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Acta Crystallogr Sect E Struct Rep Online. 2008 November 1; 64(Pt 11): o2155.
Published online 2008 October 22. doi:  10.1107/S1600536808033849
PMCID: PMC2959512

2,2-Dimethyl-2,3-dihydro­pyrano[2,3-a]carbazol-4(11H)-one

Abstract

The title compound, C17H15NO2, was prepared from 1-hydroxy­carbazole and 3,3-dimethyl­acrylic acid with a mixture of AlCl3 and POCl3 as the cyclization catalyst. Owing to the presence of the –CMe2– group, the mol­ecule is not quite planar. In the crystal structre, strong N—H(...)O hydrogen bonds and weaker C—H(...)π inter­actions occur, and a slipped π–π stacking inter­action [centroid–centroid separation = 3.8425 (8) Å] is also observed.

Related literature

Knölker & Reddy (2002 [triangle]) report on the isolation of pyran­ocarbazoles from various plant species, and Shanaza­rov et al. (1989 [triangle]) on their potential beneficial properties. Kavitha & Prasad (2003 [triangle]) describe the synthesis of compounds related to the title compound. Sridharan, Rajendra Prasad & Zeller (2008 [triangle]) report the structure of the 9-methyl derivative of the title compound. Sridharan, Rajendra Prasad, Ngendahimana & Zeller (2008 [triangle]) report the structure of the 10-methyl derivative of the title compound.

An external file that holds a picture, illustration, etc.
Object name is e-64-o2155-scheme1.jpg

Experimental

Crystal data

  • C17H15NO2
  • M r = 265.30
  • Monoclinic, An external file that holds a picture, illustration, etc.
Object name is e-64-o2155-efi1.jpg
  • a = 5.9926 (5) Å
  • b = 14.3368 (12) Å
  • c = 15.6839 (13) Å
  • β = 95.270 (1)°
  • V = 1341.78 (19) Å3
  • Z = 4
  • Mo Kα radiation
  • μ = 0.09 mm−1
  • T = 100 (2) K
  • 0.37 × 0.19 × 0.16 mm

Data collection

  • Bruker SMART APEX CCD diffractometer
  • Absorption correction: multi-scan (SADABS; Bruker, 2007 [triangle]) T min = 0.887, T max = 0.986
  • 12548 measured reflections
  • 3083 independent reflections
  • 2630 reflections with I > 2σ(I)
  • R int = 0.026

Refinement

  • R[F 2 > 2σ(F 2)] = 0.041
  • wR(F 2) = 0.094
  • S = 1.06
  • 3083 reflections
  • 186 parameters
  • 1 restraint
  • H atoms treated by a mixture of independent and constrained refinement
  • Δρmax = 0.20 e Å−3
  • Δρmin = −0.19 e Å−3

Data collection: APEX2 (Bruker, 2007 [triangle]); cell refinement: SAINT (Bruker, 2007 [triangle]); data reduction: SAINT; program(s) used to solve structure: SHELXTL (Sheldrick, 2008 [triangle]); program(s) used to refine structure: SHELXTL; molecular graphics: Mercury (Macrae et al., 2006 [triangle]); software used to prepare material for publication: SHELXTL.

Table 1
Hydrogen-bond geometry (Å, °)

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536808033849/hb2803sup1.cif

Structure factors: contains datablocks I. DOI: 10.1107/S1600536808033849/hb2803Isup2.hkl

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Acknowledgments

We acknowledge UGC, New Delhi, India, for the award of Major Research Project grant No. F. 31-122/2005. MS thanks UGC, New Delhi, for the award of a research fellowship. The diffractometer was funded by NSF grant No. 0087210, by Ohio Board of Regents grant CAP-491 and by YSU.

supplementary crystallographic information

Comment

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).

Experimental

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.

Refinement

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).

Figures

Fig. 1.
Reaction sequence
Fig. 2.
The molecular structure of (I) displaying xx% displacement ellipsoids. H atoms are represented in stick mode.
Fig. 3.
Packing view of (I) down the a axis showing chains built by the N—H···O hydrogen bonds (indicated by blue dashed lines).

Crystal data

C17H15NO2F(000) = 560
Mr = 265.30Dx = 1.313 Mg m3
Monoclinic, P21/nMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ynCell parameters from 4649 reflections
a = 5.9926 (5) Åθ = 2.6–27.5°
b = 14.3368 (12) ŵ = 0.09 mm1
c = 15.6839 (13) ÅT = 100 K
β = 95.270 (1)°Plate, yellow
V = 1341.78 (19) Å30.37 × 0.19 × 0.16 mm
Z = 4

Data collection

Bruker APEX CCD diffractometer3083 independent reflections
Radiation source: fine-focus sealed tube2630 reflections with I > 2σ(I)
graphiteRint = 0.026
ω scansθmax = 27.5°, θmin = 1.9°
Absorption correction: multi-scan (SADABS; Bruker, 2007)h = −7→7
Tmin = 0.887, Tmax = 0.986k = −18→18
12548 measured reflectionsl = −20→20

Refinement

Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.041Hydrogen site location: difmap and geom
wR(F2) = 0.094H atoms treated by a mixture of independent and constrained refinement
S = 1.06w = 1/[σ2(Fo2) + (0.035P)2 + 0.4678P] where P = (Fo2 + 2Fc2)/3
3083 reflections(Δ/σ)max < 0.001
186 parametersΔρmax = 0.20 e Å3
1 restraintΔρmin = −0.19 e Å3

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 (Å2)

xyzUiso*/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)
H2−0.44680.34870.31980.029*
C3−0.6002 (2)0.27850 (9)0.41161 (8)0.0286 (3)
H3−0.71270.32410.41760.034*
C4−0.5963 (2)0.19767 (10)0.46224 (8)0.0300 (3)
H4−0.70370.19010.50270.036*
C5−0.4385 (2)0.12915 (9)0.45400 (8)0.0269 (3)
H5−0.43700.07450.48830.032*
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)
H8−0.0852−0.04270.42910.032*
C90.1525 (2)−0.04017 (8)0.34536 (8)0.0278 (3)
H90.2088−0.10080.35900.033*
C100.2501 (2)0.01264 (8)0.28208 (8)0.0241 (3)
C110.1683 (2)0.10152 (8)0.25993 (7)0.0209 (3)
C12−0.0055 (2)0.13669 (8)0.30376 (7)0.0205 (2)
C130.4420 (2)−0.02233 (9)0.24051 (9)0.0287 (3)
C140.5333 (2)0.04206 (10)0.17638 (9)0.0299 (3)
H14A0.59830.00410.13210.036*
H14B0.65590.07960.20580.036*
C150.3590 (2)0.10787 (9)0.13255 (8)0.0259 (3)
C160.1830 (2)0.05565 (10)0.07445 (8)0.0303 (3)
H16A0.11080.00860.10790.045*
H16B0.25520.02500.02830.045*
H16C0.07010.09980.04980.045*
C170.4667 (2)0.18495 (10)0.08453 (9)0.0338 (3)
H17A0.35010.22620.05780.051*
H17B0.55130.15760.04010.051*
H17C0.56850.22090.12450.051*
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*
O10.53069 (18)−0.09781 (7)0.25866 (7)0.0406 (3)
O20.24499 (14)0.15638 (6)0.19818 (5)0.0237 (2)

Atomic displacement parameters (Å2)

U11U22U33U12U13U23
C10.0231 (6)0.0209 (6)0.0197 (6)−0.0045 (5)−0.0007 (5)−0.0018 (5)
C20.0267 (6)0.0219 (6)0.0243 (6)−0.0012 (5)0.0006 (5)−0.0017 (5)
C30.0275 (7)0.0294 (7)0.0289 (7)−0.0016 (5)0.0028 (5)−0.0065 (5)
C40.0294 (7)0.0357 (7)0.0258 (6)−0.0094 (6)0.0066 (5)−0.0050 (6)
C50.0329 (7)0.0261 (6)0.0217 (6)−0.0099 (5)0.0021 (5)−0.0004 (5)
C60.0264 (6)0.0212 (6)0.0200 (6)−0.0058 (5)−0.0023 (5)−0.0015 (5)
C70.0268 (6)0.0193 (6)0.0192 (6)−0.0045 (5)−0.0032 (5)−0.0002 (4)
C80.0372 (7)0.0196 (6)0.0216 (6)−0.0049 (5)−0.0042 (5)0.0026 (5)
C90.0387 (7)0.0159 (6)0.0265 (6)0.0017 (5)−0.0096 (6)0.0000 (5)
C100.0279 (6)0.0185 (6)0.0241 (6)0.0011 (5)−0.0075 (5)−0.0046 (5)
C110.0227 (6)0.0188 (6)0.0202 (6)−0.0029 (5)−0.0035 (5)−0.0019 (4)
C120.0236 (6)0.0164 (5)0.0205 (6)−0.0021 (4)−0.0031 (5)−0.0006 (4)
C130.0293 (7)0.0236 (6)0.0308 (7)0.0047 (5)−0.0096 (5)−0.0109 (5)
C140.0236 (6)0.0352 (7)0.0302 (7)0.0051 (5)−0.0017 (5)−0.0112 (6)
C150.0245 (6)0.0292 (7)0.0239 (6)0.0003 (5)0.0018 (5)−0.0069 (5)
C160.0306 (7)0.0344 (7)0.0247 (6)−0.0013 (6)−0.0041 (5)−0.0047 (5)
C170.0303 (7)0.0396 (8)0.0327 (7)−0.0031 (6)0.0091 (6)−0.0039 (6)
N10.0240 (5)0.0160 (5)0.0226 (5)−0.0007 (4)0.0032 (4)0.0024 (4)
O10.0426 (6)0.0243 (5)0.0530 (7)0.0112 (4)−0.0062 (5)−0.0103 (5)
O20.0258 (4)0.0218 (4)0.0239 (4)−0.0001 (3)0.0048 (4)−0.0019 (3)

Geometric parameters (Å, °)

C1—N11.3790 (16)C10—C131.4617 (18)
C1—C21.3952 (17)C11—O21.3599 (14)
C1—C61.4135 (17)C11—C121.3942 (17)
C2—C31.3808 (18)C12—N11.3775 (15)
C2—H20.9500C13—O11.2275 (16)
C3—C41.4039 (19)C13—C141.505 (2)
C3—H30.9500C14—C151.5239 (18)
C4—C51.378 (2)C14—H14A0.9900
C4—H40.9500C14—H14B0.9900
C5—C61.4005 (18)C15—O21.4625 (15)
C5—H50.9500C15—C171.5148 (19)
C6—C71.4444 (18)C15—C161.5252 (17)
C7—C121.4071 (17)C16—H16A0.9800
C7—C81.4111 (17)C16—H16B0.9800
C8—C91.3679 (19)C16—H16C0.9800
C8—H80.9500C17—H17A0.9800
C9—C101.4164 (19)C17—H17B0.9800
C9—H90.9500C17—H17C0.9800
C10—C111.3976 (17)N1—H10.878 (12)
N1—C1—C2128.89 (11)N1—C12—C7110.03 (11)
N1—C1—C6109.04 (11)C11—C12—C7121.75 (11)
C2—C1—C6121.99 (12)O1—C13—C10122.73 (13)
C3—C2—C1117.32 (12)O1—C13—C14121.29 (13)
C3—C2—H2121.3C10—C13—C14115.92 (11)
C1—C2—H2121.3C13—C14—C15113.88 (11)
C2—C3—C4121.68 (13)C13—C14—H14A108.8
C2—C3—H3119.2C15—C14—H14A108.8
C4—C3—H3119.2C13—C14—H14B108.8
C5—C4—C3120.76 (12)C15—C14—H14B108.8
C5—C4—H4119.6H14A—C14—H14B107.7
C3—C4—H4119.6O2—C15—C17104.54 (10)
C4—C5—C6119.14 (12)O2—C15—C14108.80 (10)
C4—C5—H5120.4C17—C15—C14111.72 (11)
C6—C5—H5120.4O2—C15—C16108.18 (10)
C5—C6—C1119.08 (12)C17—C15—C16111.33 (11)
C5—C6—C7134.14 (12)C14—C15—C16111.92 (11)
C1—C6—C7106.77 (11)C15—C16—H16A109.5
C12—C7—C8119.70 (12)C15—C16—H16B109.5
C12—C7—C6105.79 (10)H16A—C16—H16B109.5
C8—C7—C6134.42 (12)C15—C16—H16C109.5
C9—C8—C7118.63 (12)H16A—C16—H16C109.5
C9—C8—H8120.7H16B—C16—H16C109.5
C7—C8—H8120.7C15—C17—H17A109.5
C8—C9—C10121.73 (11)C15—C17—H17B109.5
C8—C9—H9119.1H17A—C17—H17B109.5
C10—C9—H9119.1C15—C17—H17C109.5
C11—C10—C9120.25 (12)H17A—C17—H17C109.5
C11—C10—C13118.29 (12)H17B—C17—H17C109.5
C9—C10—C13121.42 (11)C12—N1—C1108.36 (10)
O2—C11—C12117.29 (10)C12—N1—H1125.7 (9)
O2—C11—C10124.80 (11)C1—N1—H1124.3 (9)
C12—C11—C10117.90 (11)C11—O2—C15115.87 (10)
N1—C12—C11128.09 (11)
N1—C1—C2—C3177.14 (12)C10—C11—C12—N1−176.92 (11)
C6—C1—C2—C30.56 (18)O2—C11—C12—C7178.19 (10)
C1—C2—C3—C40.94 (19)C10—C11—C12—C7−1.42 (17)
C2—C3—C4—C5−1.4 (2)C8—C7—C12—N1176.09 (10)
C3—C4—C5—C60.24 (19)C6—C7—C12—N1−1.00 (13)
C4—C5—C6—C11.21 (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—O1176.81 (12)
C2—C1—C6—C5−1.65 (17)C9—C10—C13—O1−1.12 (19)
N1—C1—C6—C70.20 (13)C11—C10—C13—C14−0.30 (16)
C2—C1—C6—C7177.38 (11)C9—C10—C13—C14−178.23 (11)
C5—C6—C7—C12179.29 (13)O1—C13—C14—C15154.37 (12)
C1—C6—C7—C120.48 (13)C10—C13—C14—C15−28.47 (15)
C5—C6—C7—C82.8 (2)C13—C14—C15—O252.15 (14)
C1—C6—C7—C8−175.98 (13)C13—C14—C15—C17167.05 (11)
C12—C7—C8—C91.22 (17)C13—C14—C15—C16−67.34 (14)
C6—C7—C8—C9177.30 (13)C11—C12—N1—C1177.08 (11)
C7—C8—C9—C10−0.71 (18)C7—C12—N1—C11.15 (13)
C8—C9—C10—C11−0.88 (18)C2—C1—N1—C12−177.75 (12)
C8—C9—C10—C13177.01 (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—O24.38 (17)C10—C11—O2—C1522.33 (16)
C9—C10—C11—C121.92 (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—N12.69 (18)C16—C15—O2—C1172.67 (13)

Hydrogen-bond geometry (Å, °)

D—H···AD—HH···AD···AD—H···A
N1—H1···O1i0.88 (1)1.97 (1)2.7876 (14)154 (1)
C14—H14B···Cg1ii0.992.583.4754 (15)151

Symmetry codes: (i) −x+1/2, y+1/2, −z+1/2; (ii) x+1, y, z.

Footnotes

Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: HB2803).

References

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