Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270100017960/sk1429sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S0108270100017960/sk1429Isup2.hkl |
CCDC reference: 160008
Compound (I) was prepared by a procedure similar to one described by Jefferson & Warkentin (1992) for other compounds. (1R,4R)-Camphoracetylhydrazone (500 mg, 2.40 mmol) (Somogyi, 1991) and lead tetraacetate (1.06 g, 2.40 mmol) in absolute methanol (6.5 ml) afforded 5-methoxy-1',5,7',7'- tetramethylspiro{Δ3-1,3,4-oxadiazolin-(1'R,4'R)-2,2'-bicyclo[2.2.1]heptane} (250 mg, 43%) as a mixture of four diastereomers that were used without separation. A solution of the latter oxadiazolin (230 mg, 965 µmol) and dimethyl acetylenedicarboxylate (411 mg, 2.89 mmol) in diethylether (55 ml) was irradiated with a medium pressure mercury lamp at room temperature for 8 h. After the volatiles had been removed in vacuo, column chromatography (silica gel, hexane/ethyl acetate = 10:1) provided 210 mg (71%) of the title compound (I). Single crystals were obtained by slow evaporation of a solution in pentane/dichloromethane at 273 K.
A 0.8 mm collimator was used. Friedel opposites were averaged. The H atoms were taken from a difference Fourier synthesis. They were refined with fixed individual thermal parameters [U(H) = 1.2Ueq(C) and U(H) = 1.5Ueq(Cmethyl)] using a riding model with fixed distances: H—C(methyl) = 0.98 Å, H—C(secondary) = 0.99 Å and H—C(primary) = 1.00 Å, respectively. Torsion angles about the C—C or C—O bonds of the methyl groups were refined.
Data collection: SMART (Siemens, 1995); cell refinement: SMART; data reduction: SAINT (Siemens, 1995); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: XP in SHELXTL (Sheldrick, 1996); software used to prepare material for publication: CIF in SHELXL97 (Sheldrick, 1997).
C16H22N2O4 | F(000) = 656 |
Mr = 306.36 | Dx = 1.315 Mg m−3 |
Monoclinic, P21 | Mo Kα radiation, λ = 0.71073 Å |
a = 7.3772 (14) Å | Cell parameters from 188 reflections |
b = 20.063 (3) Å | θ = 3–23° |
c = 10.4576 (12) Å | µ = 0.10 mm−1 |
β = 90.513 (12)° | T = 143 K |
V = 1547.7 (4) Å3 | Block, colorless |
Z = 4 | 0.70 × 0.40 × 0.36 mm |
SIEMENS SMART diffractometer | 4858 independent reflections |
Radiation source: normal-focus sealed tube | 4589 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.029 |
ω scans | θmax = 31.0°, θmin = 2.0° |
Absorption correction: numerical six indexed faces (SHELXTL; Sheldrick, 1996) | h = −10→10 |
Tmin = 0.943, Tmax = 0.969 | k = −28→29 |
30858 measured reflections | l = −14→15 |
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)] = 0.036 | Hydrogen site location: difference Fourier map |
wR(F2) = 0.096 | H-atom parameters constrained |
S = 1.08 | w = 1/[σ2(Fo2) + (0.055P)2 + 0.28P] where P = (Fo2 + 2Fc2)/3 |
4858 reflections | (Δ/σ)max = 0.001 |
407 parameters | Δρmax = 0.44 e Å−3 |
1 restraint | Δρmin = −0.30 e Å−3 |
C16H22N2O4 | V = 1547.7 (4) Å3 |
Mr = 306.36 | Z = 4 |
Monoclinic, P21 | Mo Kα radiation |
a = 7.3772 (14) Å | µ = 0.10 mm−1 |
b = 20.063 (3) Å | T = 143 K |
c = 10.4576 (12) Å | 0.70 × 0.40 × 0.36 mm |
β = 90.513 (12)° |
SIEMENS SMART diffractometer | 4858 independent reflections |
Absorption correction: numerical six indexed faces (SHELXTL; Sheldrick, 1996) | 4589 reflections with I > 2σ(I) |
Tmin = 0.943, Tmax = 0.969 | Rint = 0.029 |
30858 measured reflections |
R[F2 > 2σ(F2)] = 0.036 | 1 restraint |
wR(F2) = 0.096 | H-atom parameters constrained |
S = 1.08 | Δρmax = 0.44 e Å−3 |
4858 reflections | Δρmin = −0.30 e Å−3 |
407 parameters |
Experimental. A 0.8 mm colimator was used. |
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 | 0.88181 (18) | 0.33711 (8) | 0.10555 (12) | 0.0296 (3) | |
O2 | 0.6803 (3) | 0.29414 (15) | 0.23891 (17) | 0.0704 (8) | |
O3 | 0.81218 (17) | 0.52951 (6) | 0.39547 (12) | 0.0233 (2) | |
O4 | 0.71229 (18) | 0.46974 (8) | 0.22663 (13) | 0.0277 (3) | |
O5 | 0.11490 (17) | 0.66123 (8) | 0.39238 (12) | 0.0281 (3) | |
O6 | 0.3064 (2) | 0.70926 (9) | 0.25519 (13) | 0.0362 (4) | |
O7 | 0.17807 (17) | 0.47207 (6) | 0.09718 (12) | 0.0221 (2) | |
O8 | 0.28172 (17) | 0.53138 (7) | 0.26597 (12) | 0.0253 (3) | |
N1 | 1.11683 (19) | 0.36006 (7) | 0.47739 (13) | 0.0178 (3) | |
N2 | 1.0437 (2) | 0.31789 (7) | 0.38873 (14) | 0.0195 (3) | |
N3 | −0.13818 (18) | 0.64008 (7) | 0.02556 (13) | 0.0176 (3) | |
N4 | −0.06488 (19) | 0.68205 (7) | 0.11495 (14) | 0.0196 (3) | |
C1 | 0.9274 (2) | 0.35580 (9) | 0.32344 (16) | 0.0189 (3) | |
C2 | 0.9225 (2) | 0.42190 (8) | 0.37032 (15) | 0.0181 (3) | |
C3 | 1.0463 (2) | 0.42206 (8) | 0.47179 (15) | 0.0175 (3) | |
C4 | 1.1072 (2) | 0.47450 (8) | 0.56464 (16) | 0.0212 (3) | |
H4A | 1.0007 | 0.4990 | 0.5973 | 0.025* | |
H4B | 1.1872 | 0.5068 | 0.5210 | 0.025* | |
C5 | 1.2099 (2) | 0.44188 (8) | 0.67630 (15) | 0.0202 (3) | |
H5 | 1.2662 | 0.4766 | 0.7326 | 0.024* | |
C6 | 1.0818 (3) | 0.39642 (9) | 0.75462 (16) | 0.0251 (3) | |
H6A | 1.1167 | 0.3969 | 0.8463 | 0.030* | |
H6B | 0.9547 | 0.4118 | 0.7462 | 0.030* | |
C7 | 1.1030 (2) | 0.32536 (9) | 0.69831 (17) | 0.0234 (3) | |
H7A | 1.1560 | 0.2946 | 0.7625 | 0.028* | |
H7B | 0.9843 | 0.3075 | 0.6695 | 0.028* | |
C8 | 1.2319 (2) | 0.33439 (8) | 0.58401 (15) | 0.0188 (3) | |
C9 | 1.3258 (3) | 0.27105 (9) | 0.5420 (2) | 0.0284 (4) | |
H9A | 1.4021 | 0.2542 | 0.6120 | 0.043* | |
H9B | 1.4013 | 0.2805 | 0.4675 | 0.043* | |
H9C | 1.2346 | 0.2375 | 0.5192 | 0.043* | |
C10 | 1.3557 (2) | 0.39303 (8) | 0.62697 (16) | 0.0204 (3) | |
C11 | 1.4797 (3) | 0.37109 (10) | 0.73899 (19) | 0.0280 (4) | |
H11A | 1.5644 | 0.3369 | 0.7092 | 0.042* | |
H11B | 1.4055 | 0.3528 | 0.8079 | 0.042* | |
H11C | 1.5480 | 0.4096 | 0.7710 | 0.042* | |
C12 | 1.4749 (3) | 0.42088 (11) | 0.52069 (19) | 0.0297 (4) | |
H12A | 1.3990 | 0.4328 | 0.4468 | 0.045* | |
H12B | 1.5636 | 0.3871 | 0.4954 | 0.045* | |
H12C | 1.5387 | 0.4606 | 0.5518 | 0.045* | |
C13 | 0.8149 (2) | 0.32522 (10) | 0.21954 (17) | 0.0242 (3) | |
C14 | 0.7784 (3) | 0.31090 (14) | −0.00154 (19) | 0.0360 (5) | |
H14A | 0.7670 | 0.2625 | 0.0072 | 0.054* | |
H14B | 0.8407 | 0.3214 | −0.0814 | 0.054* | |
H14C | 0.6575 | 0.3311 | −0.0028 | 0.054* | |
C15 | 0.8055 (2) | 0.47500 (9) | 0.32170 (16) | 0.0201 (3) | |
C16 | 0.6950 (2) | 0.58352 (9) | 0.35556 (19) | 0.0256 (3) | |
H16A | 0.7088 | 0.6210 | 0.4150 | 0.038* | |
H16B | 0.5688 | 0.5683 | 0.3553 | 0.038* | |
H16C | 0.7281 | 0.5979 | 0.2693 | 0.038* | |
C17 | 0.0588 (2) | 0.64506 (8) | 0.17458 (15) | 0.0177 (3) | |
C18 | 0.0666 (2) | 0.57964 (8) | 0.12528 (16) | 0.0172 (3) | |
C19 | −0.0649 (2) | 0.57862 (8) | 0.02850 (15) | 0.0165 (3) | |
C20 | −0.1272 (2) | 0.52661 (8) | −0.06404 (16) | 0.0200 (3) | |
H20A | −0.1537 | 0.4848 | −0.0177 | 0.024* | |
H20B | −0.0301 | 0.5174 | −0.1264 | 0.024* | |
C21 | −0.2979 (2) | 0.55042 (8) | −0.13485 (15) | 0.0205 (3) | |
H21 | −0.3280 | 0.5197 | −0.2073 | 0.025* | |
C22 | −0.4595 (2) | 0.55542 (10) | −0.04149 (18) | 0.0260 (3) | |
H22A | −0.5742 | 0.5430 | −0.0853 | 0.031* | |
H22B | −0.4409 | 0.5254 | 0.0326 | 0.031* | |
C23 | −0.4658 (2) | 0.62900 (10) | 0.00278 (16) | 0.0246 (3) | |
H23A | −0.5772 | 0.6512 | −0.0291 | 0.030* | |
H23B | −0.4622 | 0.6320 | 0.0973 | 0.030* | |
C24 | −0.2961 (2) | 0.66110 (8) | −0.05540 (15) | 0.0184 (3) | |
C25 | −0.3015 (3) | 0.73665 (9) | −0.06424 (19) | 0.0275 (4) | |
H25A | −0.4003 | 0.7502 | −0.1219 | 0.041* | |
H25B | −0.1860 | 0.7530 | −0.0975 | 0.041* | |
H25C | −0.3218 | 0.7555 | 0.0209 | 0.041* | |
C26 | −0.2758 (2) | 0.62291 (8) | −0.18384 (15) | 0.0190 (3) | |
C27 | −0.4328 (3) | 0.63938 (10) | −0.27623 (17) | 0.0286 (4) | |
H27A | −0.4278 | 0.6867 | −0.2994 | 0.043* | |
H27B | −0.5485 | 0.6299 | −0.2346 | 0.043* | |
H27C | −0.4223 | 0.6121 | −0.3535 | 0.043* | |
C28 | −0.0981 (3) | 0.63737 (10) | −0.25246 (17) | 0.0281 (4) | |
H28A | −0.0985 | 0.6835 | −0.2832 | 0.042* | |
H28B | −0.0856 | 0.6070 | −0.3252 | 0.042* | |
H28C | 0.0038 | 0.6309 | −0.1930 | 0.042* | |
C29 | 0.1754 (2) | 0.67532 (8) | 0.27676 (16) | 0.0194 (3) | |
C30 | 0.2285 (3) | 0.68466 (13) | 0.49677 (18) | 0.0349 (5) | |
H30A | 0.3537 | 0.6702 | 0.4830 | 0.052* | |
H30B | 0.1847 | 0.6662 | 0.5775 | 0.052* | |
H30C | 0.2239 | 0.7334 | 0.5004 | 0.052* | |
C31 | 0.1866 (2) | 0.52672 (8) | 0.17170 (15) | 0.0176 (3) | |
C32 | 0.2928 (2) | 0.41720 (9) | 0.13646 (19) | 0.0247 (3) | |
H32A | 0.4188 | 0.4324 | 0.1426 | 0.037* | |
H32B | 0.2836 | 0.3812 | 0.0734 | 0.037* | |
H32C | 0.2536 | 0.4008 | 0.2200 | 0.037* |
U11 | U22 | U33 | U12 | U13 | U23 | |
O1 | 0.0250 (6) | 0.0453 (8) | 0.0186 (6) | −0.0110 (6) | 0.0002 (5) | −0.0071 (6) |
O2 | 0.0664 (13) | 0.117 (2) | 0.0275 (8) | −0.0665 (14) | −0.0082 (8) | 0.0059 (10) |
O3 | 0.0253 (6) | 0.0182 (5) | 0.0264 (6) | 0.0021 (5) | −0.0065 (5) | 0.0039 (5) |
O4 | 0.0262 (6) | 0.0348 (7) | 0.0220 (6) | 0.0056 (5) | −0.0071 (5) | 0.0014 (5) |
O5 | 0.0216 (6) | 0.0437 (8) | 0.0190 (6) | −0.0081 (6) | −0.0023 (4) | −0.0035 (6) |
O6 | 0.0355 (7) | 0.0477 (9) | 0.0253 (7) | −0.0227 (7) | −0.0046 (5) | −0.0003 (6) |
O7 | 0.0235 (6) | 0.0152 (5) | 0.0274 (6) | 0.0031 (4) | −0.0055 (4) | −0.0003 (5) |
O8 | 0.0230 (6) | 0.0255 (6) | 0.0273 (6) | 0.0044 (5) | −0.0073 (5) | −0.0018 (5) |
N1 | 0.0210 (6) | 0.0149 (6) | 0.0174 (6) | 0.0005 (5) | −0.0045 (5) | −0.0020 (5) |
N2 | 0.0224 (6) | 0.0174 (6) | 0.0188 (6) | −0.0011 (5) | −0.0038 (5) | −0.0027 (5) |
N3 | 0.0198 (6) | 0.0138 (6) | 0.0191 (6) | 0.0005 (5) | −0.0046 (5) | −0.0020 (5) |
N4 | 0.0210 (6) | 0.0170 (6) | 0.0205 (6) | 0.0002 (5) | −0.0051 (5) | −0.0047 (5) |
C1 | 0.0187 (7) | 0.0207 (7) | 0.0174 (7) | −0.0031 (6) | −0.0011 (5) | 0.0002 (6) |
C2 | 0.0173 (7) | 0.0194 (7) | 0.0177 (7) | −0.0002 (6) | −0.0013 (5) | 0.0026 (6) |
C3 | 0.0192 (7) | 0.0161 (6) | 0.0172 (7) | 0.0004 (5) | −0.0003 (5) | 0.0014 (5) |
C4 | 0.0275 (8) | 0.0151 (7) | 0.0210 (7) | 0.0014 (6) | −0.0062 (6) | −0.0005 (6) |
C5 | 0.0266 (8) | 0.0150 (6) | 0.0189 (7) | −0.0011 (6) | −0.0054 (6) | −0.0017 (5) |
C6 | 0.0315 (9) | 0.0265 (8) | 0.0175 (7) | −0.0003 (7) | 0.0024 (6) | −0.0017 (6) |
C7 | 0.0296 (8) | 0.0192 (7) | 0.0215 (7) | −0.0037 (6) | −0.0004 (6) | 0.0030 (6) |
C8 | 0.0231 (7) | 0.0156 (6) | 0.0176 (7) | 0.0018 (5) | −0.0059 (5) | 0.0004 (5) |
C9 | 0.0324 (9) | 0.0199 (8) | 0.0326 (9) | 0.0098 (7) | −0.0105 (7) | −0.0055 (7) |
C10 | 0.0213 (7) | 0.0190 (7) | 0.0209 (7) | −0.0008 (6) | −0.0055 (6) | 0.0002 (6) |
C11 | 0.0293 (9) | 0.0247 (8) | 0.0300 (9) | −0.0003 (7) | −0.0139 (7) | 0.0005 (7) |
C12 | 0.0229 (8) | 0.0342 (10) | 0.0321 (9) | −0.0046 (7) | 0.0008 (7) | 0.0042 (8) |
C13 | 0.0251 (8) | 0.0279 (8) | 0.0195 (7) | −0.0065 (7) | −0.0064 (6) | 0.0014 (6) |
C14 | 0.0336 (10) | 0.0541 (13) | 0.0203 (8) | −0.0105 (9) | −0.0038 (7) | −0.0083 (9) |
C15 | 0.0169 (7) | 0.0223 (7) | 0.0211 (7) | −0.0007 (6) | 0.0007 (5) | 0.0052 (6) |
C16 | 0.0252 (8) | 0.0194 (7) | 0.0320 (9) | 0.0048 (6) | −0.0024 (7) | 0.0057 (7) |
C17 | 0.0179 (7) | 0.0167 (7) | 0.0183 (7) | −0.0016 (5) | −0.0019 (5) | −0.0026 (5) |
C18 | 0.0170 (6) | 0.0142 (6) | 0.0204 (7) | 0.0002 (5) | −0.0014 (5) | −0.0006 (5) |
C19 | 0.0176 (6) | 0.0140 (6) | 0.0178 (7) | −0.0001 (5) | −0.0007 (5) | −0.0008 (5) |
C20 | 0.0259 (8) | 0.0141 (6) | 0.0199 (7) | −0.0004 (6) | −0.0041 (6) | −0.0038 (6) |
C21 | 0.0263 (8) | 0.0173 (6) | 0.0178 (7) | −0.0035 (6) | −0.0056 (6) | 0.0000 (5) |
C22 | 0.0215 (7) | 0.0291 (8) | 0.0273 (8) | −0.0067 (6) | −0.0028 (6) | 0.0080 (7) |
C23 | 0.0196 (7) | 0.0331 (9) | 0.0213 (7) | 0.0020 (6) | 0.0007 (6) | 0.0013 (7) |
C24 | 0.0187 (7) | 0.0186 (7) | 0.0178 (7) | 0.0022 (5) | −0.0046 (5) | −0.0004 (5) |
C25 | 0.0315 (9) | 0.0176 (7) | 0.0331 (9) | 0.0069 (7) | −0.0098 (7) | −0.0020 (7) |
C26 | 0.0231 (7) | 0.0177 (6) | 0.0162 (6) | −0.0010 (6) | −0.0020 (5) | 0.0018 (5) |
C27 | 0.0362 (9) | 0.0281 (8) | 0.0214 (8) | 0.0001 (7) | −0.0101 (7) | 0.0040 (7) |
C28 | 0.0340 (9) | 0.0250 (8) | 0.0255 (8) | −0.0005 (7) | 0.0084 (7) | 0.0028 (7) |
C29 | 0.0191 (7) | 0.0180 (7) | 0.0209 (7) | 0.0003 (5) | −0.0027 (5) | −0.0027 (6) |
C30 | 0.0272 (9) | 0.0578 (14) | 0.0195 (8) | −0.0084 (9) | −0.0044 (7) | −0.0071 (8) |
C31 | 0.0157 (6) | 0.0164 (6) | 0.0207 (7) | −0.0009 (5) | 0.0000 (5) | 0.0015 (6) |
C32 | 0.0230 (8) | 0.0164 (7) | 0.0347 (9) | 0.0044 (6) | −0.0014 (6) | 0.0033 (6) |
O1—C13 | 1.316 (2) | C3—C4 | 1.498 (2) |
O1—C14 | 1.448 (2) | C4—C5 | 1.533 (2) |
O2—C13 | 1.191 (3) | C5—C10 | 1.547 (2) |
O3—C15 | 1.339 (2) | C5—C6 | 1.552 (2) |
O3—C16 | 1.445 (2) | C6—C7 | 1.551 (3) |
O4—C15 | 1.209 (2) | C7—C8 | 1.545 (2) |
O5—C29 | 1.323 (2) | C8—C9 | 1.514 (2) |
O5—C30 | 1.449 (2) | C8—C10 | 1.553 (2) |
O6—C29 | 1.205 (2) | C10—C12 | 1.529 (3) |
O7—C31 | 1.346 (2) | C10—C11 | 1.544 (2) |
O7—C32 | 1.446 (2) | C17—C18 | 1.411 (2) |
O8—C31 | 1.209 (2) | C17—C29 | 1.495 (2) |
N1—C3 | 1.349 (2) | C18—C19 | 1.396 (2) |
N1—N2 | 1.3631 (19) | C18—C31 | 1.462 (2) |
N1—C8 | 1.487 (2) | C19—C20 | 1.493 (2) |
N2—C1 | 1.330 (2) | C20—C21 | 1.532 (2) |
N3—C19 | 1.347 (2) | C21—C26 | 1.551 (2) |
N3—N4 | 1.3660 (18) | C21—C22 | 1.551 (3) |
N3—C24 | 1.495 (2) | C22—C23 | 1.548 (3) |
N4—C17 | 1.327 (2) | C23—C24 | 1.538 (2) |
C1—C2 | 1.414 (2) | C24—C25 | 1.519 (2) |
C1—C13 | 1.493 (2) | C24—C26 | 1.555 (2) |
C2—C3 | 1.394 (2) | C26—C28 | 1.528 (2) |
C2—C15 | 1.460 (2) | C26—C27 | 1.538 (2) |
C13—O1—C14 | 115.80 (15) | O2—C13—O1 | 124.67 (18) |
C15—O3—C16 | 115.30 (14) | O2—C13—C1 | 123.38 (18) |
C29—O5—C30 | 114.94 (14) | O1—C13—C1 | 111.95 (15) |
C31—O7—C32 | 115.56 (14) | O4—C15—O3 | 124.26 (16) |
C3—N1—N2 | 113.11 (13) | O4—C15—C2 | 123.59 (17) |
C3—N1—C8 | 124.69 (13) | O3—C15—C2 | 112.14 (14) |
N2—N1—C8 | 120.98 (13) | N4—C17—C18 | 112.24 (14) |
C1—N2—N1 | 104.11 (13) | N4—C17—C29 | 119.84 (15) |
C19—N3—N4 | 113.11 (13) | C18—C17—C29 | 127.86 (15) |
C19—N3—C24 | 125.59 (13) | C19—C18—C17 | 104.36 (14) |
N4—N3—C24 | 121.03 (13) | C19—C18—C31 | 130.14 (14) |
C17—N4—N3 | 104.07 (13) | C17—C18—C31 | 125.49 (14) |
N2—C1—C2 | 112.12 (14) | N3—C19—C18 | 106.22 (13) |
N2—C1—C13 | 119.35 (16) | N3—C19—C20 | 120.27 (14) |
C2—C1—C13 | 128.44 (16) | C18—C19—C20 | 133.49 (14) |
C3—C2—C1 | 104.33 (14) | C19—C20—C21 | 110.02 (13) |
C3—C2—C15 | 130.16 (16) | C20—C21—C26 | 111.33 (13) |
C1—C2—C15 | 125.48 (15) | C20—C21—C22 | 110.44 (13) |
N1—C3—C2 | 106.30 (14) | C26—C21—C22 | 103.35 (13) |
N1—C3—C4 | 120.39 (14) | C23—C22—C21 | 105.96 (14) |
C2—C3—C4 | 133.31 (15) | C24—C23—C22 | 104.75 (14) |
C3—C4—C5 | 109.71 (13) | N3—C24—C25 | 109.63 (14) |
C4—C5—C10 | 110.90 (13) | N3—C24—C23 | 106.91 (13) |
C4—C5—C6 | 110.74 (14) | C25—C24—C23 | 114.89 (15) |
C10—C5—C6 | 103.41 (13) | N3—C24—C26 | 105.65 (12) |
C7—C6—C5 | 106.01 (13) | C25—C24—C26 | 116.22 (14) |
C8—C7—C6 | 104.53 (13) | C23—C24—C26 | 102.73 (13) |
N1—C8—C9 | 109.42 (14) | C28—C26—C27 | 107.99 (14) |
N1—C8—C7 | 105.62 (13) | C28—C26—C21 | 115.23 (14) |
C9—C8—C7 | 114.36 (15) | C27—C26—C21 | 109.16 (14) |
N1—C8—C10 | 106.54 (12) | C28—C26—C24 | 113.68 (14) |
C9—C8—C10 | 116.79 (14) | C27—C26—C24 | 111.06 (14) |
C7—C8—C10 | 103.26 (13) | C21—C26—C24 | 99.53 (12) |
C12—C10—C11 | 108.34 (15) | O6—C29—O5 | 124.70 (16) |
C12—C10—C5 | 114.65 (14) | O6—C29—C17 | 123.58 (16) |
C11—C10—C5 | 109.68 (14) | O5—C29—C17 | 111.70 (14) |
C12—C10—C8 | 114.01 (14) | O8—C31—O7 | 123.98 (15) |
C11—C10—C8 | 110.27 (13) | O8—C31—C18 | 124.05 (16) |
C5—C10—C8 | 99.65 (13) | O7—C31—C18 | 111.97 (13) |
C3—N1—N2—C1 | 1.85 (18) | C3—C2—C15—O3 | −6.0 (2) |
C8—N1—N2—C1 | 169.80 (14) | C1—C2—C15—O3 | 171.40 (15) |
C19—N3—N4—C17 | 0.34 (18) | N3—N4—C17—C18 | −0.09 (18) |
C24—N3—N4—C17 | 174.59 (14) | N3—N4—C17—C29 | 177.19 (13) |
N1—N2—C1—C2 | −0.93 (18) | N4—C17—C18—C19 | −0.17 (19) |
N1—N2—C1—C13 | −177.68 (14) | C29—C17—C18—C19 | −177.18 (15) |
N2—C1—C2—C3 | −0.23 (19) | N4—C17—C18—C31 | −179.03 (15) |
C13—C1—C2—C3 | 176.16 (16) | C29—C17—C18—C31 | 4.0 (3) |
N2—C1—C2—C15 | −178.21 (15) | N4—N3—C19—C18 | −0.45 (18) |
C13—C1—C2—C15 | −1.8 (3) | C24—N3—C19—C18 | −174.39 (14) |
N2—N1—C3—C2 | −2.03 (18) | N4—N3—C19—C20 | −179.10 (14) |
C8—N1—C3—C2 | −169.45 (15) | C24—N3—C19—C20 | 7.0 (2) |
N2—N1—C3—C4 | 178.32 (14) | C17—C18—C19—N3 | 0.36 (17) |
C8—N1—C3—C4 | 10.9 (2) | C31—C18—C19—N3 | 179.14 (16) |
C1—C2—C3—N1 | 1.31 (17) | C17—C18—C19—C20 | 178.75 (17) |
C15—C2—C3—N1 | 179.16 (16) | C31—C18—C19—C20 | −2.5 (3) |
C1—C2—C3—C4 | −179.11 (17) | N3—C19—C20—C21 | −10.7 (2) |
C15—C2—C3—C4 | −1.3 (3) | C18—C19—C20—C21 | 171.11 (17) |
N1—C3—C4—C5 | −14.9 (2) | C19—C20—C21—C26 | 46.86 (18) |
C2—C3—C4—C5 | 165.61 (17) | C19—C20—C21—C22 | −67.36 (17) |
C3—C4—C5—C10 | 49.11 (18) | C20—C21—C22—C23 | 95.31 (16) |
C3—C4—C5—C6 | −65.10 (17) | C26—C21—C22—C23 | −23.86 (16) |
C4—C5—C6—C7 | 93.59 (16) | C21—C22—C23—C24 | −5.88 (17) |
C10—C5—C6—C7 | −25.25 (17) | C19—N3—C24—C25 | −162.36 (16) |
C5—C6—C7—C8 | −3.91 (17) | N4—N3—C24—C25 | 24.1 (2) |
C3—N1—C8—C9 | −164.98 (16) | C19—N3—C24—C23 | 72.52 (19) |
N2—N1—C8—C9 | 28.5 (2) | N4—N3—C24—C23 | −100.98 (17) |
C3—N1—C8—C7 | 71.48 (19) | C19—N3—C24—C26 | −36.4 (2) |
N2—N1—C8—C7 | −95.01 (17) | N4—N3—C24—C26 | 150.10 (14) |
C3—N1—C8—C10 | −37.9 (2) | C22—C23—C24—N3 | −77.59 (15) |
N2—N1—C8—C10 | 155.63 (14) | C22—C23—C24—C25 | 160.54 (14) |
C6—C7—C8—N1 | −80.12 (15) | C22—C23—C24—C26 | 33.37 (16) |
C6—C7—C8—C9 | 159.52 (15) | C20—C21—C26—C28 | 47.05 (18) |
C6—C7—C8—C10 | 31.57 (16) | C22—C21—C26—C28 | 165.61 (14) |
C4—C5—C10—C12 | 47.38 (19) | C20—C21—C26—C27 | 168.73 (14) |
C6—C5—C10—C12 | 166.11 (14) | C22—C21—C26—C27 | −72.71 (16) |
C4—C5—C10—C11 | 169.50 (14) | C20—C21—C26—C24 | −74.91 (15) |
C6—C5—C10—C11 | −71.77 (16) | C22—C21—C26—C24 | 43.65 (14) |
C4—C5—C10—C8 | −74.78 (15) | N3—C24—C26—C28 | −58.82 (17) |
C6—C5—C10—C8 | 43.95 (15) | C25—C24—C26—C28 | 62.98 (19) |
N1—C8—C10—C12 | −58.39 (18) | C23—C24—C26—C28 | −170.71 (14) |
C9—C8—C10—C12 | 64.2 (2) | N3—C24—C26—C27 | 179.16 (14) |
C7—C8—C10—C12 | −169.41 (14) | C25—C24—C26—C27 | −59.04 (19) |
N1—C8—C10—C11 | 179.48 (14) | C23—C24—C26—C27 | 67.27 (16) |
C9—C8—C10—C11 | −57.9 (2) | N3—C24—C26—C21 | 64.24 (14) |
C7—C8—C10—C11 | 68.47 (17) | C25—C24—C26—C21 | −173.96 (15) |
N1—C8—C10—C5 | 64.22 (15) | C23—C24—C26—C21 | −47.65 (15) |
C9—C8—C10—C5 | −173.21 (15) | C30—O5—C29—O6 | −5.6 (3) |
C7—C8—C10—C5 | −46.80 (15) | C30—O5—C29—C17 | 175.59 (17) |
C14—O1—C13—O2 | 1.4 (4) | N4—C17—C29—O6 | −79.6 (2) |
C14—O1—C13—C1 | −178.29 (17) | C18—C17—C29—O6 | 97.2 (2) |
N2—C1—C13—O2 | 80.4 (3) | N4—C17—C29—O5 | 99.19 (19) |
C2—C1—C13—O2 | −95.8 (3) | C18—C17—C29—O5 | −84.0 (2) |
N2—C1—C13—O1 | −100.0 (2) | C32—O7—C31—O8 | −0.2 (2) |
C2—C1—C13—O1 | 83.9 (2) | C32—O7—C31—C18 | −179.96 (14) |
C16—O3—C15—O4 | 1.2 (2) | C19—C18—C31—O8 | −171.45 (17) |
C16—O3—C15—C2 | −178.05 (14) | C17—C18—C31—O8 | 7.1 (3) |
C3—C2—C15—O4 | 174.75 (17) | C19—C18—C31—O7 | 8.4 (2) |
C1—C2—C15—O4 | −7.8 (3) | C17—C18—C31—O7 | −173.09 (15) |
D—H···A | D—H | H···A | D···A | D—H···A |
C16—H16B···O8 | 0.98 | 2.42 | 3.349 (2) | 157 |
C22—H22B···O4i | 0.99 | 2.57 | 3.516 (2) | 160 |
C25—H25A···O2ii | 0.98 | 2.55 | 3.519 (3) | 170 |
C32—H32A···O4 | 0.98 | 2.45 | 3.395 (2) | 163 |
C16—H16C···Cg2iii | 0.98 | 2.64 | 3.529 (3) | 151 |
C32—H32C···Cg1i | 0.98 | 2.70 | 3.617 (3) | 155 |
Symmetry codes: (i) x−1, y, z; (ii) −x, y+1/2, −z; (iii) x+1, y, z. |
Experimental details
Crystal data | |
Chemical formula | C16H22N2O4 |
Mr | 306.36 |
Crystal system, space group | Monoclinic, P21 |
Temperature (K) | 143 |
a, b, c (Å) | 7.3772 (14), 20.063 (3), 10.4576 (12) |
β (°) | 90.513 (12) |
V (Å3) | 1547.7 (4) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 0.10 |
Crystal size (mm) | 0.70 × 0.40 × 0.36 |
Data collection | |
Diffractometer | SIEMENS SMART diffractometer |
Absorption correction | Numerical six indexed faces (SHELXTL; Sheldrick, 1996) |
Tmin, Tmax | 0.943, 0.969 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 30858, 4858, 4589 |
Rint | 0.029 |
(sin θ/λ)max (Å−1) | 0.725 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.036, 0.096, 1.08 |
No. of reflections | 4858 |
No. of parameters | 407 |
No. of restraints | 1 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.44, −0.30 |
Computer programs: SMART (Siemens, 1995), SMART, SAINT (Siemens, 1995), SHELXS97 (Sheldrick, 1997), XP in SHELXTL (Sheldrick, 1996), CIF in SHELXL97 (Sheldrick, 1997).
D—H···A | D—H | H···A | D···A | D—H···A |
C16—H16B···O8 | 0.98 | 2.42 | 3.349 (2) | 157 |
C22—H22B···O4i | 0.99 | 2.57 | 3.516 (2) | 160 |
C25—H25A···O2ii | 0.98 | 2.55 | 3.519 (3) | 170 |
C32—H32A···O4 | 0.98 | 2.45 | 3.395 (2) | 163 |
C16—H16C···Cg2iii | 0.98 | 2.64 | 3.529 (3) | 151 |
C32—H32C···Cg1i | 0.98 | 2.70 | 3.617 (3) | 155 |
Symmetry codes: (i) x−1, y, z; (ii) −x, y+1/2, −z; (iii) x+1, y, z. |
The structure of the title compound, (I), contains two crystallographically independent molecules (Fig. 1). Equivalent bond distances and angles between the two molecules agree within experimental uncertainty, except for the C13—O2 bond length of 1.191 (3) Å which appears slightly too short due to the large thermal motion of atom O2. The conformation angles within the bicylooctane groups of both molecules are rather similar: torsion angles about related bonds agree within 3°. The torsion angles about related bonds in the pyrazoledicarboxylate groups of the two molecules, however, have opposite signs. The pyrazole groups are planar. π bonding in the pyrazole rings is considerably delocalized. The carboxylate groups attached to C2 and C18 are almost coplanar with the pyrazole planes. The carboxylate groups attached to C1 and C17 are almost perpendicular to the pyrazole planes. Consequently the C2—C15 and C18—C31 bonds are about 0.03 Å shorter than the corresponding C1—C13 and C17—C29 bonds due to resonance. \sch
The molecules show no short intramolecular contacts. The crystal packing shows four intermolecular C—H···O interactions with H···O distances between 2.42 and 2.57 Å and C—H—O angles between 157 and 170° (Table 1). There also are two intermolecular C—H···π interactions between methyl groups and the π - system of the pyrazole groups with H···Cg distances of 2.64 and 2.70 Å and C—H···Cg angles of 151 and 155° (Cg1 represents the midpoint of the pyrazole ring of molecule 1 and Cg2 the midpoint of the pyrazole ring of molecule 2). A close inspection of the crystal structure shows a pseudo-centrosymmetric packing of the molecules. The achiral parts of the two molecules are symmetrically arranged about a pseudo-inversion center at 0.5 0.5 0.25. 14 atom pairs among those groups satisfy the center of symmetry within a tolerance of 0.17 Å. The two shortest intermolecular C—H···O contacts connect the molecules of this pseudo- centrosymmetric dimer (Fig. 1, Fig. 2). The H···O distances of about 2.45 Å are short for C—H···O interactions involving methyl groups (Desiraju & Steiner, 1999). The chiral parts of the molecules result in deviations from a centrosymmetric structure. The structure has a pseudo-P21/c packing. The average intensity of the h 0 l reflections with l odd is only about 25% of the average intensity of general reflections. Approximate P21/c symmetry in space group P21 with Z = 4 was also observed by one of us in the crystal structure of a 23 atom containing molecule with two chiral C atoms (Volk et al., 1998, CSD-refcode: JOGYAF). The achiral atoms of the two independent molecules in that structure are very closely related by a pseudo-inversion center. 19 non-H atoms have centrosymmetric counterparts within a tolerance of 0.23 Å. In order to get an idea of the number of crystal structures of chiral compounds which crystallize in P21 with two independent molecules related by a pseudo- inversion center, a search for such structures was performed in the spring 2000 release of the Cambridge Structural Database (Allen & Kennard, 1993). The search was limited to a subset containing the first 34378 entries in the data base (i.e. the refcodes starting with the characters A, B and C). The number of crystal structures with space group P21 and Z = 4 in this subset with coordinates reported is 318. A l l 318 structures were searched for pseudo-inversion centers using the ADDSYM option in program PLATON (Spek, 1998). For a number of structures pseudo-inversion centers were detected at 0.25 y 0, 0 y 0.25 or 0.25 y 0.25. Thus these structures approximately have P21/a, P21/c or P21/n symmetry. In a final test, the coordinates of the independent molecules were directly compared. A total of 31 chiral structures were found with pseudo-P21/c (or the equivalent pseudo-P21/a and pseudo-P21/n) symmetry. The refcodes are: ADRBFT10, AIPTHL10, APFMHA, ATRVND10, BABJIX, BADMUO, BAGMEB10, BAGMOL10, BAPZUN, BECSOR10, BIWFIW, BOJWAY, BOSWEL, BOXCPT10, BOXYOC, BPICAM, BRUDAG, BUYGUX, CAKHAX, CAMMEI, CAMPHX10, CELNAI, CITSUT10, CMETPT10, COBDAY, COGBIJ, COHRUM, COKWOO, COKWUU, CONHUI and CUCCIM. Some of these structures were reported as pseudo-centrosymmetric in the original publications (Goodwin et al., 1984; Kurihara et al., 1983; 1984, Ohashi et al., 1982; Perales et al., 1984; Trowitzsch et al., 1981; Uchida et al., 1984; Ziolo et al., 1982). Thus about 10% of the crystal structures reported in the literature with space group P21 and Z = 4 are chiral compounds with a pseudo-P21/c packing. This number probably is a low estimate of the real number of pseudo-symmetric structures as ADDSYM with default parameters only selects structures with at least 80% of the atoms fulfilling the (pseudo)-symmetry criterium within a tolerance of 0.45 Å. Larger misfit tolerances result in additional hits. Space group P21/c is not allowed for chiral compounds. The present investigation shows, however, that in some cases an approximate P21/c type packing is preferred for chiral compounds.