | −168.60 (10) |
C13—C10—C11—C12 | −176.04 (10) | C14—C15—O2—C11 | −49.13 (13) |
O2—C11—C12—N1 | 2.69 (18) | C16—C15—O2—C11 | 72.67 (13) |
D—H···A | D—H | H···A | D···A | D—H···A |
N1—H1···O1i | 0.88 (1) | 1.97 (1) | 2.7876 (14) | 154 (1) |
C14—H14B···Cg1ii | 0.99 | 2.58 | 3.4754 (15) | 151 |
Symmetry codes: (i) −x+1/2, y+1/2, −z+1/2; (ii) x+1, y, z. |
Experimental details
Crystal data | |
Chemical formula | C17H15NO2 |
Mr | 265.30 |
Crystal system, space group | Monoclinic, P21/n |
Temperature (K) | 100 |
a, b, c (Å) | 5.9926 (5), 14.3368 (12), 15.6839 (13) |
β (°) | 95.270 (1) |
V (Å3) | 1341.78 (19) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 0.09 |
Crystal size (mm) | 0.37 × 0.19 × 0.16 |
Data collection | |
Diffractometer | Bruker APEX CCD diffractometer |
Absorption correction | Multi-scan (SADABS; Bruker, 2007) |
Tmin, Tmax | 0.887, 0.986 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 12548, 3083, 2630 |
Rint | 0.026 |
(sin θ/λ)max (Å−1) | 0.649 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.041, 0.094, 1.06 |
No. of reflections | 3083 |
No. of parameters | 186 |
No. of restraints | 1 |
H-atom treatment | H atoms treated by a mixture of independent and constrained refinement |
Δρmax, Δρmin (e Å−3) | 0.20, −0.19 |
Computer programs: APEX2 (Bruker, 2007), SAINT (Bruker, 2007), SHELXTL (Version 6.14; Sheldrick, 2008), Mercury (Version 2.0; Macrae et al., 2006).
D—H···A | D—H | H···A | D···A | D—H···A |
N1—H1···O1i | 0.878 (12) | 1.973 (13) | 2.7876 (14) | 153.9 (13) |
C14—H14B···Cg1ii | 0.99 | 2.58 | 3.4754 (15) | 151 |
Symmetry codes: (i) −x+1/2, y+1/2, −z+1/2; (ii) x+1, y, z. |
Pyranocarbazoles such as grinimbine, mupamine, mahanimbine, murrayanol and mahanine have been isolated from plant species of the Rutaceae family (Knölker & Reddy, 2002, and references therein) and these alkaloids possess mosquitocidal, antimicrobial, anti-inflammatory and antioxidant activities (Shanazarov et al., 1989). In general pyranocarbazole alkaloids have a C-13, C-18 or C-23 framework with a C-12 carbazole nucleus as the basic unit in which one carbon is attached as a methyl, formyl, carboxylic or ester group. Another observation is that in many of the pyranocarbazole derivatives isolated so far, the oxygen atom of the pyran ring is attached to carbon atom 2 of the carbazole nucleus to form pyrano[3,2-a]carbazoles as in grinimbine. Of the 10 simple carbazole alkaloids isolated so far, five have the oxygen function on carbon 1 (or its equivalent position C 8). The C-18 pyrano[3,2-a] alkaloid mupamine posseses a methoxy group at position 8, hence there exists a substrate on which a pyrano[2,3-a]carbazole could be built upon in the plant body; however, none of the pyranocarbazoles isolated so far has a pyran ring with oxygen on carbon 1 or its equivalent position C 8.
In this context we aimed to prepare pyrano[2,3-a]carbazoles using 1-hydroxycarbazoles as starting synthons under various reaction conditions (Kavitha & Prasad, 2003, and references therein). Using the catalyst mixture AlCl3/POCl3 along with 1-hydroxycarbazole and 3,3-dimethyacrylic acid as the reactants we were able to generate a mixture of two products i.e., 2-(3,3-dimethylacryloyl)-1-hydroxycarbazole (2) and the title compound 2,2-dimethyl-2,3-dihydropyrano-[2,3-a]carbazol-4(11H)-one (3) (Figure 1).
The single-crystal structure confirmed the formation of the dihydropyrano-[2,3-a]carbazol-4(11H)-one framework as shown in Figure 2. Data collection and structure refinement were unproblematic and all structural parameters (bond lengths, angles, etc) are in the expected ranges. The molecules crystallize in a monoclinic setting in P21/n with four largely planar molecules per unit cell. The plane defined by the sp2 hybridized carbon atoms, the CH2 group and the N and O atoms has an r.m.s. deviation from planarity of only 0.036 Å. Of all the ring C atoms only C15 of the pyran C(Me)2 unit is significately out of plane with the atoms of the four fused rings, its deviation being 0.611 (1) Å. The pyran ring thus exhibits a half chair conformation.
One of the methyl groups of the C(Me)2 unit is also located close to the average plane of the molecule (C17 with a deviation of 0.264 (1) Å). The other, C16, is however located 2.121 (1) Å away from this plane and thus makes the molecule as a whole not planar and prevents it form forming extensive π-π stacked entities in the solid state. The packing is thus indeed dominated by strong N—H···O hydrogen bonds (Table 1) and a weaker C—H···C (Table 1) interaction. The unusual C—H···C bond could also be described as a C—H···π interaction [C14—H14b···Cg1iii = 2.58 Å with Cg1 being the centroid of the C1/C6/C7/C12/N1 pyrrole ring and iii = 1 + x, y, z)]. The only noticeable π···π stacking interaction observed is a slipped one between Cg3 and Cg4iv with a centroid to centroid distance of 3.8425 (8) Å (Cg3 and Cg4 are C1 to C6 and C7 to C12, respectively, iv = -1 + x, y, z).
The N—H···O hydrogen bonds that dominate the packing of the title compound tie molecules together to infinite chains that extend along the crystallographic b axis as shown in Figure 3.
The structures of the 9- and 10-methyl derivatives of (I) are described in Sridharan, Rajendra Prasad & Zeller (2008) and Sridharan, Rajendra Prasad, Ngendahimana et al. (2008). For a more detailed comparison of structures and packing of these three compounds, see Sridharan, Rajendra Prasad & Zeller (2008).