
Supporting information
![]() | Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270101003870/gd1142sup1.cif |
![]() | Structure factor file (CIF format) https://doi.org/10.1107/S0108270101003870/gd1142IVasup2.hkl |
CCDC reference: 166987
As noted above, the diastereomers (IVa) and (IVb) were synthesized by a three-step reaction (Scheme). In the first step, to bromomethylbenzophenone, (I), prepared freshly from 2-methylbenzophenone (1.96 g, 0.01 mol) and N-bromosuccinimide (1.76 g, 0.01 mol), was added phthalimide (1.5 g, 0.01 mol), potassium carbonate (1.1.g, 8 mmol) and N,N-dimethylformamide (25 ml). The mixture was stirred overnight, diluted with water, extracted with diethyl ether (3 × 20 ml) and dried (magnesium sulfate). The solvent was evaporated under reduced pressure and the solid recrystallized from ethanol to give 2-(N-phthalimido-methyl)benzophenone, (II) (77% yield, m.p. 388 K). In the second step, to a mixture of (II) (0.5 g, 15 mmol) in dry methanol (20 ml) at 273–283 K was added sodium borohydride (0.69 g, 30 mmol) by portions. The mixture was stirred for 2 h and monitored by thin layer chromatography (dichloromethane/acetone 5:1). After 2 h, the starting material disappeared and the excess of sodium borohydride was decomposed by addition of cold water (10 ml) and 10% hydrochloric acid to neutral pH. The precipitate was separated by filtration, washed with water, dried, concentrated under reduced pressure and recrystallized from ethanol to afford a 5:1 ratio of diastereomers of (III) (79% yield). Finally, compound (IV) was prepared when the diols (III) (0.5 g, 1.5 mmol) were stirred in dry dichloromethane (20 ml) with a catalytic amount of p-toluene-sulfonic acid for 30 min at room temperature. The solution was washed with saturated sodium hydrogen carbonate and then with water, then dried and concentrated under reduced pressure. Separation by flash chromatography, followed by recrystallization from ethanol, gave the corresponding 5:1 ratio of the oxazepines (IVa) and (IVb) [70% yield; (IVa) m.p. 496 K, (IVb) m.p. 482 K]. The isomers were initially characterized by IR, 1H and 13C NMR spectral analyses.
Although most of the H atoms were seen in a difference Fourier map, all were treated as riding atoms, with C—H 0.93 Å (aromatic) or 0.97 Å, and with Uiso set to 1.2 (1.5 for the methyl-H atoms) times Ueq of the parent atom.
Data collection: P21 software (Syntex, 1973); cell refinement: P21 software; data reduction: XP21 (Pavelčík, 1987); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEPII (Johnson, 1976); software used to prepare material for publication: SHELXL97.
![]() | Fig. 1. The molecular structure of (IVa), showing the atom-labelling scheme. Displacement ellipsoids are shown at the 30% probability level and H atoms are drawn as small circles of arbitrary radii. |
C22H17NO2 | Z = 2 |
Mr = 327.37 | F(000) = 344 |
Triclinic, P1 | Dx = 1.361 Mg m−3 Dm = 1.36 (1) Mg m−3 Dm measured by flotation in bromoform/c-hexane |
a = 7.153 (3) Å | Mo Kα radiation, λ = 0.71073 Å |
b = 8.961 (4) Å | Cell parameters from 15 reflections |
c = 13.156 (7) Å | θ = 10–26° |
α = 92.69 (5)° | µ = 0.09 mm−1 |
β = 106.83 (5)° | T = 293 K |
γ = 96.79 (4)° | Prism, colourless |
V = 798.6 (6) Å3 | 0.50 × 0.35 × 0.30 mm |
Syntex P21 diffractometer | Rint = 0.000 |
Radiation source: fine-focus sealed tube | θmax = 26.6°, θmin = 1.6° |
Graphite monochromator | h = 0→8 |
θ/2θ scans | k = −11→11 |
3271 measured reflections | l = −15→15 |
3271 independent reflections | 2 standard reflections every 98 reflections |
2513 reflections with I > 2σ(I) | intensity decay: 2% |
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)] = 0.047 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.133 | H-atom parameters constrained |
S = 1.10 | w = 1/[σ2(Fo2) + (0.0478P)2 + 0.3839P] where P = (Fo2 + 2Fc2)/3 |
3271 reflections | (Δ/σ)max = 0.001 |
226 parameters | Δρmax = 0.17 e Å−3 |
0 restraints | Δρmin = −0.23 e Å−3 |
C22H17NO2 | γ = 96.79 (4)° |
Mr = 327.37 | V = 798.6 (6) Å3 |
Triclinic, P1 | Z = 2 |
a = 7.153 (3) Å | Mo Kα radiation |
b = 8.961 (4) Å | µ = 0.09 mm−1 |
c = 13.156 (7) Å | T = 293 K |
α = 92.69 (5)° | 0.50 × 0.35 × 0.30 mm |
β = 106.83 (5)° |
Syntex P21 diffractometer | Rint = 0.000 |
3271 measured reflections | 2 standard reflections every 98 reflections |
3271 independent reflections | intensity decay: 2% |
2513 reflections with I > 2σ(I) |
R[F2 > 2σ(F2)] = 0.047 | 0 restraints |
wR(F2) = 0.133 | H-atom parameters constrained |
S = 1.10 | Δρmax = 0.17 e Å−3 |
3271 reflections | Δρmin = −0.23 e Å−3 |
226 parameters |
x | y | z | Uiso*/Ueq | ||
N1 | 0.0848 (2) | 0.54542 (18) | 0.19931 (13) | 0.0415 (4) | |
C2 | −0.1132 (3) | 0.5412 (2) | 0.16670 (16) | 0.0422 (4) | |
O2 | −0.2302 (2) | 0.46772 (17) | 0.20239 (13) | 0.0561 (4) | |
C3 | −0.1563 (3) | 0.6398 (2) | 0.07878 (15) | 0.0409 (4) | |
C4 | −0.3325 (3) | 0.6773 (3) | 0.01932 (18) | 0.0516 (5) | |
H4 | −0.4500 | 0.6400 | 0.0319 | 0.062* | |
C5 | −0.3307 (4) | 0.7718 (3) | −0.0595 (2) | 0.0618 (6) | |
H5 | −0.4488 | 0.7983 | −0.1016 | 0.074* | |
C6 | −0.1573 (4) | 0.8276 (3) | −0.07698 (18) | 0.0627 (7) | |
H6 | −0.1595 | 0.8923 | −0.1304 | 0.075* | |
C7 | 0.0210 (3) | 0.7899 (3) | −0.01693 (16) | 0.0532 (6) | |
H7 | 0.1386 | 0.8279 | −0.0291 | 0.064* | |
C8 | 0.0184 (3) | 0.6948 (2) | 0.06115 (15) | 0.0408 (4) | |
C9 | 0.1851 (3) | 0.6373 (2) | 0.13913 (15) | 0.0404 (4) | |
H9 | 0.2529 | 0.5754 | 0.1018 | 0.049* | |
O10 | 0.31652 (17) | 0.75939 (14) | 0.19990 (10) | 0.0377 (3) | |
C11 | 0.4839 (3) | 0.7170 (2) | 0.27827 (14) | 0.0356 (4) | |
H11 | 0.5116 | 0.6203 | 0.2522 | 0.043* | |
C12 | 0.4331 (3) | 0.6954 (2) | 0.38107 (15) | 0.0362 (4) | |
C13 | 0.5160 (3) | 0.7937 (2) | 0.47093 (15) | 0.0417 (4) | |
H13 | 0.6087 | 0.8751 | 0.4697 | 0.050* | |
C14 | 0.4636 (3) | 0.7732 (3) | 0.56251 (17) | 0.0506 (5) | |
H14 | 0.5198 | 0.8411 | 0.6223 | 0.061* | |
C15 | 0.3293 (3) | 0.6534 (3) | 0.56582 (18) | 0.0556 (6) | |
H15 | 0.2951 | 0.6386 | 0.6280 | 0.067* | |
C16 | 0.2453 (3) | 0.5553 (3) | 0.47701 (18) | 0.0497 (5) | |
H16 | 0.1537 | 0.4738 | 0.4795 | 0.060* | |
C17 | 0.2933 (3) | 0.5745 (2) | 0.38409 (16) | 0.0393 (4) | |
C18 | 0.1915 (3) | 0.4686 (2) | 0.28720 (17) | 0.0476 (5) | |
H18A | 0.2887 | 0.4182 | 0.2659 | 0.057* | |
H18B | 0.1005 | 0.3922 | 0.3046 | 0.057* | |
C19 | 0.6588 (3) | 0.8329 (2) | 0.28892 (14) | 0.0353 (4) | |
C20 | 0.6422 (3) | 0.9667 (2) | 0.24348 (17) | 0.0454 (5) | |
H20 | 0.5192 | 0.9868 | 0.2030 | 0.055* | |
C21 | 0.8057 (3) | 1.0716 (3) | 0.25713 (19) | 0.0556 (6) | |
H21 | 0.7927 | 1.1627 | 0.2264 | 0.067* | |
C22 | 0.9873 (3) | 1.0429 (3) | 0.3155 (2) | 0.0560 (6) | |
H22 | 1.0976 | 1.1144 | 0.3249 | 0.067* | |
C23 | 1.0067 (3) | 0.9091 (3) | 0.36012 (19) | 0.0541 (6) | |
H23 | 1.1302 | 0.8888 | 0.3997 | 0.065* | |
C24 | 0.8437 (3) | 0.8047 (2) | 0.34633 (18) | 0.0475 (5) | |
H24 | 0.8577 | 0.7132 | 0.3762 | 0.057* |
U11 | U22 | U33 | U12 | U13 | U23 | |
N1 | 0.0335 (8) | 0.0388 (9) | 0.0466 (9) | −0.0014 (7) | 0.0052 (7) | 0.0075 (7) |
C2 | 0.0421 (11) | 0.0352 (10) | 0.0455 (11) | 0.0014 (8) | 0.0091 (9) | 0.0002 (8) |
O2 | 0.0456 (8) | 0.0530 (9) | 0.0684 (10) | −0.0045 (7) | 0.0177 (7) | 0.0174 (8) |
C3 | 0.0395 (10) | 0.0377 (10) | 0.0402 (10) | −0.0003 (8) | 0.0064 (8) | −0.0007 (8) |
C4 | 0.0394 (11) | 0.0513 (12) | 0.0584 (13) | 0.0039 (9) | 0.0063 (10) | 0.0063 (10) |
C5 | 0.0527 (14) | 0.0617 (15) | 0.0599 (14) | 0.0097 (11) | −0.0028 (11) | 0.0147 (12) |
C6 | 0.0687 (16) | 0.0651 (15) | 0.0451 (12) | 0.0012 (12) | 0.0035 (11) | 0.0177 (11) |
C7 | 0.0522 (13) | 0.0618 (14) | 0.0401 (11) | −0.0060 (10) | 0.0103 (10) | 0.0064 (10) |
C8 | 0.0403 (10) | 0.0424 (10) | 0.0347 (10) | −0.0013 (8) | 0.0068 (8) | −0.0014 (8) |
C9 | 0.0354 (10) | 0.0430 (11) | 0.0400 (10) | −0.0008 (8) | 0.0095 (8) | 0.0003 (8) |
O10 | 0.0301 (6) | 0.0384 (7) | 0.0395 (7) | −0.0003 (5) | 0.0042 (5) | 0.0050 (5) |
C11 | 0.0318 (9) | 0.0343 (9) | 0.0395 (10) | 0.0057 (7) | 0.0079 (7) | 0.0050 (8) |
C12 | 0.0292 (9) | 0.0367 (9) | 0.0433 (10) | 0.0095 (7) | 0.0086 (8) | 0.0108 (8) |
C13 | 0.0375 (10) | 0.0435 (11) | 0.0432 (11) | 0.0091 (8) | 0.0088 (8) | 0.0063 (8) |
C14 | 0.0475 (12) | 0.0631 (14) | 0.0410 (11) | 0.0158 (10) | 0.0092 (9) | 0.0056 (10) |
C15 | 0.0521 (13) | 0.0748 (16) | 0.0474 (12) | 0.0188 (12) | 0.0198 (10) | 0.0225 (12) |
C16 | 0.0386 (11) | 0.0555 (13) | 0.0583 (13) | 0.0097 (9) | 0.0148 (10) | 0.0271 (11) |
C17 | 0.0315 (9) | 0.0382 (10) | 0.0478 (11) | 0.0088 (8) | 0.0077 (8) | 0.0150 (8) |
C18 | 0.0438 (11) | 0.0354 (10) | 0.0581 (13) | 0.0023 (8) | 0.0064 (9) | 0.0135 (9) |
C19 | 0.0319 (9) | 0.0373 (10) | 0.0374 (9) | 0.0042 (7) | 0.0115 (7) | 0.0036 (7) |
C20 | 0.0355 (10) | 0.0451 (11) | 0.0524 (12) | 0.0044 (8) | 0.0068 (9) | 0.0134 (9) |
C21 | 0.0473 (12) | 0.0486 (12) | 0.0672 (15) | −0.0020 (10) | 0.0125 (11) | 0.0193 (11) |
C22 | 0.0380 (11) | 0.0558 (14) | 0.0708 (15) | −0.0068 (10) | 0.0151 (10) | 0.0111 (11) |
C23 | 0.0275 (10) | 0.0592 (14) | 0.0711 (15) | 0.0042 (9) | 0.0074 (10) | 0.0100 (11) |
C24 | 0.0384 (10) | 0.0435 (11) | 0.0590 (13) | 0.0093 (9) | 0.0091 (9) | 0.0128 (10) |
N1—C2 | 1.350 (3) | C12—C17 | 1.395 (3) |
N1—C9 | 1.439 (3) | C13—C14 | 1.376 (3) |
N1—C18 | 1.443 (3) | C13—H13 | 0.9300 |
C2—O2 | 1.217 (2) | C14—C15 | 1.364 (3) |
C2—C3 | 1.473 (3) | C14—H14 | 0.9300 |
C3—C4 | 1.366 (3) | C15—C16 | 1.368 (3) |
C3—C8 | 1.376 (3) | C15—H15 | 0.9300 |
C4—C5 | 1.372 (3) | C16—C17 | 1.375 (3) |
C4—H4 | 0.9300 | C16—H16 | 0.9300 |
C5—C6 | 1.367 (4) | C17—C18 | 1.497 (3) |
C5—H5 | 0.9300 | C18—H18A | 0.9700 |
C6—C7 | 1.382 (3) | C18—H18B | 0.9700 |
C6—H6 | 0.9300 | C19—C20 | 1.367 (3) |
C7—C8 | 1.368 (3) | C19—C24 | 1.379 (3) |
C7—H7 | 0.9300 | C20—C21 | 1.374 (3) |
C8—C9 | 1.492 (3) | C20—H20 | 0.9300 |
C9—O10 | 1.399 (2) | C21—C22 | 1.365 (3) |
C9—H9 | 0.9800 | C21—H21 | 0.9300 |
O10—C11 | 1.439 (2) | C22—C23 | 1.363 (3) |
C11—C19 | 1.497 (3) | C22—H22 | 0.9300 |
C11—C12 | 1.514 (3) | C23—C24 | 1.368 (3) |
C11—H11 | 0.9800 | C23—H23 | 0.9300 |
C12—C13 | 1.378 (3) | C24—H24 | 0.9300 |
C2—N1—C9 | 113.90 (16) | C14—C13—C12 | 120.9 (2) |
C2—N1—C18 | 124.57 (17) | C14—C13—H13 | 119.5 |
C9—N1—C18 | 121.53 (16) | C12—C13—H13 | 119.5 |
O2—C2—N1 | 126.21 (19) | C15—C14—C13 | 120.2 (2) |
O2—C2—C3 | 127.74 (19) | C15—C14—H14 | 119.9 |
N1—C2—C3 | 106.04 (17) | C13—C14—H14 | 119.9 |
C4—C3—C8 | 121.6 (2) | C14—C15—C16 | 119.5 (2) |
C4—C3—C2 | 130.0 (2) | C14—C15—H15 | 120.2 |
C8—C3—C2 | 108.39 (18) | C16—C15—H15 | 120.2 |
C3—C4—C5 | 117.9 (2) | C15—C16—C17 | 121.4 (2) |
C3—C4—H4 | 121.0 | C15—C16—H16 | 119.3 |
C5—C4—H4 | 121.0 | C17—C16—H16 | 119.3 |
C6—C5—C4 | 120.8 (2) | C16—C17—C12 | 119.2 (2) |
C6—C5—H5 | 119.6 | C16—C17—C18 | 119.78 (19) |
C4—C5—H5 | 119.6 | C12—C17—C18 | 121.03 (19) |
C5—C6—C7 | 121.4 (2) | N1—C18—C17 | 112.13 (17) |
C5—C6—H6 | 119.3 | N1—C18—H18A | 109.2 |
C7—C6—H6 | 119.3 | C17—C18—H18A | 109.2 |
C8—C7—C6 | 117.6 (2) | N1—C18—H18B | 109.2 |
C8—C7—H7 | 121.2 | C17—C18—H18B | 109.2 |
C6—C7—H7 | 121.2 | H18A—C18—H18B | 107.9 |
C7—C8—C3 | 120.7 (2) | C20—C19—C24 | 118.42 (18) |
C7—C8—C9 | 129.81 (19) | C20—C19—C11 | 122.25 (17) |
C3—C8—C9 | 109.51 (17) | C24—C19—C11 | 119.33 (17) |
O10—C9—N1 | 113.94 (16) | C19—C20—C21 | 120.49 (19) |
O10—C9—C8 | 109.38 (16) | C19—C20—H20 | 119.8 |
N1—C9—C8 | 102.13 (16) | C21—C20—H20 | 119.8 |
O10—C9—H9 | 110.4 | C22—C21—C20 | 120.3 (2) |
N1—C9—H9 | 110.4 | C22—C21—H21 | 119.8 |
C8—C9—H9 | 110.4 | C20—C21—H21 | 119.8 |
C9—O10—C11 | 114.19 (14) | C23—C22—C21 | 119.9 (2) |
O10—C11—C19 | 108.61 (15) | C23—C22—H22 | 120.1 |
O10—C11—C12 | 109.22 (15) | C21—C22—H22 | 120.1 |
C19—C11—C12 | 114.30 (16) | C22—C23—C24 | 119.7 (2) |
O10—C11—H11 | 108.2 | C22—C23—H23 | 120.2 |
C19—C11—H11 | 108.2 | C24—C23—H23 | 120.2 |
C12—C11—H11 | 108.2 | C23—C24—C19 | 121.2 (2) |
C13—C12—C17 | 118.83 (19) | C23—C24—H24 | 119.4 |
C13—C12—C11 | 122.21 (17) | C19—C24—H24 | 119.4 |
C17—C12—C11 | 118.94 (18) | ||
C9—N1—C2—O2 | 177.4 (2) | O10—C11—C12—C13 | −109.94 (19) |
C18—N1—C2—O2 | −3.7 (3) | C19—C11—C12—C13 | 11.9 (2) |
C9—N1—C2—C3 | −1.4 (2) | O10—C11—C12—C17 | 68.1 (2) |
C18—N1—C2—C3 | 177.58 (18) | C19—C11—C12—C17 | −170.00 (15) |
O2—C2—C3—C4 | 2.7 (4) | C17—C12—C13—C14 | 0.4 (3) |
N1—C2—C3—C4 | −178.6 (2) | C11—C12—C13—C14 | 178.49 (17) |
O2—C2—C3—C8 | −177.0 (2) | C12—C13—C14—C15 | 0.7 (3) |
N1—C2—C3—C8 | 1.8 (2) | C13—C14—C15—C16 | −0.9 (3) |
C8—C3—C4—C5 | 0.2 (3) | C14—C15—C16—C17 | 0.0 (3) |
C2—C3—C4—C5 | −179.4 (2) | C15—C16—C17—C12 | 1.1 (3) |
C3—C4—C5—C6 | −0.7 (4) | C15—C16—C17—C18 | −177.30 (19) |
C4—C5—C6—C7 | 0.7 (4) | C13—C12—C17—C16 | −1.3 (3) |
C5—C6—C7—C8 | −0.2 (4) | C11—C12—C17—C16 | −179.40 (16) |
C6—C7—C8—C3 | −0.3 (3) | C13—C12—C17—C18 | 177.07 (17) |
C6—C7—C8—C9 | −178.6 (2) | C11—C12—C17—C18 | −1.1 (3) |
C4—C3—C8—C7 | 0.2 (3) | C2—N1—C18—C17 | −104.5 (2) |
C2—C3—C8—C7 | 179.91 (19) | C9—N1—C18—C17 | 74.4 (2) |
C4—C3—C8—C9 | 178.84 (19) | C16—C17—C18—N1 | 119.3 (2) |
C2—C3—C8—C9 | −1.5 (2) | C12—C17—C18—N1 | −59.1 (2) |
C2—N1—C9—O10 | 118.34 (18) | O10—C11—C19—C20 | 10.5 (2) |
C18—N1—C9—O10 | −60.7 (2) | C12—C11—C19—C20 | −111.8 (2) |
C2—N1—C9—C8 | 0.5 (2) | O10—C11—C19—C24 | −169.53 (17) |
C18—N1—C9—C8 | −178.49 (17) | C12—C11—C19—C24 | 68.3 (2) |
C7—C8—C9—O10 | 58.1 (3) | C24—C19—C20—C21 | −1.5 (3) |
C3—C8—C9—O10 | −120.38 (18) | C11—C19—C20—C21 | 178.5 (2) |
C7—C8—C9—N1 | 179.1 (2) | C19—C20—C21—C22 | 0.6 (4) |
C3—C8—C9—N1 | 0.7 (2) | C20—C21—C22—C23 | 0.3 (4) |
N1—C9—O10—C11 | 66.4 (2) | C21—C22—C23—C24 | −0.2 (4) |
C8—C9—O10—C11 | 179.94 (15) | C22—C23—C24—C19 | −0.7 (4) |
C9—O10—C11—C19 | 145.84 (16) | C20—C19—C24—C23 | 1.6 (3) |
C9—O10—C11—C12 | −88.91 (18) | C11—C19—C24—C23 | −178.4 (2) |
Experimental details
Crystal data | |
Chemical formula | C22H17NO2 |
Mr | 327.37 |
Crystal system, space group | Triclinic, P1 |
Temperature (K) | 293 |
a, b, c (Å) | 7.153 (3), 8.961 (4), 13.156 (7) |
α, β, γ (°) | 92.69 (5), 106.83 (5), 96.79 (4) |
V (Å3) | 798.6 (6) |
Z | 2 |
Radiation type | Mo Kα |
µ (mm−1) | 0.09 |
Crystal size (mm) | 0.50 × 0.35 × 0.30 |
Data collection | |
Diffractometer | Syntex P21 diffractometer |
Absorption correction | – |
No. of measured, independent and observed [I > 2σ(I)] reflections | 3271, 3271, 2513 |
Rint | 0.000 |
(sin θ/λ)max (Å−1) | 0.630 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.047, 0.133, 1.10 |
No. of reflections | 3271 |
No. of parameters | 226 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.17, −0.23 |
Computer programs: P21 software (Syntex, 1973), P21 software, XP21 (Pavelčík, 1987), SHELXS97 (Sheldrick, 1997), SHELXL97 (Sheldrick, 1997), ORTEPII (Johnson, 1976), SHELXL97.
N1—C2 | 1.350 (3) | C9—O10 | 1.399 (2) |
N1—C9 | 1.439 (3) | O10—C11 | 1.439 (2) |
N1—C18 | 1.443 (3) | C11—C19 | 1.497 (3) |
C2—O2 | 1.217 (2) | C11—C12 | 1.514 (3) |
C2—C3 | 1.473 (3) | C12—C17 | 1.395 (3) |
C3—C8 | 1.376 (3) | C17—C18 | 1.497 (3) |
C8—C9 | 1.492 (3) | ||
C2—N1—C9 | 113.90 (16) | N1—C2—C3 | 106.04 (17) |
C2—N1—C18 | 124.57 (17) | O10—C9—N1 | 113.94 (16) |
C9—N1—C18 | 121.53 (16) | O10—C9—C8 | 109.38 (16) |
O2—C2—N1 | 126.21 (19) | N1—C9—C8 | 102.13 (16) |
O2—C2—C3 | 127.74 (19) | C9—O10—C11 | 114.19 (14) |
C18—N1—C9—O10 | −60.7 (2) | C11—C12—C17—C18 | −1.1 (3) |
N1—C9—O10—C11 | 66.4 (2) | C9—N1—C18—C17 | 74.4 (2) |
C9—O10—C11—C12 | −88.91 (18) | C12—C17—C18—N1 | −59.1 (2) |
O10—C11—C12—C17 | 68.1 (2) | O10—C11—C19—C20 | 10.5 (2) |
The work presented here is part of our continuing study aimed at designing modulators of hormonal/neurotransmitter systems as potential drugs to treat neuronal and cardiovascular disorders. Based on the recent pharmacophore/receptor model of the benzodiazepine (BDZ) receptor subtype located in the central nervous system (CNS; Huang et al., 2000), we designed the title compound, (IV), as a potential anxiolytic agent. Synthesis of (IV) was achieved by a sequential reaction (Scheme) and led to a 5:1 diastereomeric (racemic) mixture of cis and trans isomers, (IVa) and (IVb), respectively. In order to establish the detailed stereochemistry of the two diastereomers, viz. the spatial relationship between the putative pharmacophoric elements (phenyl rings and the two O atoms), which is indispensable for future molecular-modeling studies, the crystal structure determination of (IVa) and (IVb) has been undertaken. In this communication, we report on the structure of the cis isomer, (IVa). \sch
The molecular structure of (IVa) is shown in Fig. 1. As expected, the isoindolinone ring is nearly planar, with an average deviation of the ring atoms from the least-squares plane of 0.016 (3) Å. As shown in Table 1, the N1—C2 bond is much shorter than the N1—C9 and N1—C18 bonds. Moreover, the N1 atom is sp2 hybridized, as evidenced by the sum of the valence angles at this atom [360.0 (2)°]. These data are consistent with conjugation of the lone-pair electrons on N1 with the adjacent carbonyl function, similar to what is observed for amides. Indeed, the N—C bond lengths at N1 are in good agreement with the comparable bond lengths found in cyclic amino acids (Benedetti et al., 1983). A similar pattern of bond distances and angles within the isoindolinone moiety has been found in other compounds incorporating this molecular fragment (Barrett et al., 1995; McNab et al., 1997; Khan et al., 1998), as revealed by a search of the Cambridge Structural Database (Allen & Kennard, 1993).
As mentioned above, the main purpose of the present structure determination was to establish the relative three-dimensional disposition of the phenyl rings and the two O atoms (and the orientation of the lone pairs on them), which are assumed to constitute the interaction pharmacophore responsible for binding of the compound to the CNS-subtype of the BDZ receptor. Obviously, the disposition of these structural elements depends primarily on the conformation of the seven-membered oxazepine ring, which is the most flexible part of the molecule. A comparison of the endocyclic torsion angles for the oxazepine ring (Table 1) reveals that it adopts a distorted chair conformation, with an approximate mirror plane passing through C9 and the midpoint of the C12—C17 bond; N1, C18, O10 and C11 lie in the plane and C9, C12 and C17 are, respectively, 0.640 (2), -1.115 (2) and -1.146 (2) Å out of it. The puckering parameters according to Cremer & Pople (1975) are q2 = 0.465 (2) Å, ϕ2 = -111.5 (3)°, q3 = 0.624 (3) Å and ϕ3 = 29.6 (2)° for the sequence N1/C9/O10/C11/C12/C17/C18. The deviation from ideal Cs symmetry described by the asymmetry parameter ΔCs(C9) is 0.046 (1) (Nardelli, 1983).
As a result of the relatively severe puckering of the central oxazepine ring, the molecule as a whole is non-planar: the two (planar) terminal segments of the molecule (the isoindoline and the benzene ring fused to the oxazepine moiety) are inclined at an angle of 67.7 (1)° to each other. The phenyl group at C11 is in a pseudo-equatorial orientation and is rotated around the C11—C19 bond in such a manner that the O10—C11—C19—C20 torsion angle is 10.5 (2)°.