Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270101002682/bm1442sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S0108270101002682/bm1442Isup2.hkl | |
Structure factor file (CIF format) https://doi.org/10.1107/S0108270101002682/bm1442IIsup3.hkl |
CCDC references: 164669; 164670
For related literature, see: Alajarin et al. (1995); Allen et al. (1987); Bellanato et al. (1987, 1988); Bossert & Vater (1989); Bossert et al. (1981); Florencio & Garcia-Blanco (1987); Junek, Aigner & ? (1970); Kislyi et al. (1999a, 1999b); Klokol et al. (1987); Kokubun & Reuter (1984); Marco et al. (1993); Nesterov et al. (1985); Rappoport & Ladkani (1974); Rowlend & Taylor (1996); Samet et al. (1996); Sharanina et al. (1986); Shestopalov et al. (1991); Triggle et al. (1980); Wang et al. (1989).
Compounds (I) and (II) were prepared by the reaction of m-nitrophenyl aldehyde (0.01 mol) with acetylacetone (0.01 mol) and ethyl acetoacetate (0.01 mol), respectively, in the presence of a catalytic amount of morpholine in ethanol (20 ml) under reflux (Sharanina et al., 1986). The precipitates were isolated and recrystallized from ethanol [m.p. 492 K for (I) and 457 K for (II); yield 90% for (I) and 86% for (II)]. Colourless crystals of (I) and (II) suitable for X-ray analysis were obtained by isothermal evaporation from ethanolic solutions.
AUTHOR - please check these details: H atoms were located from difference Fourier syntheses and idealized for refinement with N—H 0.86 Å, and C—H 0.93, 0.96 and 0.98 Å for aryl, methyl and methine H atoms, respectively, and with Uiso(H) = xUeq(N/C), where x = 1.5 for methyl H atoms and 1.2 for all others.
The synthesis of hydrogenated compounds has been extensively studied, due to their biological properties. For example, derivatives of 1,4-dihydropyridine exhibit high biological activities as calcium channel blockers (Bossert et al., 1981) and as calcium agonists or antagonists (Triggle et al., 1980; Kokubun & Reuter, 1984; Bossert & Vater, 1989; Wang et al., 1989; Alajarin et al., 1995). 4H-Pyran derivatives have structures similar to those of 1,4-dihydropyridine and elicit the interest of organic chemists as well as of crystallographers. Many different methods have been proposed for the synthesis of 4H-pyran derivatives, for example by Junek & Aigner (1970) and Rappoport & Ladkani (1974). Structural studies of some derivatives of 4H-pyrans by X-ray analysis have been published (Florencio & Garcia-Blanco, 1987; Bellanato et al., 1987, 1988; Lokai et al., 1990; Marco et al., 1993). The present study represents a continuation of our investigations of the structures of 4H-pyran derivatives (Sharanina et al., 1986; Klokol et al., 1987; Shestopalov et al., 1991; Samet et al., 1996; Kislyi et al., 1999a,b). The crystal structures of 5-acetyl-2-amino-6-methyl-4-(3-nitrophenyl)-4H-pyran-3-carbonitrile, (I), and ethyl 6-amino-5-cyano-2-methyl-4-(3-nitrophenyl)-4H-pyrano-3-carboxylate, (II), are presented herein. \sch
The pyran rings in both molecules have boat conformations, with atoms O1 and C4 out of the C2/C3/C5/C6 plane by -0.179 (1) and -0.341 (1) Å, respectively, in (I), and by 0.151 (2) and 0.306 (2) Å, respectively, in (II). The C2/C3/C5/C6 plane is planar to within 0.005 (1) Å for (I) and 0.026 (1) Å for (II). The bending of the ring along O1···C4, C2···C6 and C3···C5 equals 24.0 (1), 15.1 (1) and 22.8 (2)°, respectively, in (I), and 21.2 (1), 12.7 (1) and 20.3 (2)°, respectively, in (II). The heterocycles in (I) and (II), in pyrans with comparable structures, and in derivatives of 1,4-dihydropyridine, for example, nifedipine (Triggle et al., 1980), nimodipine (Wang et al., 1989) and furnidipine (Alajarin et al., 1995), have similar conformations.
The dihedral angle between the pseudo-axial aryl substituent and the C2/C3/C5/C6 plane of the boat of the heterocycle is 84.0 (1)° in (I) and 98.7 (1)° in (II), minimizing possible intramolecular sterical contacts in both molecules. Similar orientations of sterically demanding substituents were found in all previously determined derivatives of 4H-pyrans (Sharanina et al., 1986; Klokol et al., 1987; Shestopalov et al., 1991; Samet et al., 1996; Kislyi et al., 1999a,b; Florencio & Garcia-Blanco, 1987; Bellanato et al., 1988; Lokai et al., 1990; Marco et al., 1993). The value of the angle is close to 90° in practically all known 4H-pyran derivatives containing sterically demanding substituents in the 4-position of the heterocycle.
The nitro groups are slightly rotated from the plane of the phenyl ring of the aryl substituent, by 12.1 (2)° in (I) and 8.4 (2)° in (II). As shown in Figs. 1 and 2, the substituents at C5 of the heterocycle have trans orientations with respect to the C5═C6 double bond. The C6—C5—C8—O2 torsion angle is -179.3 (2)° in (I) and -157.2 (2)° in (II). It is interesting to note that the acetyl substituent has a cis geometry in the 1,4-dihydropyridine derivative described by Nesterov et al. (1985), and ester groups have cis geometry in substituted 4H-pyrans and form intramolecular hydrogen bonds with amino groups (Sharanina et al., 1986; Klokol et al., 1987; Shestopalov et al., 1991).
The bond lengths in the planar fragment N1—C2═C3—C16/C17≡N2 in both structures are different from typical literature values (Allen et al., 1987). This bond length distribution was observed in all derivatives of 4H-pyrans that we investigated and has also been noted in the literature (Samet et al., 1996; Bellanato et al., 1987; Lokai et al., 1990; Marco et al., 1993). This regularity can be explained by the conjugation of bonds in the fragment. However, in the C6═ C5—C8═O2 fragment, located on the opposite side of the pyran ring in both compounds, the bond lengths agree with standard values (Allen et al., 1987) and this confirms the absence of conjugation in this fragment of both molecules. The mutual orientation of substituents of the pyran ring in both molecules gives rise to an intramolecular O2···H4A non-bonded interaction. The length of this interaction is 2.38 Å in (I) and 2.43 Å in (II), less than the sum of the relevant van der Waals radii (Rowlend & Taylor, 1996). The rest of the geometrical parameters in (I) and (II) have standard values (Allen et al., 1987).
The structures of (I) and (II) both exhibit intermolecular N1—H1B···O2(x, y - 1, z) and N1—H1A···N2(2 - x, 1 - y, 1 - z) hydrogen bonds, which connect molecules into infinite tapes along the b axis.
For related literature, see: Alajarin et al. (1995); Allen et al. (1987); Bellanato et al. (1987, 1988); Bossert & Vater (1989); Bossert et al. (1981); Florencio & Garcia-Blanco (1987); Junek, Aigner & ? (1970); Kislyi et al. (1999a, 1999b); Klokol et al. (1987); Kokubun & Reuter (1984); Marco et al. (1993); Nesterov et al. (1985); Rappoport & Ladkani (1974); Rowlend & Taylor (1996); Samet et al. (1996); Sharanina et al. (1986); Shestopalov et al. (1991); Triggle et al. (1980); Wang et al. (1989).
Data collection: CAD-4 Software (Enraf-Nonius, 1989) for (I); P3 (Siemens, 1989) for (II). Cell refinement: CAD-4 Software for (I); P3 for (II). For both compounds, data reduction: SHELXTL-Plus (Sheldrick, 1994); program(s) used to solve structure: SHELXS97 (Sheldrick, 1990); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL-Plus; software used to prepare material for publication: SHELXL97.
C15H13N3O4 | F(000) = 312 |
Mr = 299.28 | Dx = 1.411 Mg m−3 |
Triclinic, P1 | Melting point: 492 K |
a = 8.1470 (16) Å | Mo Kα radiation, λ = 0.71073 Å |
b = 8.4120 (17) Å | Cell parameters from 24 reflections |
c = 11.149 (2) Å | θ = 11–12° |
α = 98.46 (3)° | µ = 0.11 mm−1 |
β = 108.69 (3)° | T = 298 K |
γ = 96.93 (3)° | Parallelepiped prism, colourless |
V = 704.3 (2) Å3 | 0.50 × 0.40 × 0.25 mm |
Z = 2 |
Enraf-Nonius CAD4 diffractometer | Rint = 0.017 |
Radiation source: fine-focus sealed tube | θmax = 27.0°, θmin = 2.0° |
Graphite monochromator | h = 0→10 |
θ/2θ scan | k = −10→10 |
3277 measured reflections | l = −14→13 |
3019 independent reflections | 3 standard reflections every 97 reflections |
1896 reflections with I > 2σ(I) | intensity decay: 3% |
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) = 0.169 | H-atom parameters constrained |
S = 1.02 | w = 1/[σ2(Fo2) + (0.1084P)2 + 0.037P] where P = (Fo2 + 2Fc2)/3 |
3019 reflections | (Δ/σ)max = 0.003 |
201 parameters | Δρmax = 0.22 e Å−3 |
0 restraints | Δρmin = −0.20 e Å−3 |
C15H13N3O4 | γ = 96.93 (3)° |
Mr = 299.28 | V = 704.3 (2) Å3 |
Triclinic, P1 | Z = 2 |
a = 8.1470 (16) Å | Mo Kα radiation |
b = 8.4120 (17) Å | µ = 0.11 mm−1 |
c = 11.149 (2) Å | T = 298 K |
α = 98.46 (3)° | 0.50 × 0.40 × 0.25 mm |
β = 108.69 (3)° |
Enraf-Nonius CAD4 diffractometer | Rint = 0.017 |
3277 measured reflections | 3 standard reflections every 97 reflections |
3019 independent reflections | intensity decay: 3% |
1896 reflections with I > 2σ(I) |
R[F2 > 2σ(F2)] = 0.055 | 0 restraints |
wR(F2) = 0.169 | H-atom parameters constrained |
S = 1.02 | Δρmax = 0.22 e Å−3 |
3019 reflections | Δρmin = −0.20 e Å−3 |
201 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. All H atoms were placed in geometrically calculated positions and refined using a riding model. |
x | y | z | Uiso*/Ueq | ||
O1 | 0.40336 (19) | 0.49394 (16) | 0.30002 (15) | 0.0341 (4) | |
O2 | 0.4262 (2) | 1.05888 (19) | 0.3402 (2) | 0.0539 (5) | |
O3 | 0.7438 (3) | 1.2880 (3) | 0.1398 (3) | 0.0749 (7) | |
O4 | 0.8359 (4) | 1.1941 (3) | −0.0112 (3) | 0.0914 (9) | |
N1 | 0.6282 (3) | 0.3812 (2) | 0.4021 (2) | 0.0413 (5) | |
H1A | 0.7365 | 0.3814 | 0.4457 | 0.050* | |
H1B | 0.5520 | 0.2924 | 0.3795 | 0.050* | |
N2 | 1.0069 (3) | 0.7102 (3) | 0.5306 (2) | 0.0523 (6) | |
N3 | 0.7720 (3) | 1.1754 (3) | 0.0712 (2) | 0.0506 (6) | |
C2 | 0.5783 (3) | 0.5187 (2) | 0.3696 (2) | 0.0286 (5) | |
C3 | 0.6797 (3) | 0.6685 (2) | 0.39678 (19) | 0.0279 (4) | |
C4 | 0.6050 (3) | 0.8074 (2) | 0.34073 (19) | 0.0254 (4) | |
H4A | 0.6570 | 0.9078 | 0.4063 | 0.030* | |
C5 | 0.4070 (3) | 0.7779 (2) | 0.31246 (19) | 0.0270 (4) | |
C6 | 0.3164 (3) | 0.6254 (2) | 0.2869 (2) | 0.0292 (5) | |
C7 | 0.1242 (3) | 0.5591 (3) | 0.2389 (3) | 0.0446 (6) | |
H7A | 0.0622 | 0.6266 | 0.1843 | 0.067* | |
H7B | 0.0839 | 0.5581 | 0.3108 | 0.067* | |
H7C | 0.1023 | 0.4498 | 0.1904 | 0.067* | |
C8 | 0.3291 (3) | 0.9282 (2) | 0.3171 (2) | 0.0316 (5) | |
C9 | 0.1404 (3) | 0.9291 (3) | 0.2999 (3) | 0.0476 (6) | |
H9A | 0.1209 | 1.0398 | 0.3106 | 0.071* | |
H9B | 0.1104 | 0.8774 | 0.3632 | 0.071* | |
H9C | 0.0681 | 0.8708 | 0.2149 | 0.071* | |
C10 | 0.6480 (3) | 0.8320 (2) | 0.2202 (2) | 0.0278 (5) | |
C11 | 0.6887 (3) | 0.9885 (3) | 0.1993 (2) | 0.0313 (5) | |
H11A | 0.6898 | 1.0793 | 0.2584 | 0.038* | |
C12 | 0.7275 (3) | 1.0080 (3) | 0.0906 (2) | 0.0381 (5) | |
C13 | 0.7290 (3) | 0.8787 (3) | −0.0005 (2) | 0.0477 (6) | |
H13A | 0.7561 | 0.8955 | −0.0732 | 0.057* | |
C14 | 0.6886 (4) | 0.7225 (3) | 0.0207 (3) | 0.0523 (7) | |
H14A | 0.6875 | 0.6323 | −0.0390 | 0.063* | |
C15 | 0.6500 (3) | 0.6998 (3) | 0.1292 (2) | 0.0391 (6) | |
H15A | 0.6248 | 0.5942 | 0.1421 | 0.047* | |
C16 | 0.8596 (3) | 0.6910 (2) | 0.4715 (2) | 0.0334 (5) |
U11 | U22 | U33 | U12 | U13 | U23 | |
O1 | 0.0332 (8) | 0.0151 (7) | 0.0487 (9) | 0.0005 (6) | 0.0109 (7) | −0.0001 (6) |
O2 | 0.0517 (11) | 0.0174 (8) | 0.0979 (15) | 0.0066 (7) | 0.0345 (10) | 0.0078 (8) |
O3 | 0.0943 (18) | 0.0408 (12) | 0.1029 (19) | 0.0090 (11) | 0.0474 (15) | 0.0275 (12) |
O4 | 0.132 (2) | 0.0741 (17) | 0.0867 (18) | −0.0079 (16) | 0.0658 (17) | 0.0323 (14) |
N1 | 0.0417 (11) | 0.0178 (9) | 0.0615 (14) | 0.0043 (7) | 0.0141 (10) | 0.0081 (8) |
N2 | 0.0354 (12) | 0.0430 (12) | 0.0676 (15) | 0.0082 (9) | 0.0048 (10) | 0.0061 (10) |
N3 | 0.0511 (13) | 0.0476 (13) | 0.0542 (13) | −0.0016 (10) | 0.0167 (11) | 0.0247 (11) |
C2 | 0.0334 (11) | 0.0174 (9) | 0.0356 (11) | 0.0050 (8) | 0.0134 (9) | 0.0032 (8) |
C3 | 0.0298 (11) | 0.0199 (9) | 0.0322 (11) | 0.0034 (8) | 0.0095 (8) | 0.0038 (8) |
C4 | 0.0271 (10) | 0.0145 (8) | 0.0320 (10) | 0.0010 (7) | 0.0092 (8) | 0.0013 (7) |
C5 | 0.0279 (10) | 0.0205 (9) | 0.0316 (10) | 0.0022 (8) | 0.0105 (8) | 0.0032 (7) |
C6 | 0.0312 (11) | 0.0204 (9) | 0.0346 (11) | 0.0050 (8) | 0.0114 (9) | 0.0008 (8) |
C7 | 0.0344 (12) | 0.0276 (11) | 0.0653 (17) | −0.0026 (9) | 0.0150 (11) | 0.0010 (11) |
C8 | 0.0386 (12) | 0.0214 (10) | 0.0373 (12) | 0.0064 (8) | 0.0161 (9) | 0.0061 (8) |
C9 | 0.0448 (14) | 0.0363 (13) | 0.0639 (17) | 0.0147 (11) | 0.0216 (12) | 0.0037 (12) |
C10 | 0.0254 (10) | 0.0219 (10) | 0.0324 (11) | 0.0015 (8) | 0.0077 (8) | 0.0013 (8) |
C11 | 0.0283 (10) | 0.0273 (10) | 0.0382 (12) | 0.0023 (8) | 0.0124 (9) | 0.0060 (9) |
C12 | 0.0296 (11) | 0.0413 (13) | 0.0416 (13) | 0.0019 (9) | 0.0091 (10) | 0.0133 (10) |
C13 | 0.0502 (15) | 0.0598 (17) | 0.0342 (13) | 0.0029 (12) | 0.0184 (11) | 0.0090 (11) |
C14 | 0.0619 (17) | 0.0465 (15) | 0.0429 (14) | 0.0011 (12) | 0.0214 (12) | −0.0093 (11) |
C15 | 0.0461 (13) | 0.0267 (11) | 0.0414 (13) | −0.0009 (9) | 0.0168 (11) | −0.0007 (9) |
C16 | 0.0386 (13) | 0.0193 (10) | 0.0415 (12) | 0.0064 (8) | 0.0134 (10) | 0.0034 (8) |
O1—C2 | 1.359 (3) | C6—C7 | 1.488 (3) |
O1—C6 | 1.384 (3) | C7—H7A | 0.9600 |
O2—C8 | 1.215 (3) | C7—H7B | 0.9600 |
O3—N3 | 1.219 (3) | C7—H7C | 0.9600 |
O4—N3 | 1.212 (3) | C8—C9 | 1.489 (3) |
N1—C2 | 1.333 (3) | C9—H9A | 0.9600 |
N1—H1A | 0.8600 | C9—H9B | 0.9600 |
N1—H1B | 0.8600 | C9—H9C | 0.9600 |
N2—C16 | 1.147 (3) | C10—C11 | 1.390 (3) |
N3—C12 | 1.476 (3) | C10—C15 | 1.396 (3) |
C2—C3 | 1.356 (3) | C11—C12 | 1.373 (3) |
C3—C16 | 1.408 (3) | C11—H11A | 0.9300 |
C3—C4 | 1.506 (3) | C12—C13 | 1.379 (4) |
C4—C5 | 1.523 (3) | C13—C14 | 1.389 (4) |
C4—C10 | 1.529 (3) | C13—H13A | 0.9300 |
C4—H4A | 0.9800 | C14—C15 | 1.377 (4) |
C5—C6 | 1.342 (3) | C14—H14A | 0.9300 |
C5—C8 | 1.483 (3) | C15—H15A | 0.9300 |
C2—O1—C6 | 120.10 (16) | H7B—C7—H7C | 109.5 |
C2—N1—H1A | 120.0 | O2—C8—C5 | 118.1 (2) |
C2—N1—H1B | 120.0 | O2—C8—C9 | 118.0 (2) |
H1A—N1—H1B | 120.0 | C5—C8—C9 | 123.93 (19) |
O4—N3—O3 | 123.4 (2) | C8—C9—H9A | 109.5 |
O4—N3—C12 | 118.5 (3) | C8—C9—H9B | 109.5 |
O3—N3—C12 | 118.1 (2) | H9A—C9—H9B | 109.5 |
N1—C2—C3 | 127.8 (2) | C8—C9—H9C | 109.5 |
N1—C2—O1 | 111.45 (17) | H9A—C9—H9C | 109.5 |
C3—C2—O1 | 120.70 (18) | H9B—C9—H9C | 109.5 |
C2—C3—C16 | 119.32 (19) | C11—C10—C15 | 118.0 (2) |
C2—C3—C4 | 120.76 (18) | C11—C10—C4 | 120.38 (18) |
C16—C3—C4 | 119.79 (17) | C15—C10—C4 | 121.60 (18) |
C3—C4—C5 | 108.92 (15) | C12—C11—C10 | 119.5 (2) |
C3—C4—C10 | 112.81 (17) | C12—C11—H11A | 120.3 |
C5—C4—C10 | 111.17 (17) | C10—C11—H11A | 120.3 |
C3—C4—H4A | 107.9 | C11—C12—C13 | 123.2 (2) |
C5—C4—H4A | 107.9 | C11—C12—N3 | 118.5 (2) |
C10—C4—H4A | 107.9 | C13—C12—N3 | 118.3 (2) |
C6—C5—C8 | 124.87 (19) | C12—C13—C14 | 117.2 (2) |
C6—C5—C4 | 120.45 (18) | C12—C13—H13A | 121.4 |
C8—C5—C4 | 114.67 (16) | C14—C13—H13A | 121.4 |
C5—C6—O1 | 120.62 (19) | C15—C14—C13 | 120.7 (2) |
C5—C6—C7 | 132.0 (2) | C15—C14—H14A | 119.7 |
O1—C6—C7 | 107.31 (17) | C13—C14—H14A | 119.7 |
C6—C7—H7A | 109.5 | C14—C15—C10 | 121.4 (2) |
C6—C7—H7B | 109.5 | C14—C15—H15A | 119.3 |
H7A—C7—H7B | 109.5 | C10—C15—H15A | 119.3 |
C6—C7—H7C | 109.5 | N2—C16—C3 | 178.8 (3) |
H7A—C7—H7C | 109.5 | ||
C6—O1—C2—N1 | 162.48 (19) | C4—C5—C8—O2 | 1.2 (3) |
C6—O1—C2—C3 | −18.1 (3) | C6—C5—C8—C9 | 3.0 (4) |
N1—C2—C3—C16 | −2.1 (4) | C4—C5—C8—C9 | −176.4 (2) |
O1—C2—C3—C16 | 178.58 (19) | C3—C4—C10—C11 | −141.52 (19) |
N1—C2—C3—C4 | 173.7 (2) | C5—C4—C10—C11 | 95.8 (2) |
O1—C2—C3—C4 | −5.6 (3) | C3—C4—C10—C15 | 37.6 (3) |
C2—C3—C4—C5 | 26.3 (3) | C5—C4—C10—C15 | −85.1 (2) |
C16—C3—C4—C5 | −157.87 (19) | C15—C10—C11—C12 | 0.7 (3) |
C2—C3—C4—C10 | −97.7 (2) | C4—C10—C11—C12 | 179.80 (19) |
C16—C3—C4—C10 | 78.2 (2) | C10—C11—C12—C13 | −0.3 (3) |
C3—C4—C5—C6 | −27.1 (3) | C10—C11—C12—N3 | −179.4 (2) |
C10—C4—C5—C6 | 97.8 (2) | O4—N3—C12—C11 | 167.1 (3) |
C3—C4—C5—C8 | 152.41 (17) | O3—N3—C12—C11 | −12.2 (4) |
C10—C4—C5—C8 | −82.7 (2) | O4—N3—C12—C13 | −12.1 (4) |
C8—C5—C6—O1 | −172.16 (19) | O3—N3—C12—C13 | 168.6 (3) |
C4—C5—C6—O1 | 7.3 (3) | C11—C12—C13—C14 | 0.2 (4) |
C8—C5—C6—C7 | 10.4 (4) | N3—C12—C13—C14 | 179.3 (2) |
C4—C5—C6—C7 | −170.1 (2) | C12—C13—C14—C15 | −0.4 (4) |
C2—O1—C6—C5 | 17.2 (3) | C13—C14—C15—C10 | 0.8 (4) |
C2—O1—C6—C7 | −164.83 (19) | C11—C10—C15—C14 | −0.9 (4) |
C6—C5—C8—O2 | −179.3 (2) | C4—C10—C15—C14 | 179.9 (2) |
C16H15N3O5 | F(000) = 344 |
Mr = 329.31 | Dx = 1.375 Mg m−3 |
Triclinic, P1 | Melting point: 457 K |
a = 8.455 (1) Å | Mo Kα radiation, λ = 0.71073 Å |
b = 8.475 (1) Å | Cell parameters from 24 reflections |
c = 12.073 (2) Å | θ = 11–12° |
α = 83.05 (2)° | µ = 0.10 mm−1 |
β = 71.33 (2)° | T = 298 K |
γ = 76.35 (2)° | Rhombohedral prism, colourless |
V = 795.46 (19) Å3 | 0.50 × 0.40 × 0.30 mm |
Z = 2 |
Siemens P3/PC diffractometer | Rint = 0.027 |
Radiation source: fine-focus sealed tube | θmax = 29.1°, θmin = 2.6° |
Graphite monochromator | h = 0→11 |
θ/2θ scan | k = −11→11 |
4216 measured reflections | l = −15→16 |
3942 independent reflections | 2 standard reflections every 98 reflections |
2553 reflections with I > 2σ(I) | intensity decay: 5% |
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)] = 0.058 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.154 | H-atom parameters constrained |
S = 1.03 | w = 1/[σ2(Fo2) + (0.0686P)2 + 0.1782P] where P = (Fo2 + 2Fc2)/3 |
3942 reflections | (Δ/σ)max = 0.003 |
219 parameters | Δρmax = 0.22 e Å−3 |
0 restraints | Δρmin = −0.20 e Å−3 |
C16H15N3O5 | γ = 76.35 (2)° |
Mr = 329.31 | V = 795.46 (19) Å3 |
Triclinic, P1 | Z = 2 |
a = 8.455 (1) Å | Mo Kα radiation |
b = 8.475 (1) Å | µ = 0.10 mm−1 |
c = 12.073 (2) Å | T = 298 K |
α = 83.05 (2)° | 0.50 × 0.40 × 0.30 mm |
β = 71.33 (2)° |
Siemens P3/PC diffractometer | Rint = 0.027 |
4216 measured reflections | 2 standard reflections every 98 reflections |
3942 independent reflections | intensity decay: 5% |
2553 reflections with I > 2σ(I) |
R[F2 > 2σ(F2)] = 0.058 | 0 restraints |
wR(F2) = 0.154 | H-atom parameters constrained |
S = 1.03 | Δρmax = 0.22 e Å−3 |
3942 reflections | Δρmin = −0.20 e Å−3 |
219 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. All H atoms were placed in geometrically calculated positions and refined using a riding model. |
x | y | z | Uiso*/Ueq | ||
O1 | 0.42683 (16) | 0.72685 (15) | 0.66604 (12) | 0.0474 (3) | |
O2 | 0.4589 (2) | 1.27563 (17) | 0.63437 (16) | 0.0653 (4) | |
O3 | 0.20256 (19) | 1.22029 (17) | 0.72605 (14) | 0.0617 (4) | |
O4 | 0.7001 (4) | 1.3820 (4) | 0.8855 (3) | 0.1289 (10) | |
O5 | 0.7751 (5) | 1.2557 (4) | 1.0301 (2) | 0.1713 (15) | |
N1 | 0.6440 (2) | 0.52577 (19) | 0.59401 (16) | 0.0534 (4) | |
H1A | 0.7498 | 0.4820 | 0.5632 | 0.064* | |
H1B | 0.5674 | 0.4684 | 0.6092 | 0.064* | |
N2 | 1.0204 (2) | 0.7037 (2) | 0.49837 (19) | 0.0650 (5) | |
N3 | 0.7329 (4) | 1.2585 (4) | 0.9430 (2) | 0.1010 (9) | |
C2 | 0.5988 (2) | 0.6821 (2) | 0.61807 (15) | 0.0405 (4) | |
C3 | 0.7002 (2) | 0.7906 (2) | 0.60051 (15) | 0.0391 (4) | |
C4 | 0.6320 (2) | 0.9550 (2) | 0.65293 (15) | 0.0370 (4) | |
H4A | 0.6862 | 1.0346 | 0.5968 | 0.044* | |
C5 | 0.4407 (2) | 1.0016 (2) | 0.67051 (15) | 0.0374 (4) | |
C6 | 0.3494 (2) | 0.8905 (2) | 0.67722 (15) | 0.0404 (4) | |
C7 | 0.1637 (3) | 0.9081 (3) | 0.6947 (2) | 0.0571 (5) | |
H7A | 0.1175 | 1.0161 | 0.6696 | 0.086* | |
H7B | 0.1062 | 0.8891 | 0.7762 | 0.086* | |
H7C | 0.1476 | 0.8305 | 0.6497 | 0.086* | |
C8 | 0.3702 (2) | 1.1780 (2) | 0.67468 (16) | 0.0436 (4) | |
C9 | 0.1247 (3) | 1.3945 (3) | 0.7246 (2) | 0.0677 (7) | |
H9A | 0.0098 | 1.4096 | 0.7197 | 0.081* | |
H9B | 0.1906 | 1.4493 | 0.6563 | 0.081* | |
C10 | 0.1194 (4) | 1.4657 (3) | 0.8315 (2) | 0.0858 (9) | |
H10A | 0.0566 | 1.5762 | 0.8340 | 0.129* | |
H10B | 0.2336 | 1.4632 | 0.8311 | 0.129* | |
H10C | 0.0644 | 1.4041 | 0.8990 | 0.129* | |
C11 | 0.6699 (2) | 0.9597 (2) | 0.76780 (15) | 0.0398 (4) | |
C12 | 0.6902 (3) | 1.1026 (3) | 0.80095 (17) | 0.0493 (5) | |
H12A | 0.6841 | 1.1964 | 0.7525 | 0.059* | |
C13 | 0.7194 (3) | 1.1041 (3) | 0.90676 (19) | 0.0625 (6) | |
C14 | 0.7329 (3) | 0.9690 (4) | 0.9805 (2) | 0.0727 (7) | |
H14A | 0.7548 | 0.9731 | 1.0507 | 0.087* | |
C15 | 0.7131 (3) | 0.8278 (4) | 0.9478 (2) | 0.0717 (7) | |
H15A | 0.7210 | 0.7343 | 0.9965 | 0.086* | |
C16 | 0.6812 (3) | 0.8224 (3) | 0.84249 (18) | 0.0554 (5) | |
H16A | 0.6673 | 0.7255 | 0.8218 | 0.066* | |
C17 | 0.8771 (2) | 0.7416 (2) | 0.54422 (17) | 0.0442 (4) |
U11 | U22 | U33 | U12 | U13 | U23 | |
O1 | 0.0398 (7) | 0.0349 (7) | 0.0630 (8) | −0.0114 (5) | −0.0052 (6) | −0.0068 (6) |
O2 | 0.0635 (10) | 0.0371 (7) | 0.1021 (13) | −0.0161 (7) | −0.0327 (9) | 0.0027 (8) |
O3 | 0.0559 (9) | 0.0413 (8) | 0.0753 (10) | 0.0017 (6) | −0.0083 (7) | −0.0104 (7) |
O4 | 0.198 (3) | 0.0984 (18) | 0.123 (2) | −0.0604 (19) | −0.064 (2) | −0.0315 (16) |
O5 | 0.276 (4) | 0.214 (3) | 0.0992 (18) | −0.140 (3) | −0.092 (2) | −0.0184 (19) |
N1 | 0.0470 (9) | 0.0359 (8) | 0.0727 (11) | −0.0103 (7) | −0.0079 (8) | −0.0105 (8) |
N2 | 0.0422 (10) | 0.0601 (11) | 0.0876 (14) | −0.0053 (8) | −0.0093 (9) | −0.0233 (10) |
N3 | 0.128 (2) | 0.133 (3) | 0.0690 (16) | −0.069 (2) | −0.0285 (15) | −0.0298 (16) |
C2 | 0.0426 (10) | 0.0358 (9) | 0.0411 (9) | −0.0082 (7) | −0.0089 (8) | −0.0048 (7) |
C3 | 0.0380 (9) | 0.0360 (9) | 0.0419 (9) | −0.0070 (7) | −0.0088 (7) | −0.0073 (7) |
C4 | 0.0401 (9) | 0.0342 (8) | 0.0377 (9) | −0.0110 (7) | −0.0102 (7) | −0.0034 (7) |
C5 | 0.0411 (9) | 0.0336 (9) | 0.0376 (9) | −0.0062 (7) | −0.0124 (7) | −0.0037 (7) |
C6 | 0.0406 (10) | 0.0361 (9) | 0.0425 (9) | −0.0076 (7) | −0.0092 (8) | −0.0042 (7) |
C7 | 0.0418 (11) | 0.0498 (11) | 0.0813 (15) | −0.0105 (9) | −0.0181 (10) | −0.0088 (10) |
C8 | 0.0506 (11) | 0.0357 (9) | 0.0487 (10) | −0.0069 (8) | −0.0217 (9) | −0.0033 (8) |
C9 | 0.0737 (15) | 0.0496 (12) | 0.0681 (14) | 0.0093 (11) | −0.0203 (12) | −0.0059 (11) |
C10 | 0.117 (2) | 0.0602 (15) | 0.0746 (17) | 0.0012 (15) | −0.0317 (16) | −0.0152 (13) |
C11 | 0.0328 (9) | 0.0465 (10) | 0.0387 (9) | −0.0064 (7) | −0.0084 (7) | −0.0067 (8) |
C12 | 0.0489 (11) | 0.0583 (12) | 0.0453 (10) | −0.0187 (9) | −0.0131 (8) | −0.0087 (9) |
C13 | 0.0591 (13) | 0.0883 (17) | 0.0499 (12) | −0.0277 (12) | −0.0164 (10) | −0.0171 (12) |
C14 | 0.0592 (14) | 0.119 (2) | 0.0437 (12) | −0.0168 (14) | −0.0204 (10) | −0.0095 (14) |
C15 | 0.0726 (16) | 0.0856 (18) | 0.0501 (13) | −0.0029 (13) | −0.0241 (12) | 0.0108 (12) |
C16 | 0.0590 (13) | 0.0558 (12) | 0.0486 (11) | −0.0054 (10) | −0.0184 (10) | 0.0006 (9) |
C17 | 0.0439 (11) | 0.0376 (9) | 0.0533 (11) | −0.0083 (8) | −0.0149 (9) | −0.0105 (8) |
O1—C2 | 1.359 (2) | C6—C7 | 1.489 (3) |
O1—C6 | 1.389 (2) | C7—H7A | 0.9600 |
O2—C8 | 1.203 (2) | C7—H7B | 0.9600 |
O3—C8 | 1.331 (2) | C7—H7C | 0.9600 |
O3—C9 | 1.468 (3) | C9—C10 | 1.473 (4) |
O4—N3 | 1.209 (3) | C9—H9A | 0.9700 |
O5—N3 | 1.211 (3) | C9—H9B | 0.9700 |
N1—C2 | 1.330 (2) | C10—H10A | 0.9600 |
N1—H1A | 0.8600 | C10—H10B | 0.9600 |
N1—H1B | 0.8600 | C10—H10C | 0.9600 |
N2—C17 | 1.143 (2) | C11—C12 | 1.384 (3) |
N3—C13 | 1.469 (4) | C11—C16 | 1.388 (3) |
C2—C3 | 1.355 (2) | C12—C13 | 1.379 (3) |
C3—C17 | 1.413 (3) | C12—H12A | 0.9300 |
C3—C4 | 1.508 (2) | C13—C14 | 1.369 (4) |
C4—C5 | 1.522 (2) | C14—C15 | 1.367 (4) |
C4—C11 | 1.527 (2) | C14—H14A | 0.9300 |
C4—H4A | 0.9800 | C15—C16 | 1.389 (3) |
C5—C6 | 1.333 (2) | C15—H15A | 0.9300 |
C5—C8 | 1.473 (2) | C16—H16A | 0.9300 |
C2—O1—C6 | 119.90 (14) | O2—C8—C5 | 121.83 (18) |
C8—O3—C9 | 117.04 (18) | O3—C8—C5 | 115.19 (16) |
C2—N1—H1A | 120.0 | O3—C9—C10 | 110.2 (2) |
C2—N1—H1B | 120.0 | O3—C9—H9A | 109.6 |
H1A—N1—H1B | 120.0 | C10—C9—H9A | 109.6 |
O4—N3—O5 | 123.2 (3) | O3—C9—H9B | 109.6 |
O4—N3—C13 | 118.9 (2) | C10—C9—H9B | 109.6 |
O5—N3—C13 | 117.9 (3) | H9A—C9—H9B | 108.1 |
N1—C2—C3 | 128.39 (17) | C9—C10—H10A | 109.5 |
N1—C2—O1 | 110.66 (15) | C9—C10—H10B | 109.5 |
C3—C2—O1 | 120.95 (15) | H10A—C10—H10B | 109.5 |
C2—C3—C17 | 119.14 (16) | C9—C10—H10C | 109.5 |
C2—C3—C4 | 121.16 (16) | H10A—C10—H10C | 109.5 |
C17—C3—C4 | 119.26 (15) | H10B—C10—H10C | 109.5 |
C3—C4—C5 | 108.60 (14) | C12—C11—C16 | 118.43 (18) |
C3—C4—C11 | 112.88 (14) | C12—C11—C4 | 120.56 (17) |
C5—C4—C11 | 110.71 (14) | C16—C11—C4 | 121.00 (17) |
C3—C4—H4A | 108.2 | C13—C12—C11 | 119.2 (2) |
C5—C4—H4A | 108.2 | C13—C12—H12A | 120.4 |
C11—C4—H4A | 108.2 | C11—C12—H12A | 120.4 |
C6—C5—C8 | 124.14 (17) | C14—C13—C12 | 122.9 (2) |
C6—C5—C4 | 121.73 (15) | C14—C13—N3 | 118.6 (2) |
C8—C5—C4 | 114.09 (15) | C12—C13—N3 | 118.4 (3) |
C5—C6—O1 | 120.82 (16) | C15—C14—C13 | 117.9 (2) |
C5—C6—C7 | 130.77 (17) | C15—C14—H14A | 121.0 |
O1—C6—C7 | 108.40 (15) | C13—C14—H14A | 121.0 |
C6—C7—H7A | 109.5 | C14—C15—C16 | 120.7 (2) |
C6—C7—H7B | 109.5 | C14—C15—H15A | 119.7 |
H7A—C7—H7B | 109.5 | C16—C15—H15A | 119.7 |
C6—C7—H7C | 109.5 | C11—C16—C15 | 120.9 (2) |
H7A—C7—H7C | 109.5 | C11—C16—H16A | 119.6 |
H7B—C7—H7C | 109.5 | C15—C16—H16A | 119.6 |
O2—C8—O3 | 122.97 (17) | N2—C17—C3 | 179.2 (2) |
C6—O1—C2—N1 | −167.79 (16) | C4—C5—C8—O2 | 20.6 (3) |
C6—O1—C2—C3 | 12.2 (3) | C6—C5—C8—O3 | 22.9 (3) |
N1—C2—C3—C17 | 3.7 (3) | C4—C5—C8—O3 | −159.31 (15) |
O1—C2—C3—C17 | −176.35 (17) | C8—O3—C9—C10 | −92.6 (3) |
N1—C2—C3—C4 | −168.61 (18) | C3—C4—C11—C12 | 150.52 (17) |
O1—C2—C3—C4 | 11.4 (3) | C5—C4—C11—C12 | −87.5 (2) |
C2—C3—C4—C5 | −26.4 (2) | C3—C4—C11—C16 | −30.8 (2) |
C17—C3—C4—C5 | 161.32 (16) | C5—C4—C11—C16 | 91.1 (2) |
C2—C3—C4—C11 | 96.7 (2) | C16—C11—C12—C13 | −0.5 (3) |
C17—C3—C4—C11 | −75.5 (2) | C4—C11—C12—C13 | 178.17 (17) |
C3—C4—C5—C6 | 21.4 (2) | C11—C12—C13—C14 | 1.3 (3) |
C11—C4—C5—C6 | −103.05 (19) | C11—C12—C13—N3 | −177.3 (2) |
C3—C4—C5—C8 | −156.43 (15) | O4—N3—C13—C14 | −170.9 (3) |
C11—C4—C5—C8 | 79.12 (18) | O5—N3—C13—C14 | 8.5 (4) |
C8—C5—C6—O1 | 176.34 (16) | O4—N3—C13—C12 | 7.7 (4) |
C4—C5—C6—O1 | −1.3 (3) | O5—N3—C13—C12 | −172.9 (3) |
C8—C5—C6—C7 | −2.9 (3) | C12—C13—C14—C15 | −1.2 (4) |
C4—C5—C6—C7 | 179.53 (19) | N3—C13—C14—C15 | 177.3 (2) |
C2—O1—C6—C5 | −17.4 (3) | C13—C14—C15—C16 | 0.3 (4) |
C2—O1—C6—C7 | 161.94 (17) | C12—C11—C16—C15 | −0.3 (3) |
C9—O3—C8—O2 | 4.4 (3) | C4—C11—C16—C15 | −179.01 (19) |
C9—O3—C8—C5 | −175.67 (17) | C14—C15—C16—C11 | 0.4 (4) |
C6—C5—C8—O2 | −157.15 (19) |
D—H···A | D—H | H···A | D···A | D—H···A |
N1—H1B···O2i | 0.86 | 2.00 | 2.830 (2) | 161 |
N1—H1A···N2ii | 0.86 | 2.17 | 2.995 (2) | 160 |
Symmetry codes: (i) x, y−1, z; (ii) −x+2, −y+1, −z+1. |
Experimental details
(I) | (II) | |
Crystal data | ||
Chemical formula | C15H13N3O4 | C16H15N3O5 |
Mr | 299.28 | 329.31 |
Crystal system, space group | Triclinic, P1 | Triclinic, P1 |
Temperature (K) | 298 | 298 |
a, b, c (Å) | 8.1470 (16), 8.4120 (17), 11.149 (2) | 8.455 (1), 8.475 (1), 12.073 (2) |
α, β, γ (°) | 98.46 (3), 108.69 (3), 96.93 (3) | 83.05 (2), 71.33 (2), 76.35 (2) |
V (Å3) | 704.3 (2) | 795.46 (19) |
Z | 2 | 2 |
Radiation type | Mo Kα | Mo Kα |
µ (mm−1) | 0.11 | 0.10 |
Crystal size (mm) | 0.50 × 0.40 × 0.25 | 0.50 × 0.40 × 0.30 |
Data collection | ||
Diffractometer | Enraf-Nonius CAD4 | Siemens P3/PC |
Absorption correction | – | – |
No. of measured, independent and observed [I > 2σ(I)] reflections | 3277, 3019, 1896 | 4216, 3942, 2553 |
Rint | 0.017 | 0.027 |
(sin θ/λ)max (Å−1) | 0.638 | 0.683 |
Refinement | ||
R[F2 > 2σ(F2)], wR(F2), S | 0.055, 0.169, 1.02 | 0.058, 0.154, 1.03 |
No. of reflections | 3019 | 3942 |
No. of parameters | 201 | 219 |
H-atom treatment | H-atom parameters constrained | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.22, −0.20 | 0.22, −0.20 |
Computer programs: CAD-4 Software (Enraf-Nonius, 1989), P3 (Siemens, 1989), CAD-4 Software, P3, SHELXTL-Plus (Sheldrick, 1994), SHELXS97 (Sheldrick, 1990), SHELXL97 (Sheldrick, 1997), SHELXTL-Plus, SHELXL97.
O2—C8 | 1.215 (3) | C3—C16 | 1.408 (3) |
N1—C2 | 1.333 (3) | C5—C6 | 1.342 (3) |
N2—C16 | 1.147 (3) | C5—C8 | 1.483 (3) |
C2—C3 | 1.356 (3) | ||
N1—C2—C3 | 127.8 (2) | C6—C5—C4 | 120.45 (18) |
N1—C2—O1 | 111.45 (17) | C8—C5—C4 | 114.67 (16) |
C3—C2—O1 | 120.70 (18) | C5—C6—O1 | 120.62 (19) |
C2—C3—C16 | 119.32 (19) | C5—C6—C7 | 132.0 (2) |
C2—C3—C4 | 120.76 (18) | O1—C6—C7 | 107.31 (17) |
C16—C3—C4 | 119.79 (17) | N2—C16—C3 | 178.8 (3) |
C6—C5—C8 | 124.87 (19) | ||
O1—C2—C3—C4 | −5.6 (3) | C4—C5—C6—O1 | 7.3 (3) |
C2—C3—C4—C10 | −97.7 (2) | C6—C5—C8—O2 | −179.3 (2) |
O2—C8 | 1.203 (2) | C3—C17 | 1.413 (3) |
N1—C2 | 1.330 (2) | C5—C6 | 1.333 (2) |
N2—C17 | 1.143 (2) | C5—C8 | 1.473 (2) |
C2—C3 | 1.355 (2) | ||
N1—C2—C3 | 128.39 (17) | C6—C5—C4 | 121.73 (15) |
N1—C2—O1 | 110.66 (15) | C8—C5—C4 | 114.09 (15) |
C3—C2—O1 | 120.95 (15) | C5—C6—O1 | 120.82 (16) |
C2—C3—C17 | 119.14 (16) | C5—C6—C7 | 130.77 (17) |
C2—C3—C4 | 121.16 (16) | O1—C6—C7 | 108.40 (15) |
C17—C3—C4 | 119.26 (15) | N2—C17—C3 | 179.2 (2) |
C6—C5—C8 | 124.14 (17) | ||
O1—C2—C3—C4 | 11.4 (3) | C6—C5—C8—O2 | −157.15 (19) |
C2—C3—C4—C11 | 96.7 (2) | C8—O3—C9—C10 | −92.6 (3) |
C4—C5—C6—O1 | −1.3 (3) |
D—H···A | D—H | H···A | D···A | D—H···A |
N1—H1B···O2i | 0.86 | 2.00 | 2.830 (2) | 161 |
N1—H1A···N2ii | 0.86 | 2.17 | 2.995 (2) | 160 |
Symmetry codes: (i) x, y−1, z; (ii) −x+2, −y+1, −z+1. |
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The synthesis of hydrogenated compounds has been extensively studied, due to their biological properties. For example, derivatives of 1,4-dihydropyridine exhibit high biological activities as calcium channel blockers (Bossert et al., 1981) and as calcium agonists or antagonists (Triggle et al., 1980; Kokubun & Reuter, 1984; Bossert & Vater, 1989; Wang et al., 1989; Alajarin et al., 1995). 4H-Pyran derivatives have structures similar to those of 1,4-dihydropyridine and elicit the interest of organic chemists as well as of crystallographers. Many different methods have been proposed for the synthesis of 4H-pyran derivatives, for example by Junek & Aigner (1970) and Rappoport & Ladkani (1974). Structural studies of some derivatives of 4H-pyrans by X-ray analysis have been published (Florencio & Garcia-Blanco, 1987; Bellanato et al., 1987, 1988; Lokai et al., 1990; Marco et al., 1993). The present study represents a continuation of our investigations of the structures of 4H-pyran derivatives (Sharanina et al., 1986; Klokol et al., 1987; Shestopalov et al., 1991; Samet et al., 1996; Kislyi et al., 1999a,b). The crystal structures of 5-acetyl-2-amino-6-methyl-4-(3-nitrophenyl)-4H-pyran-3-carbonitrile, (I), and ethyl 6-amino-5-cyano-2-methyl-4-(3-nitrophenyl)-4H-pyrano-3-carboxylate, (II), are presented herein. \sch
The pyran rings in both molecules have boat conformations, with atoms O1 and C4 out of the C2/C3/C5/C6 plane by -0.179 (1) and -0.341 (1) Å, respectively, in (I), and by 0.151 (2) and 0.306 (2) Å, respectively, in (II). The C2/C3/C5/C6 plane is planar to within 0.005 (1) Å for (I) and 0.026 (1) Å for (II). The bending of the ring along O1···C4, C2···C6 and C3···C5 equals 24.0 (1), 15.1 (1) and 22.8 (2)°, respectively, in (I), and 21.2 (1), 12.7 (1) and 20.3 (2)°, respectively, in (II). The heterocycles in (I) and (II), in pyrans with comparable structures, and in derivatives of 1,4-dihydropyridine, for example, nifedipine (Triggle et al., 1980), nimodipine (Wang et al., 1989) and furnidipine (Alajarin et al., 1995), have similar conformations.
The dihedral angle between the pseudo-axial aryl substituent and the C2/C3/C5/C6 plane of the boat of the heterocycle is 84.0 (1)° in (I) and 98.7 (1)° in (II), minimizing possible intramolecular sterical contacts in both molecules. Similar orientations of sterically demanding substituents were found in all previously determined derivatives of 4H-pyrans (Sharanina et al., 1986; Klokol et al., 1987; Shestopalov et al., 1991; Samet et al., 1996; Kislyi et al., 1999a,b; Florencio & Garcia-Blanco, 1987; Bellanato et al., 1988; Lokai et al., 1990; Marco et al., 1993). The value of the angle is close to 90° in practically all known 4H-pyran derivatives containing sterically demanding substituents in the 4-position of the heterocycle.
The nitro groups are slightly rotated from the plane of the phenyl ring of the aryl substituent, by 12.1 (2)° in (I) and 8.4 (2)° in (II). As shown in Figs. 1 and 2, the substituents at C5 of the heterocycle have trans orientations with respect to the C5═C6 double bond. The C6—C5—C8—O2 torsion angle is -179.3 (2)° in (I) and -157.2 (2)° in (II). It is interesting to note that the acetyl substituent has a cis geometry in the 1,4-dihydropyridine derivative described by Nesterov et al. (1985), and ester groups have cis geometry in substituted 4H-pyrans and form intramolecular hydrogen bonds with amino groups (Sharanina et al., 1986; Klokol et al., 1987; Shestopalov et al., 1991).
The bond lengths in the planar fragment N1—C2═C3—C16/C17≡N2 in both structures are different from typical literature values (Allen et al., 1987). This bond length distribution was observed in all derivatives of 4H-pyrans that we investigated and has also been noted in the literature (Samet et al., 1996; Bellanato et al., 1987; Lokai et al., 1990; Marco et al., 1993). This regularity can be explained by the conjugation of bonds in the fragment. However, in the C6═ C5—C8═O2 fragment, located on the opposite side of the pyran ring in both compounds, the bond lengths agree with standard values (Allen et al., 1987) and this confirms the absence of conjugation in this fragment of both molecules. The mutual orientation of substituents of the pyran ring in both molecules gives rise to an intramolecular O2···H4A non-bonded interaction. The length of this interaction is 2.38 Å in (I) and 2.43 Å in (II), less than the sum of the relevant van der Waals radii (Rowlend & Taylor, 1996). The rest of the geometrical parameters in (I) and (II) have standard values (Allen et al., 1987).
The structures of (I) and (II) both exhibit intermolecular N1—H1B···O2(x, y - 1, z) and N1—H1A···N2(2 - x, 1 - y, 1 - z) hydrogen bonds, which connect molecules into infinite tapes along the b axis.