Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536807050015/bi2241sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S1600536807050015/bi2241Isup2.hkl |
CCDC reference: 667377
Key indicators
- Single-crystal X-ray study
- T = 298 K
- R factor = 0.055
- wR factor = 0.150
- Data-to-parameter ratio = 19.0
checkCIF/PLATON results
No syntax errors found No errors found in this datablock
A low-yield synthesis of the title compound has been reported previously by Patel (1982). The use of trifluoroacetic acid as an acylating agent is descibed in Rajendra Prasad & Vijayalakshmi (1994); Sowmithran & Rajendra Prasad (1986).
6-Methyl-1-hydroxy carbazole (0.001 mol) dissolved in 10 ml of trifluoroacetic acid was heated with 3,3-dimethylacrylic acid (0.001 mol) at 323 K for 5 h. After completion of the reaction (as monitored by TLC), the excess trifluroacetic acid was removed using rotary evaporation. A solid precipitated out and the residue was poured onto ice water, then extracted using ethyl acetate and washed with water. The combined organic layers were dried over anhydrous sodium sulfate and filtered, then the solvent was removed under vacuum and the residue was purified by column chromatography on silica gel using petroleum ether / ethyl acetate (95:5) as eluant. Evaporation of the solvent afforded yellow crystals which were recrystallized from ethanol to yield the title compound in 91% yield (m.p. 489–491 K).
H atoms were added in calculated positions with C—H = 0.96 or 0.97 Å, N—H = 0.86 Å, and refined using a riding model with Uiso(H) = 1.2Ueq(C/N).
A low-yield synthesis of the title compound has been reported previously by Patel (1982). Using trifluoroacetic acid as the acylating agent (Rajendra Prasad & Vijayalakshmi (1994); Sowmithran & Rajendra Prasad (1986)), we have prepared the compound in excellent yield as the sole product of a one-step synthesis (Fig. 1). Crystallization from ethanol yielded crystals suitable for X-ray diffraction analysis. In the crystal, the molecule is essentially planar (Fig. 2), with only atom C15 and the adjacent two methyl groups (C16, C17) of the 2,2-dimethyl-2H-pyran-4(3H)-one unit deviating significantly from the mean plane of the other atoms. The RMS deviation for all non-H atoms excluding C15, C16 and C17 is 0.045 Å and the deviation from the plane is -0.590 (2), 2.102 (2) and -0.221 (2) Å for C15, C16 and C17, respectively.
Intermolecular N—H···O hydrogen bonds are formed, with the keto oxygen atom O2 acting as the acceptor, and C—H···π contacts are observed between C14 and the π system of the pyrrole ring, with a C—H···Cgii distance of 2.58 Å (symmetry code: (ii) 1 + x, y, z). The other face of the pyrrole ring accepts another significantly longer C—H···π contact from the methyl group C18, with a C—H···Cgiii distance of 3.00 Å (symmetry code (iii): -1 + x, y, z). While the flat molecules are in part parallel to each other, no strong π..π stacking interactions are observed.
The N—H···O hydrogen bonds connect individual molecules into infinite chains along the b-axis. The two types of C—H···π contacts are formed between molecules adjacent along the a-axis. Both types of highlighted interactions are formed between molecules lying within layers parallel to the (001) planes, and the c-axis spans two such layers (Fig. 3).
A low-yield synthesis of the title compound has been reported previously by Patel (1982). The use of trifluoroacetic acid as an acylating agent is descibed in Rajendra Prasad & Vijayalakshmi (1994); Sowmithran & Rajendra Prasad (1986).
Data collection: SMART (Bruker, 2003); cell refinement: SAINT-Plus (Bruker, 2003); data reduction: SAINT-Plus (Bruker, 2003); program(s) used to solve structure: SHELXTL (Bruker, 2003); program(s) used to refine structure: SHELXTL (Bruker, 2003); molecular graphics: SHELXTL (Bruker, 2003); software used to prepare material for publication: SHELXTL (Bruker, 2003).
C18H17NO2 | F(000) = 592 |
Mr = 279.33 | Dx = 1.245 Mg m−3 |
Monoclinic, P21/n | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -P 2yn | Cell parameters from 5575 reflections |
a = 6.7323 (3) Å | θ = 2.6–30.5° |
b = 14.3303 (7) Å | µ = 0.08 mm−1 |
c = 15.6502 (8) Å | T = 298 K |
β = 99.152 (1)° | Plate, yellow |
V = 1490.65 (12) Å3 | 0.47 × 0.43 × 0.17 mm |
Z = 4 |
Bruker SMART APEX CCD diffractometer | 3676 independent reflections |
Radiation source: fine-focus sealed tube | 2866 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.027 |
ω scans | θmax = 28.3°, θmin = 1.9° |
Absorption correction: multi-scan (SADABS; Bruker, 2007) | h = −8→8 |
Tmin = 0.906, Tmax = 0.986 | k = −18→19 |
11129 measured reflections | l = −20→16 |
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)] = 0.055 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.150 | H-atom parameters constrained |
S = 1.06 | w = 1/[σ2(Fo2) + (0.0715P)2 + 0.208P] where P = (Fo2 + 2Fc2)/3 |
3676 reflections | (Δ/σ)max = 0.001 |
193 parameters | Δρmax = 0.20 e Å−3 |
0 restraints | Δρmin = −0.20 e Å−3 |
C18H17NO2 | V = 1490.65 (12) Å3 |
Mr = 279.33 | Z = 4 |
Monoclinic, P21/n | Mo Kα radiation |
a = 6.7323 (3) Å | µ = 0.08 mm−1 |
b = 14.3303 (7) Å | T = 298 K |
c = 15.6502 (8) Å | 0.47 × 0.43 × 0.17 mm |
β = 99.152 (1)° |
Bruker SMART APEX CCD diffractometer | 3676 independent reflections |
Absorption correction: multi-scan (SADABS; Bruker, 2007) | 2866 reflections with I > 2σ(I) |
Tmin = 0.906, Tmax = 0.986 | Rint = 0.027 |
11129 measured reflections |
R[F2 > 2σ(F2)] = 0.055 | 0 restraints |
wR(F2) = 0.150 | H-atom parameters constrained |
S = 1.06 | Δρmax = 0.20 e Å−3 |
3676 reflections | Δρmin = −0.20 e Å−3 |
193 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 | −0.2265 (2) | 0.28205 (10) | 0.33056 (10) | 0.0548 (4) | |
C2 | −0.3687 (3) | 0.21301 (11) | 0.33728 (12) | 0.0634 (4) | |
H2 | −0.3726 | 0.1582 | 0.3052 | 0.076* | |
C3 | −0.5030 (3) | 0.22888 (12) | 0.39311 (12) | 0.0668 (4) | |
H3 | −0.5999 | 0.1837 | 0.3978 | 0.080* | |
C4 | −0.5010 (2) | 0.31017 (12) | 0.44367 (11) | 0.0629 (4) | |
C5 | −0.3611 (2) | 0.37843 (11) | 0.43512 (10) | 0.0584 (4) | |
H5 | −0.3591 | 0.4332 | 0.4671 | 0.070* | |
C6 | −0.2224 (2) | 0.36555 (10) | 0.37862 (10) | 0.0526 (3) | |
C7 | −0.0635 (2) | 0.42209 (10) | 0.35340 (10) | 0.0516 (3) | |
C8 | 0.0111 (3) | 0.51209 (10) | 0.37606 (11) | 0.0588 (4) | |
H8 | −0.0448 | 0.5482 | 0.4155 | 0.071* | |
C9 | 0.1672 (3) | 0.54513 (10) | 0.33884 (11) | 0.0598 (4) | |
H9 | 0.2182 | 0.6042 | 0.3540 | 0.072* | |
C10 | 0.2537 (2) | 0.49222 (10) | 0.27784 (10) | 0.0529 (4) | |
C11 | 0.1767 (2) | 0.40375 (9) | 0.25316 (9) | 0.0493 (3) | |
C12 | 0.0202 (2) | 0.36987 (9) | 0.29234 (9) | 0.0507 (3) | |
C13 | 0.4290 (2) | 0.52526 (10) | 0.24281 (11) | 0.0586 (4) | |
C14 | 0.5098 (2) | 0.46048 (12) | 0.18106 (11) | 0.0624 (4) | |
H14A | 0.6162 | 0.4230 | 0.2133 | 0.075* | |
H14B | 0.5690 | 0.4975 | 0.1397 | 0.075* | |
C15 | 0.3540 (2) | 0.39582 (11) | 0.13186 (10) | 0.0572 (4) | |
C16 | 0.1999 (3) | 0.44889 (14) | 0.06790 (12) | 0.0786 (5) | |
H16A | 0.1010 | 0.4061 | 0.0397 | 0.118* | |
H16B | 0.2665 | 0.4788 | 0.0254 | 0.118* | |
H16C | 0.1353 | 0.4951 | 0.0983 | 0.118* | |
C17 | 0.4503 (3) | 0.31758 (13) | 0.08771 (13) | 0.0752 (5) | |
H17A | 0.5383 | 0.2825 | 0.1302 | 0.113* | |
H17B | 0.5262 | 0.3435 | 0.0464 | 0.113* | |
H17C | 0.3474 | 0.2773 | 0.0585 | 0.113* | |
C18 | −0.6477 (3) | 0.32132 (15) | 0.50596 (15) | 0.0853 (6) | |
H18A | −0.6206 | 0.2752 | 0.5508 | 0.128* | |
H18B | −0.7823 | 0.3133 | 0.4757 | 0.128* | |
H18C | −0.6340 | 0.3825 | 0.5312 | 0.128* | |
N1 | −0.0805 (2) | 0.28588 (8) | 0.27825 (9) | 0.0576 (3) | |
H1 | −0.0560 | 0.2432 | 0.2428 | 0.069* | |
O1 | 0.24620 (16) | 0.34866 (7) | 0.19360 (7) | 0.0575 (3) | |
O2 | 0.5125 (2) | 0.59946 (8) | 0.26454 (10) | 0.0843 (4) |
U11 | U22 | U33 | U12 | U13 | U23 | |
C1 | 0.0618 (8) | 0.0458 (7) | 0.0563 (8) | 0.0020 (6) | 0.0083 (7) | 0.0034 (6) |
C2 | 0.0711 (10) | 0.0477 (8) | 0.0707 (10) | −0.0062 (7) | 0.0087 (8) | 0.0035 (7) |
C3 | 0.0645 (9) | 0.0586 (9) | 0.0762 (11) | −0.0068 (7) | 0.0081 (8) | 0.0147 (8) |
C4 | 0.0586 (9) | 0.0653 (9) | 0.0652 (10) | 0.0051 (7) | 0.0107 (7) | 0.0141 (8) |
C5 | 0.0636 (9) | 0.0545 (8) | 0.0574 (9) | 0.0066 (7) | 0.0109 (7) | 0.0028 (7) |
C6 | 0.0583 (8) | 0.0455 (7) | 0.0530 (8) | 0.0029 (6) | 0.0054 (6) | 0.0024 (6) |
C7 | 0.0578 (8) | 0.0451 (7) | 0.0514 (8) | 0.0021 (6) | 0.0070 (6) | −0.0006 (6) |
C8 | 0.0713 (9) | 0.0454 (7) | 0.0608 (9) | 0.0019 (7) | 0.0139 (7) | −0.0093 (7) |
C9 | 0.0726 (10) | 0.0404 (7) | 0.0656 (10) | −0.0044 (6) | 0.0088 (8) | −0.0068 (6) |
C10 | 0.0609 (8) | 0.0419 (7) | 0.0549 (8) | 0.0009 (6) | 0.0062 (7) | 0.0029 (6) |
C11 | 0.0567 (8) | 0.0410 (7) | 0.0495 (8) | 0.0053 (5) | 0.0062 (6) | 0.0007 (5) |
C12 | 0.0585 (8) | 0.0395 (7) | 0.0532 (8) | 0.0019 (6) | 0.0059 (6) | −0.0004 (6) |
C13 | 0.0664 (9) | 0.0450 (7) | 0.0635 (9) | −0.0008 (6) | 0.0076 (7) | 0.0111 (7) |
C14 | 0.0604 (9) | 0.0648 (9) | 0.0630 (10) | 0.0008 (7) | 0.0126 (7) | 0.0067 (7) |
C15 | 0.0622 (9) | 0.0571 (8) | 0.0527 (8) | 0.0067 (7) | 0.0109 (7) | 0.0043 (7) |
C16 | 0.0902 (13) | 0.0816 (12) | 0.0591 (10) | 0.0178 (10) | −0.0030 (9) | 0.0066 (9) |
C17 | 0.0800 (12) | 0.0753 (11) | 0.0736 (12) | 0.0118 (9) | 0.0231 (10) | −0.0075 (9) |
C18 | 0.0736 (12) | 0.0920 (14) | 0.0956 (15) | 0.0030 (10) | 0.0295 (11) | 0.0134 (11) |
N1 | 0.0692 (8) | 0.0410 (6) | 0.0644 (8) | −0.0036 (5) | 0.0167 (6) | −0.0077 (5) |
O1 | 0.0684 (6) | 0.0458 (5) | 0.0607 (6) | 0.0031 (5) | 0.0174 (5) | −0.0034 (4) |
O2 | 0.0984 (10) | 0.0509 (6) | 0.1084 (11) | −0.0191 (6) | 0.0310 (8) | −0.0011 (6) |
C1—N1 | 1.377 (2) | C11—C12 | 1.388 (2) |
C1—C2 | 1.392 (2) | C12—N1 | 1.3816 (18) |
C1—C6 | 1.411 (2) | C13—O2 | 1.2254 (19) |
C2—C3 | 1.372 (3) | C13—C14 | 1.503 (2) |
C2—H2 | 0.930 | C14—C15 | 1.515 (2) |
C3—C4 | 1.407 (3) | C14—H14A | 0.970 |
C3—H3 | 0.930 | C14—H14B | 0.970 |
C4—C5 | 1.379 (2) | C15—O1 | 1.4628 (19) |
C4—C18 | 1.502 (3) | C15—C17 | 1.516 (2) |
C5—C6 | 1.397 (2) | C15—C16 | 1.525 (2) |
C5—H5 | 0.930 | C16—H16A | 0.960 |
C6—C7 | 1.446 (2) | C16—H16B | 0.960 |
C7—C12 | 1.401 (2) | C16—H16C | 0.960 |
C7—C8 | 1.409 (2) | C17—H17A | 0.960 |
C8—C9 | 1.364 (2) | C17—H17B | 0.960 |
C8—H8 | 0.930 | C17—H17C | 0.960 |
C9—C10 | 1.415 (2) | C18—H18A | 0.960 |
C9—H9 | 0.930 | C18—H18B | 0.960 |
C10—C11 | 1.4006 (19) | C18—H18C | 0.960 |
C10—C13 | 1.457 (2) | N1—H1 | 0.860 |
C11—O1 | 1.3600 (17) | ||
N1—C1—C2 | 129.63 (15) | O2—C13—C14 | 121.16 (16) |
N1—C1—C6 | 109.13 (13) | C10—C13—C14 | 116.04 (13) |
C2—C1—C6 | 121.18 (16) | C13—C14—C15 | 114.35 (14) |
C3—C2—C1 | 117.43 (16) | C13—C14—H14A | 108.7 |
C3—C2—H2 | 121.3 | C15—C14—H14A | 108.7 |
C1—C2—H2 | 121.3 | C13—C14—H14B | 108.7 |
C2—C3—C4 | 123.17 (16) | C15—C14—H14B | 108.7 |
C2—C3—H3 | 118.4 | H14A—C14—H14B | 107.6 |
C4—C3—H3 | 118.4 | O1—C15—C14 | 108.85 (12) |
C5—C4—C3 | 118.55 (16) | O1—C15—C17 | 104.62 (13) |
C5—C4—C18 | 121.14 (17) | C14—C15—C17 | 111.85 (14) |
C3—C4—C18 | 120.31 (17) | O1—C15—C16 | 107.87 (14) |
C4—C5—C6 | 120.24 (15) | C14—C15—C16 | 111.86 (14) |
C4—C5—H5 | 119.9 | C17—C15—C16 | 111.43 (15) |
C6—C5—H5 | 119.9 | C15—C16—H16A | 109.5 |
C5—C6—C1 | 119.41 (15) | C15—C16—H16B | 109.5 |
C5—C6—C7 | 134.19 (14) | H16A—C16—H16B | 109.5 |
C1—C6—C7 | 106.40 (13) | C15—C16—H16C | 109.5 |
C12—C7—C8 | 119.66 (14) | H16A—C16—H16C | 109.5 |
C12—C7—C6 | 106.39 (12) | H16B—C16—H16C | 109.5 |
C8—C7—C6 | 133.94 (14) | C15—C17—H17A | 109.5 |
C9—C8—C7 | 118.57 (14) | C15—C17—H17B | 109.5 |
C9—C8—H8 | 120.7 | H17A—C17—H17B | 109.5 |
C7—C8—H8 | 120.7 | C15—C17—H17C | 109.5 |
C8—C9—C10 | 121.97 (14) | H17A—C17—H17C | 109.5 |
C8—C9—H9 | 119.0 | H17B—C17—H17C | 109.5 |
C10—C9—H9 | 119.0 | C4—C18—H18A | 109.5 |
C11—C10—C9 | 119.82 (14) | C4—C18—H18B | 109.5 |
C11—C10—C13 | 118.46 (14) | H18A—C18—H18B | 109.5 |
C9—C10—C13 | 121.64 (13) | C4—C18—H18C | 109.5 |
O1—C11—C12 | 117.89 (12) | H18A—C18—H18C | 109.5 |
O1—C11—C10 | 124.19 (14) | H18B—C18—H18C | 109.5 |
C12—C11—C10 | 117.92 (13) | C1—N1—C12 | 108.56 (12) |
N1—C12—C11 | 128.43 (13) | C1—N1—H1 | 125.7 |
N1—C12—C7 | 109.52 (13) | C12—N1—H1 | 125.7 |
C11—C12—C7 | 122.03 (13) | C11—O1—C15 | 116.44 (11) |
O2—C13—C10 | 122.73 (16) | ||
N1—C1—C2—C3 | −177.57 (15) | O1—C11—C12—N1 | −1.0 (2) |
C6—C1—C2—C3 | −0.7 (2) | C10—C11—C12—N1 | 179.38 (14) |
C1—C2—C3—C4 | −0.8 (3) | O1—C11—C12—C7 | −178.97 (13) |
C2—C3—C4—C5 | 1.8 (2) | C10—C11—C12—C7 | 1.4 (2) |
C2—C3—C4—C18 | −177.69 (17) | C8—C7—C12—N1 | −177.97 (13) |
C3—C4—C5—C6 | −1.3 (2) | C6—C7—C12—N1 | 0.88 (16) |
C18—C4—C5—C6 | 178.20 (15) | C8—C7—C12—C11 | 0.4 (2) |
C4—C5—C6—C1 | −0.1 (2) | C6—C7—C12—C11 | 179.20 (12) |
C4—C5—C6—C7 | 178.32 (15) | C11—C10—C13—O2 | −175.96 (15) |
N1—C1—C6—C5 | 178.62 (13) | C9—C10—C13—O2 | 0.9 (2) |
C2—C1—C6—C5 | 1.2 (2) | C11—C10—C13—C14 | 1.0 (2) |
N1—C1—C6—C7 | −0.24 (16) | C9—C10—C13—C14 | 177.85 (14) |
C2—C1—C6—C7 | −177.66 (14) | O2—C13—C14—C15 | −155.34 (16) |
C5—C6—C7—C12 | −178.99 (15) | C10—C13—C14—C15 | 27.62 (19) |
C1—C6—C7—C12 | −0.39 (16) | C13—C14—C15—O1 | −51.15 (17) |
C5—C6—C7—C8 | −0.4 (3) | C13—C14—C15—C17 | −166.25 (14) |
C1—C6—C7—C8 | 178.22 (16) | C13—C14—C15—C16 | 67.95 (19) |
C12—C7—C8—C9 | −1.4 (2) | C2—C1—N1—C12 | 177.92 (16) |
C6—C7—C8—C9 | −179.89 (16) | C6—C1—N1—C12 | 0.78 (17) |
C7—C8—C9—C10 | 0.7 (2) | C11—C12—N1—C1 | −179.23 (14) |
C8—C9—C10—C11 | 1.0 (2) | C7—C12—N1—C1 | −1.04 (17) |
C8—C9—C10—C13 | −175.75 (15) | C12—C11—O1—C15 | 158.45 (12) |
C9—C10—C11—O1 | 178.33 (13) | C10—C11—O1—C15 | −21.94 (19) |
C13—C10—C11—O1 | −4.8 (2) | C14—C15—O1—C11 | 48.52 (16) |
C9—C10—C11—C12 | −2.1 (2) | C17—C15—O1—C11 | 168.22 (13) |
C13—C10—C11—C12 | 174.82 (13) | C16—C15—O1—C11 | −73.05 (16) |
D—H···A | D—H | H···A | D···A | D—H···A |
N1—H1···O2i | 0.86 | 2.09 | 2.8093 (17) | 141 |
C14—H14A···Cg1ii | 0.97 | 2.58 | 3.534 (2) | 168 |
C18—H18B···Cg1iii | 0.96 | 3.00 | 3.881 (2) | 153 |
Symmetry codes: (i) −x+1/2, y−1/2, −z+1/2; (ii) x+1, y, z; (iii) x−1, y, z. |
Experimental details
Crystal data | |
Chemical formula | C18H17NO2 |
Mr | 279.33 |
Crystal system, space group | Monoclinic, P21/n |
Temperature (K) | 298 |
a, b, c (Å) | 6.7323 (3), 14.3303 (7), 15.6502 (8) |
β (°) | 99.152 (1) |
V (Å3) | 1490.65 (12) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 0.08 |
Crystal size (mm) | 0.47 × 0.43 × 0.17 |
Data collection | |
Diffractometer | Bruker SMART APEX CCD |
Absorption correction | Multi-scan (SADABS; Bruker, 2007) |
Tmin, Tmax | 0.906, 0.986 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 11129, 3676, 2866 |
Rint | 0.027 |
(sin θ/λ)max (Å−1) | 0.667 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.055, 0.150, 1.06 |
No. of reflections | 3676 |
No. of parameters | 193 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.20, −0.20 |
Computer programs: SMART (Bruker, 2003), SAINT-Plus (Bruker, 2003), SHELXTL (Bruker, 2003).
D—H···A | D—H | H···A | D···A | D—H···A |
N1—H1···O2i | 0.86 | 2.09 | 2.8093 (17) | 141 |
C14—H14A···Cg1ii | 0.97 | 2.58 | 3.534 (2) | 168 |
C18—H18B···Cg1iii | 0.96 | 3.00 | 3.881 (2) | 153 |
Symmetry codes: (i) −x+1/2, y−1/2, −z+1/2; (ii) x+1, y, z; (iii) x−1, y, z. |
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A low-yield synthesis of the title compound has been reported previously by Patel (1982). Using trifluoroacetic acid as the acylating agent (Rajendra Prasad & Vijayalakshmi (1994); Sowmithran & Rajendra Prasad (1986)), we have prepared the compound in excellent yield as the sole product of a one-step synthesis (Fig. 1). Crystallization from ethanol yielded crystals suitable for X-ray diffraction analysis. In the crystal, the molecule is essentially planar (Fig. 2), with only atom C15 and the adjacent two methyl groups (C16, C17) of the 2,2-dimethyl-2H-pyran-4(3H)-one unit deviating significantly from the mean plane of the other atoms. The RMS deviation for all non-H atoms excluding C15, C16 and C17 is 0.045 Å and the deviation from the plane is -0.590 (2), 2.102 (2) and -0.221 (2) Å for C15, C16 and C17, respectively.
Intermolecular N—H···O hydrogen bonds are formed, with the keto oxygen atom O2 acting as the acceptor, and C—H···π contacts are observed between C14 and the π system of the pyrrole ring, with a C—H···Cgii distance of 2.58 Å (symmetry code: (ii) 1 + x, y, z). The other face of the pyrrole ring accepts another significantly longer C—H···π contact from the methyl group C18, with a C—H···Cgiii distance of 3.00 Å (symmetry code (iii): -1 + x, y, z). While the flat molecules are in part parallel to each other, no strong π..π stacking interactions are observed.
The N—H···O hydrogen bonds connect individual molecules into infinite chains along the b-axis. The two types of C—H···π contacts are formed between molecules adjacent along the a-axis. Both types of highlighted interactions are formed between molecules lying within layers parallel to the (001) planes, and the c-axis spans two such layers (Fig. 3).