organic compounds
2-Amino-7,7-dimethyl-5-oxo-4-(p-tolyl)-5,6,7,8-tetrahydro-4H-chromene-3-carbonitrile
aPost-Graduate Department of Physics & Electronics, University of Jammu, Jammu Tawi 180 006, India, and bLaboratory of Natural Products & Organic Synthesis, Department of Chemistry, Visva-Bharati University, Santiniketan 731 235, West Bengal, India
*Correspondence e-mail: vivek_gupta2k2@hotmail.com
In the title molecule, C19H20N2O2, the cyclohexene ring adopts a sofa conformation, while the pyran ring adopts a flattened boat conformation. In the crystal, molecules are linked by N—H⋯N and N—H⋯O hydrogen bonds, forming a two-dimensional network parallel to (010).
Related literature
For background to compounds containing the 4H-pyran unit, see: Brahmachari (2010); Hatakeyama et al. (1988). For the biological activity of compounds containing a tetrahydrobenzo[b]pyran ring system, see: Andreani & Lapi (1960); Bonsignore et al. (1993); Brahmachari (2011); Konkoy et al. (2001). For 2-amino-4H-pyrans as photoactive materials, see: Armetso et al. (1989). For the synthesis of related compounds, see: Jin et al. (2004); Balalaie et al. (2007). For related structures, see: Tu et al. (2001); Wang (2011). For ring conformations, see: Duax et al. (1975).
Experimental
Crystal data
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Refinement
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Data collection: CrysAlis PRO (Oxford Diffraction, 2010); cell CrysAlis PRO; data reduction: CrysAlis PRO; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 (Farrugia, 1997); software used to prepare material for publication: PLATON (Spek, 2009).
Supporting information
https://doi.org/10.1107/S1600536812033570/lh5503sup1.cif
contains datablocks I, global. DOI:Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S1600536812033570/lh5503Isup2.hkl
Supporting information file. DOI: https://doi.org/10.1107/S1600536812033570/lh5503Isup3.cml
The synthesis of the title compounds was carried out via one-pot multi-component reaction in aqueous ethanol using low-cost and environmentally benign sodium formate as catalyst at room temperature. An oven-dried screw cap test tube was charged with a magnetic stir bar, p-methylbenzaldehyde (0.12 g, 1 mmol), malononitrile (0.066 g, 1 mmol) and sodium formate (0.136 g, 20 mol %) in 5 ml aqueous ethanol. The reaction mixture was then started to stir vigorously and after 20 min 1 mmol of dimedone (0.14 g) was added, and continued to stir. After completion of the overall reaction (2 h) as monitored by TLC, a white solid was precipitated out, filtered off, and washed with aqueous ethanol. Recrystallization from ethanol afforded the title compound as white block-shaped crystals (252 mg, yield 82%) with the m.p. 492–494 K (lit. 492–495 K) (Balalaie et al., 2007). Rf 0.82 (EtOAc). White solid; FT—IR (KBr) νmax 3375, 3256, 3180, 2961, 2920, 2885, 2187, 1677, 1637, 1607, 1512, 1460, 1414, 1366, 1215, 1137, 1030, 825, 764, 565 cm-1; 1H-NMR (DMSO-d6, 400 MHz) & 13 C-NMR (DMSO-d6; 100 MHz) data are in excellent agreement with literature values (Jin et al., 2004; Balalaie et al., 2007); TOF-MS: calculated for C19H20N2O2Na 331.1422 [M + Na]+; found 331.1426. For crystallization 60 mg of the compound was dissolved in 20 ml mixture of ethanol and water (5:1) and left for several days at ambient temperature which yielded white block-shaped crystals.
H131 and H132 attached to N13 were located in a difference map and refined isotropically. The remaining H atoms were positioned geometrically and were treated as riding on their parent C atoms, with C—H distances of 0.93–0.98 Å; and with Uiso(H) = 1.2Ueq(C), except for the methyl groups where Uiso(H) = 1.5Ueq(C).
4H-Pyran units constitute structural features of a broad range of bioactive natural products (Brahmachari, 2010; Hatakeyama et al., 1988). The tetrahydrobenzo[b]pyran ring is of particular interest because compounds bearing this structural motif exhibit diverse biological activities such as spasmolytic, anticancer and anti-anaphylactin agents (Andreani et al., 1960; Bonsignore et al., 1993), anti-Alzheimer's disease (Brahmachari, 2011), anti-Huntington's disease, anti-Parkinson's disease and anti-HIV (Konkoy et al., 2001). 2-Amino-4H-pyrans have also been found to be useful as photoactive materials (Armetso et al., 1989). Hence, investigation of the structural features of biologically relevant tetrahydrobenzo[b]pyran derivatives is of both scientific and practical interest. In continuation of our efforts to develop useful synthetic protocols for biologically significant molecules, we herein report an efficient and environmentally benign synthesis and the
of the title compound. The bond lengths and angles of the title compound are normal and correspond to those observed in related structures (Tu et al., 2001; Wang, 2011). The cyclohexene ring adopts a sofa conformation while the pyran ring adopts a flattened boat conformation with asymmetry parameters [ΔCs(C7) = 5.71] and [ΔCs (O1—C4) = 0.08; ΔCs (C2—C3) = 9.8)] respectively (Duax et al., 1975). In the intermolecular N—H···N and N—H···O hydrogen bonds link the molecules into a two-dimensional network parallel to (010) (Fig.2).For background to compounds containing the 4H-pyran unit, see: Brahmachari (2010); Hatakeyama et al. (1988). For the biological activity of compounds containing a tetrahydrobenzo[b]pyran ring system, see: Andreani & Lapi (1960); Bonsignore et al. (1993); Brahmachari (2011); Konkoy et al. (2001). For 2-amino-4H-pyrans as photoactive materials, see: Armetso et al. (1989). For the synthesis of related compounds, see: Jin et al. (2004); Balalaie et al. (2007). For related structures, see: Tu et al. (2001); Wang (2011). For ring conformations, see: Duax et al. (1975).
Data collection: CrysAlis PRO (Oxford Diffraction, 2010); cell
CrysAlis PRO (Oxford Diffraction, 2010); data reduction: CrysAlis PRO (Oxford Diffraction, 2010); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 (Farrugia, 1997); software used to prepare material for publication: PLATON (Spek, 2009).C19H20N2O2 | F(000) = 656 |
Mr = 308.37 | Dx = 1.276 Mg m−3 |
Monoclinic, P21/n | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -P 2yn | Cell parameters from 7806 reflections |
a = 9.4622 (3) Å | θ = 3.6–29.1° |
b = 16.8820 (5) Å | µ = 0.08 mm−1 |
c = 10.8301 (4) Å | T = 293 K |
β = 111.842 (4)° | Block, white |
V = 1605.82 (9) Å3 | 0.30 × 0.20 × 0.20 mm |
Z = 4 |
Oxford Diffraction Xcalibur Sapphire3 diffractometer | 3149 independent reflections |
Radiation source: fine-focus sealed tube | 2428 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.037 |
Detector resolution: 16.1049 pixels mm-1 | θmax = 26.0°, θmin = 3.6° |
ω scans | h = −11→11 |
Absorption correction: multi-scan (CrysAlis PRO; Oxford Diffraction, 2010) | k = −20→20 |
Tmin = 0.862, Tmax = 1.000 | l = −13→13 |
18449 measured reflections |
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)] = 0.046 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.115 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.05 | w = 1/[σ2(Fo2) + (0.0501P)2 + 0.4013P] where P = (Fo2 + 2Fc2)/3 |
3149 reflections | (Δ/σ)max = 0.001 |
219 parameters | Δρmax = 0.20 e Å−3 |
0 restraints | Δρmin = −0.22 e Å−3 |
C19H20N2O2 | V = 1605.82 (9) Å3 |
Mr = 308.37 | Z = 4 |
Monoclinic, P21/n | Mo Kα radiation |
a = 9.4622 (3) Å | µ = 0.08 mm−1 |
b = 16.8820 (5) Å | T = 293 K |
c = 10.8301 (4) Å | 0.30 × 0.20 × 0.20 mm |
β = 111.842 (4)° |
Oxford Diffraction Xcalibur Sapphire3 diffractometer | 3149 independent reflections |
Absorption correction: multi-scan (CrysAlis PRO; Oxford Diffraction, 2010) | 2428 reflections with I > 2σ(I) |
Tmin = 0.862, Tmax = 1.000 | Rint = 0.037 |
18449 measured reflections |
R[F2 > 2σ(F2)] = 0.046 | 0 restraints |
wR(F2) = 0.115 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.05 | Δρmax = 0.20 e Å−3 |
3149 reflections | Δρmin = −0.22 e Å−3 |
219 parameters |
Experimental. Absorption correction: CrysAlis PRO, Oxford Diffraction Ltd., Version 1.171.34.40 (release 27–08-2010 CrysAlis171. NET) (compiled Aug 27 2010,11:50:40) Empirical absorption correction using spherical harmonics, implemented in SCALE3 ABSPACK scaling algorithm. |
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 | ||
O1 | 0.62616 (12) | 0.12747 (6) | 0.06792 (11) | 0.0370 (3) | |
C1' | 0.87094 (17) | 0.17332 (9) | 0.42111 (15) | 0.0324 (4) | |
C2' | 1.00784 (18) | 0.14575 (11) | 0.41998 (17) | 0.0433 (4) | |
H2' | 1.0343 | 0.1568 | 0.3472 | 0.052* | |
C3' | 1.1067 (2) | 0.10204 (11) | 0.52474 (19) | 0.0498 (5) | |
H3' | 1.1978 | 0.0842 | 0.5206 | 0.060* | |
C4' | 1.0732 (2) | 0.08433 (10) | 0.63476 (17) | 0.0442 (4) | |
C5' | 0.9371 (2) | 0.11238 (11) | 0.63673 (18) | 0.0504 (5) | |
H5' | 0.9118 | 0.1018 | 0.7103 | 0.060* | |
C6' | 0.8370 (2) | 0.15591 (11) | 0.53232 (17) | 0.0456 (4) | |
H6' | 0.7459 | 0.1737 | 0.5367 | 0.055* | |
C7' | 1.1810 (2) | 0.03593 (13) | 0.7475 (2) | 0.0645 (6) | |
H7'1 | 1.1854 | −0.0172 | 0.7175 | 0.097* | |
H7'2 | 1.1456 | 0.0350 | 0.8199 | 0.097* | |
H7'3 | 1.2807 | 0.0592 | 0.7770 | 0.097* | |
C2 | 0.74563 (17) | 0.17699 (9) | 0.07890 (15) | 0.0324 (4) | |
C3 | 0.80680 (17) | 0.22511 (9) | 0.18489 (15) | 0.0325 (4) | |
C4 | 0.75981 (17) | 0.22126 (9) | 0.30428 (15) | 0.0325 (4) | |
H4 | 0.7564 | 0.2755 | 0.3353 | 0.039* | |
O5 | 0.53082 (14) | 0.26138 (8) | 0.40897 (12) | 0.0488 (3) | |
C5 | 0.49500 (18) | 0.21056 (10) | 0.32139 (16) | 0.0372 (4) | |
C6 | 0.33944 (19) | 0.17324 (11) | 0.27258 (19) | 0.0455 (4) | |
H6A | 0.2688 | 0.2083 | 0.2076 | 0.055* | |
H6B | 0.3062 | 0.1686 | 0.3469 | 0.055* | |
C7 | 0.33113 (18) | 0.09159 (10) | 0.20960 (17) | 0.0386 (4) | |
C8 | 0.39789 (18) | 0.09955 (11) | 0.10153 (17) | 0.0406 (4) | |
H8A | 0.4110 | 0.0472 | 0.0705 | 0.049* | |
H8B | 0.3267 | 0.1284 | 0.0267 | 0.049* | |
C9 | 0.54697 (16) | 0.14144 (9) | 0.14978 (15) | 0.0321 (4) | |
C10 | 0.60023 (17) | 0.18777 (9) | 0.25695 (15) | 0.0312 (4) | |
C11 | 0.4198 (2) | 0.03164 (12) | 0.3151 (2) | 0.0568 (5) | |
H11A | 0.5238 | 0.0486 | 0.3562 | 0.085* | |
H11B | 0.4164 | −0.0192 | 0.2743 | 0.085* | |
H11C | 0.3752 | 0.0277 | 0.3813 | 0.085* | |
C12 | 0.1651 (2) | 0.06452 (13) | 0.1450 (2) | 0.0579 (5) | |
H12A | 0.1612 | 0.0141 | 0.1030 | 0.087* | |
H12B | 0.1084 | 0.1027 | 0.0797 | 0.087* | |
H12C | 0.1218 | 0.0598 | 0.2120 | 0.087* | |
N13 | 0.78732 (18) | 0.16693 (10) | −0.02573 (15) | 0.0432 (4) | |
C14 | 0.92224 (19) | 0.27927 (10) | 0.18699 (16) | 0.0396 (4) | |
N15 | 1.01708 (19) | 0.32308 (10) | 0.19332 (17) | 0.0578 (5) | |
H131 | 0.864 (2) | 0.1956 (12) | −0.0300 (19) | 0.055 (6)* | |
H132 | 0.716 (2) | 0.1541 (12) | −0.101 (2) | 0.059 (6)* |
U11 | U22 | U33 | U12 | U13 | U23 | |
O1 | 0.0355 (6) | 0.0427 (6) | 0.0391 (6) | −0.0084 (5) | 0.0212 (5) | −0.0064 (5) |
C1' | 0.0317 (8) | 0.0332 (8) | 0.0311 (8) | −0.0050 (6) | 0.0102 (6) | −0.0051 (6) |
C2' | 0.0344 (9) | 0.0567 (11) | 0.0404 (9) | 0.0021 (8) | 0.0159 (7) | 0.0041 (8) |
C3' | 0.0340 (9) | 0.0609 (12) | 0.0502 (11) | 0.0054 (8) | 0.0108 (8) | 0.0035 (9) |
C4' | 0.0430 (10) | 0.0388 (10) | 0.0396 (10) | −0.0060 (8) | 0.0024 (8) | −0.0022 (7) |
C5' | 0.0597 (12) | 0.0567 (12) | 0.0361 (9) | −0.0019 (9) | 0.0194 (9) | 0.0032 (8) |
C6' | 0.0459 (10) | 0.0552 (11) | 0.0400 (10) | 0.0052 (8) | 0.0210 (8) | 0.0014 (8) |
C7' | 0.0638 (13) | 0.0584 (13) | 0.0519 (12) | 0.0001 (10) | −0.0010 (10) | 0.0096 (10) |
C2 | 0.0269 (7) | 0.0373 (9) | 0.0351 (8) | −0.0002 (6) | 0.0139 (6) | 0.0059 (7) |
C3 | 0.0289 (8) | 0.0349 (9) | 0.0345 (8) | −0.0019 (6) | 0.0127 (6) | 0.0044 (6) |
C4 | 0.0311 (8) | 0.0311 (8) | 0.0366 (8) | −0.0005 (6) | 0.0141 (7) | −0.0034 (6) |
O5 | 0.0463 (7) | 0.0556 (8) | 0.0513 (7) | 0.0043 (6) | 0.0260 (6) | −0.0126 (6) |
C5 | 0.0367 (9) | 0.0374 (9) | 0.0412 (9) | 0.0067 (7) | 0.0188 (7) | 0.0033 (7) |
C6 | 0.0359 (9) | 0.0487 (11) | 0.0608 (11) | 0.0036 (8) | 0.0284 (8) | −0.0003 (8) |
C7 | 0.0317 (8) | 0.0417 (10) | 0.0482 (10) | −0.0005 (7) | 0.0215 (7) | 0.0046 (7) |
C8 | 0.0322 (8) | 0.0479 (10) | 0.0422 (9) | −0.0069 (7) | 0.0146 (7) | −0.0028 (7) |
C9 | 0.0289 (8) | 0.0362 (9) | 0.0343 (8) | 0.0034 (6) | 0.0156 (7) | 0.0046 (7) |
C10 | 0.0290 (8) | 0.0327 (8) | 0.0345 (8) | 0.0027 (6) | 0.0147 (6) | 0.0018 (6) |
C11 | 0.0588 (12) | 0.0526 (12) | 0.0643 (13) | 0.0024 (9) | 0.0290 (10) | 0.0162 (10) |
C12 | 0.0373 (10) | 0.0653 (13) | 0.0772 (14) | −0.0096 (9) | 0.0283 (10) | −0.0017 (11) |
N13 | 0.0352 (8) | 0.0630 (10) | 0.0359 (8) | −0.0091 (7) | 0.0184 (7) | 0.0004 (7) |
C14 | 0.0355 (9) | 0.0425 (10) | 0.0399 (9) | −0.0034 (8) | 0.0132 (7) | 0.0035 (7) |
N15 | 0.0501 (9) | 0.0570 (10) | 0.0648 (11) | −0.0187 (8) | 0.0198 (8) | 0.0028 (8) |
O1—C2 | 1.3751 (18) | O5—C5 | 1.229 (2) |
O1—C9 | 1.3774 (18) | C5—C10 | 1.464 (2) |
C1'—C2' | 1.381 (2) | C5—C6 | 1.505 (2) |
C1'—C6' | 1.389 (2) | C6—C7 | 1.527 (2) |
C1'—C4 | 1.540 (2) | C6—H6A | 0.9700 |
C2'—C3' | 1.384 (2) | C6—H6B | 0.9700 |
C2'—H2' | 0.9300 | C7—C11 | 1.523 (2) |
C3'—C4' | 1.375 (3) | C7—C8 | 1.529 (2) |
C3'—H3' | 0.9300 | C7—C12 | 1.532 (2) |
C4'—C5' | 1.380 (3) | C8—C9 | 1.488 (2) |
C4'—C7' | 1.508 (2) | C8—H8A | 0.9700 |
C5'—C6' | 1.385 (3) | C8—H8B | 0.9700 |
C5'—H5' | 0.9300 | C9—C10 | 1.333 (2) |
C6'—H6' | 0.9300 | C11—H11A | 0.9600 |
C7'—H7'1 | 0.9600 | C11—H11B | 0.9600 |
C7'—H7'2 | 0.9600 | C11—H11C | 0.9600 |
C7'—H7'3 | 0.9600 | C12—H12A | 0.9600 |
C2—N13 | 1.342 (2) | C12—H12B | 0.9600 |
C2—C3 | 1.348 (2) | C12—H12C | 0.9600 |
C3—C14 | 1.418 (2) | N13—H131 | 0.88 (2) |
C3—C4 | 1.517 (2) | N13—H132 | 0.87 (2) |
C4—C10 | 1.512 (2) | C14—N15 | 1.145 (2) |
C4—H4 | 0.9800 | ||
C2—O1—C9 | 117.83 (12) | C5—C6—C7 | 114.58 (13) |
C2'—C1'—C6' | 117.19 (15) | C5—C6—H6A | 108.6 |
C2'—C1'—C4 | 121.74 (14) | C7—C6—H6A | 108.6 |
C6'—C1'—C4 | 121.08 (14) | C5—C6—H6B | 108.6 |
C1'—C2'—C3' | 121.49 (17) | C7—C6—H6B | 108.6 |
C1'—C2'—H2' | 119.3 | H6A—C6—H6B | 107.6 |
C3'—C2'—H2' | 119.3 | C11—C7—C6 | 110.02 (15) |
C4'—C3'—C2' | 121.53 (17) | C11—C7—C8 | 111.30 (14) |
C4'—C3'—H3' | 119.2 | C6—C7—C8 | 107.18 (14) |
C2'—C3'—H3' | 119.2 | C11—C7—C12 | 109.22 (15) |
C3'—C4'—C5' | 117.14 (16) | C6—C7—C12 | 110.29 (14) |
C3'—C4'—C7' | 120.99 (18) | C8—C7—C12 | 108.80 (15) |
C5'—C4'—C7' | 121.87 (18) | C9—C8—C7 | 112.37 (14) |
C4'—C5'—C6' | 121.89 (17) | C9—C8—H8A | 109.1 |
C4'—C5'—H5' | 119.1 | C7—C8—H8A | 109.1 |
C6'—C5'—H5' | 119.1 | C9—C8—H8B | 109.1 |
C5'—C6'—C1' | 120.77 (17) | C7—C8—H8B | 109.1 |
C5'—C6'—H6' | 119.6 | H8A—C8—H8B | 107.9 |
C1'—C6'—H6' | 119.6 | C10—C9—O1 | 122.74 (14) |
C4'—C7'—H7'1 | 109.5 | C10—C9—C8 | 125.90 (14) |
C4'—C7'—H7'2 | 109.5 | O1—C9—C8 | 111.36 (13) |
H7'1—C7'—H7'2 | 109.5 | C9—C10—C5 | 117.73 (14) |
C4'—C7'—H7'3 | 109.5 | C9—C10—C4 | 121.39 (14) |
H7'1—C7'—H7'3 | 109.5 | C5—C10—C4 | 120.70 (14) |
H7'2—C7'—H7'3 | 109.5 | C7—C11—H11A | 109.5 |
N13—C2—C3 | 128.83 (15) | C7—C11—H11B | 109.5 |
N13—C2—O1 | 109.91 (14) | H11A—C11—H11B | 109.5 |
C3—C2—O1 | 121.24 (14) | C7—C11—H11C | 109.5 |
C2—C3—C14 | 119.09 (15) | H11A—C11—H11C | 109.5 |
C2—C3—C4 | 122.04 (13) | H11B—C11—H11C | 109.5 |
C14—C3—C4 | 118.83 (14) | C7—C12—H12A | 109.5 |
C10—C4—C3 | 107.42 (12) | C7—C12—H12B | 109.5 |
C10—C4—C1' | 111.87 (12) | H12A—C12—H12B | 109.5 |
C3—C4—C1' | 113.31 (13) | C7—C12—H12C | 109.5 |
C10—C4—H4 | 108.0 | H12A—C12—H12C | 109.5 |
C3—C4—H4 | 108.0 | H12B—C12—H12C | 109.5 |
C1'—C4—H4 | 108.0 | C2—N13—H131 | 118.5 (13) |
O5—C5—C10 | 120.66 (15) | C2—N13—H132 | 116.8 (14) |
O5—C5—C6 | 121.07 (15) | H131—N13—H132 | 116.9 (19) |
C10—C5—C6 | 118.19 (15) | N15—C14—C3 | 177.67 (18) |
C6'—C1'—C2'—C3' | 0.5 (3) | C10—C5—C6—C7 | 26.8 (2) |
C4—C1'—C2'—C3' | −179.38 (16) | C5—C6—C7—C11 | 67.88 (19) |
C1'—C2'—C3'—C4' | −0.2 (3) | C5—C6—C7—C8 | −53.27 (19) |
C2'—C3'—C4'—C5' | −0.4 (3) | C5—C6—C7—C12 | −171.57 (15) |
C2'—C3'—C4'—C7' | 179.35 (17) | C11—C7—C8—C9 | −71.62 (19) |
C3'—C4'—C5'—C6' | 0.6 (3) | C6—C7—C8—C9 | 48.72 (18) |
C7'—C4'—C5'—C6' | −179.09 (18) | C12—C7—C8—C9 | 167.98 (15) |
C4'—C5'—C6'—C1' | −0.3 (3) | C2—O1—C9—C10 | −15.5 (2) |
C2'—C1'—C6'—C5' | −0.2 (3) | C2—O1—C9—C8 | 163.73 (13) |
C4—C1'—C6'—C5' | 179.64 (15) | C7—C8—C9—C10 | −19.0 (2) |
C9—O1—C2—N13 | −166.15 (13) | C7—C8—C9—O1 | 161.72 (13) |
C9—O1—C2—C3 | 15.4 (2) | O1—C9—C10—C5 | 168.43 (13) |
N13—C2—C3—C14 | 6.5 (3) | C8—C9—C10—C5 | −10.7 (2) |
O1—C2—C3—C14 | −175.37 (14) | O1—C9—C10—C4 | −6.7 (2) |
N13—C2—C3—C4 | −171.42 (16) | C8—C9—C10—C4 | 174.14 (15) |
O1—C2—C3—C4 | 6.7 (2) | O5—C5—C10—C9 | −170.15 (15) |
C2—C3—C4—C10 | −25.3 (2) | C6—C5—C10—C9 | 6.7 (2) |
C14—C3—C4—C10 | 156.78 (14) | O5—C5—C10—C4 | 5.0 (2) |
C2—C3—C4—C1' | 98.75 (17) | C6—C5—C10—C4 | −178.09 (14) |
C14—C3—C4—C1' | −79.14 (18) | C3—C4—C10—C9 | 25.20 (19) |
C2'—C1'—C4—C10 | 129.01 (16) | C1'—C4—C10—C9 | −99.76 (17) |
C6'—C1'—C4—C10 | −50.87 (19) | C3—C4—C10—C5 | −149.80 (14) |
C2'—C1'—C4—C3 | 7.4 (2) | C1'—C4—C10—C5 | 85.24 (17) |
C6'—C1'—C4—C3 | −172.49 (15) | C2—C3—C14—N15 | −157 (5) |
O5—C5—C6—C7 | −156.36 (16) | C4—C3—C14—N15 | 20 (5) |
D—H···A | D—H | H···A | D···A | D—H···A |
N13—H131···O5i | 0.89 (2) | 2.06 (2) | 2.913 (2) | 161 (2) |
N13—H132···N15ii | 0.87 (2) | 2.35 (2) | 3.168 (2) | 156 (2) |
Symmetry codes: (i) x+1/2, −y+1/2, z−1/2; (ii) x−1/2, −y+1/2, z−1/2. |
Experimental details
Crystal data | |
Chemical formula | C19H20N2O2 |
Mr | 308.37 |
Crystal system, space group | Monoclinic, P21/n |
Temperature (K) | 293 |
a, b, c (Å) | 9.4622 (3), 16.8820 (5), 10.8301 (4) |
β (°) | 111.842 (4) |
V (Å3) | 1605.82 (9) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 0.08 |
Crystal size (mm) | 0.30 × 0.20 × 0.20 |
Data collection | |
Diffractometer | Oxford Diffraction Xcalibur Sapphire3 |
Absorption correction | Multi-scan (CrysAlis PRO; Oxford Diffraction, 2010) |
Tmin, Tmax | 0.862, 1.000 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 18449, 3149, 2428 |
Rint | 0.037 |
(sin θ/λ)max (Å−1) | 0.617 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.046, 0.115, 1.05 |
No. of reflections | 3149 |
No. of parameters | 219 |
H-atom treatment | H atoms treated by a mixture of independent and constrained refinement |
Δρmax, Δρmin (e Å−3) | 0.20, −0.22 |
Computer programs: CrysAlis PRO (Oxford Diffraction, 2010), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), ORTEP-3 (Farrugia, 1997), PLATON (Spek, 2009).
D—H···A | D—H | H···A | D···A | D—H···A |
N13—H131···O5i | 0.89 (2) | 2.06 (2) | 2.913 (2) | 161 (2) |
N13—H132···N15ii | 0.87 (2) | 2.35 (2) | 3.168 (2) | 156 (2) |
Symmetry codes: (i) x+1/2, −y+1/2, z−1/2; (ii) x−1/2, −y+1/2, z−1/2. |
Acknowledgements
SL is grateful to the CSIR, New Delhi, for the award of a Senior Research Fellowship. BB is grateful to the UGC, New Delhi, for the awarding of a Junior Research Fellowship. RK acknowledges the Department of Science & Technology for the single-crystal X-ray diffractometer sanctioned as a National Facility under project No. SR/S2/CMP-47/2003.
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This is an open-access article distributed under the terms of the Creative Commons Attribution (CC-BY) Licence, which permits unrestricted use, distribution, and reproduction in any medium, provided the original authors and source are cited.
4H-Pyran units constitute structural features of a broad range of bioactive natural products (Brahmachari, 2010; Hatakeyama et al., 1988). The tetrahydrobenzo[b]pyran ring is of particular interest because compounds bearing this structural motif exhibit diverse biological activities such as spasmolytic, anticancer and anti-anaphylactin agents (Andreani et al., 1960; Bonsignore et al., 1993), anti-Alzheimer's disease (Brahmachari, 2011), anti-Huntington's disease, anti-Parkinson's disease and anti-HIV (Konkoy et al., 2001). 2-Amino-4H-pyrans have also been found to be useful as photoactive materials (Armetso et al., 1989). Hence, investigation of the structural features of biologically relevant tetrahydrobenzo[b]pyran derivatives is of both scientific and practical interest. In continuation of our efforts to develop useful synthetic protocols for biologically significant molecules, we herein report an efficient and environmentally benign synthesis and the crystal structure of the title compound. The bond lengths and angles of the title compound are normal and correspond to those observed in related structures (Tu et al., 2001; Wang, 2011). The cyclohexene ring adopts a sofa conformation while the pyran ring adopts a flattened boat conformation with asymmetry parameters [ΔCs(C7) = 5.71] and [ΔCs (O1—C4) = 0.08; ΔCs (C2—C3) = 9.8)] respectively (Duax et al., 1975). In the crystal structure, intermolecular N—H···N and N—H···O hydrogen bonds link the molecules into a two-dimensional network parallel to (010) (Fig.2).