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The molecules of the title compound, 4-benzyl-1,3-oxazolidene-2,5-dione, C10H9NO3, are linked by intermolecular hydrogen bonds between the imino group of the five-membered ring and an adjacent carbonyl O-atom, along the c axis. The benzyl groups are stacked in a layer and the five-membered rings are arranged in another layer sandwiched by the benzyl group layer. This sandwich structure should explain the high polymerizability of the title compound in the solid state.
Supporting information
CCDC reference: 144641
Compound (I) was obtained from L-phenylalanine by phosgenation in
tetrahydrofuran with trichloromethyl chloroformate, using a method similar to
that used for the other NCAs (Kanazawa & Kawai, 1980). The reaction product
was purified by recrystallization from a solution in a mixture of ethyl
acetate and hexane. Crystals for X-ray analysis were obtained from a solution
in ethyl acetate with hexane vapor at about 283 K, avoiding contamination by
moisture.
As the absolute structure could not be determined reliably from the Flack
parameter and since it is known from the synthesis, the Friedel pairs were
merged. Extinction conditions indicated that the space group is
P212121. H atoms were located at geometrically calculated
positions and were fixed in refinement, except for H1 attatched to N1, which
was freely refined.
Data collection: PROCESS (Rigaku, 1996); cell refinement: PROCESS; data reduction: TEXSAN (Molecular Structure Corporation, 1999); program(s) used to solve structure: SIR92 (Altomare et al., 1994); program(s) used to refine structure: TEXSAN; molecular graphics: ORTEPII (Johnson, 1976); software used to prepare material for publication: TEXSAN.
Crystal data top
C10H9NO3 | Dx = 1.353 Mg m−3 |
Mr = 191.19 | Mo Kα radiation, λ = 0.7107 Å |
Orthorhombic, P212121 | Cell parameters from 1440 reflections |
a = 10.881 (2) Å | θ = 1.3–29.0° |
b = 15.753 (2) Å | µ = 0.10 mm−1 |
c = 5.4764 (5) Å | T = 293 K |
V = 938.7 (2) Å3 | Needle, colourless |
Z = 4 | 0.25 × 0.15 × 0.15 mm |
Data collection top
Rigaku RAXIS-IV Imaging Plate diffractometer | Rint = 0.059 |
Detector resolution: 10 pixels mm-1 | θmax = 29.0° |
ω scans | h = −14→14 |
6823 measured reflections | k = −21→21 |
1427 independent reflections | l = −7→7 |
1032 reflections with F2 > 2σ(F2) | |
Refinement top
Refinement on F2 | w = 1/[σ2(Fo2) + {0.067[Max(Fo2,0) + 2Fc2]/3}2] |
R[F2 > 2σ(F2)] = 0.055 | (Δ/σ)max < 0.001 |
wR(F2) = 0.158 | Δρmax = 0.21 e Å−3 |
S = 1.25 | Δρmin = −0.17 e Å−3 |
1427 reflections | Extinction correction: Zachariasen (1967) type 2 Gaussian isotropic |
133 parameters | Extinction coefficient: 0.075 (9) |
H atoms treated by a mixture of independent and constrained refinement | |
Crystal data top
C10H9NO3 | V = 938.7 (2) Å3 |
Mr = 191.19 | Z = 4 |
Orthorhombic, P212121 | Mo Kα radiation |
a = 10.881 (2) Å | µ = 0.10 mm−1 |
b = 15.753 (2) Å | T = 293 K |
c = 5.4764 (5) Å | 0.25 × 0.15 × 0.15 mm |
Data collection top
Rigaku RAXIS-IV Imaging Plate diffractometer | 1032 reflections with F2 > 2σ(F2) |
6823 measured reflections | Rint = 0.059 |
1427 independent reflections | |
Refinement top
R[F2 > 2σ(F2)] = 0.055 | 133 parameters |
wR(F2) = 0.158 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.25 | Δρmax = 0.21 e Å−3 |
1427 reflections | Δρmin = −0.17 e Å−3 |
Special details top
Refinement. Refinement using reflections with F2 > -10.0 σ(F2). The
weighted R-factor (wR) and goodness of fit (S) are based
on F2. R-factor (gt) are based on F. The threshold
expression of F2 > 2.0 σ(F2) is used only for calculating
R-factor (gt). |
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top | x | y | z | Uiso*/Ueq | |
O1 | 1.1488 (2) | −0.0071 (1) | −0.0384 (3) | 0.0855 (6) | |
O2 | 0.9531 (1) | 0.0230 (1) | 0.0607 (3) | 0.0640 (4) | |
O3 | 0.7821 (2) | 0.0600 (1) | 0.2637 (4) | 0.0870 (6) | |
N1 | 1.0946 (2) | 0.0406 (1) | 0.3457 (3) | 0.0624 (5) | |
C1 | 1.0772 (2) | 0.0163 (2) | 0.1157 (4) | 0.0593 (5) | |
C2 | 0.8905 (2) | 0.0501 (1) | 0.2637 (4) | 0.0604 (5) | |
C3 | 0.9816 (3) | 0.0642 (1) | 0.4667 (4) | 0.0641 (5) | |
C4 | 0.9762 (3) | 0.1560 (2) | 0.5641 (4) | 0.0895 (8) | |
C5 | 0.9914 (3) | 0.2227 (1) | 0.3679 (5) | 0.0809 (7) | |
C6 | 0.8899 (3) | 0.2577 (2) | 0.2521 (7) | 0.1007 (10) | |
C7 | 0.9054 (4) | 0.3163 (2) | 0.0613 (8) | 0.107 (1) | |
C8 | 1.0181 (4) | 0.3393 (2) | −0.0105 (6) | 0.1009 (9) | |
C9 | 1.1172 (5) | 0.3065 (2) | 0.1027 (9) | 0.122 (1) | |
C10 | 1.1053 (4) | 0.2482 (2) | 0.2907 (8) | 0.1054 (10) | |
H1 | 1.172 (2) | 0.038 (2) | 0.407 (5) | 0.070 (7)* | |
H2 | 0.9656 | 0.0253 | 0.5979 | 0.0751* | |
H3 | 0.8986 | 0.1636 | 0.6421 | 0.1119* | |
H4 | 1.0397 | 0.1626 | 0.6828 | 0.1119* | |
H5 | 0.8089 | 0.2407 | 0.3070 | 0.1179* | |
H6 | 0.8317 | 0.3389 | −0.0213 | 0.1275* | |
H7 | 1.0295 | 0.3782 | −0.1436 | 0.1179* | |
H8 | 1.1965 | 0.3262 | 0.0544 | 0.1421* | |
H9 | 1.1794 | 0.2239 | 0.3640 | 0.1260* | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
O1 | 0.0680 (10) | 0.123 (1) | 0.0659 (9) | 0.011 (1) | 0.0144 (8) | −0.015 (1) |
O2 | 0.0559 (8) | 0.095 (1) | 0.0409 (6) | −0.0006 (8) | −0.0030 (6) | 0.0010 (7) |
O3 | 0.0644 (9) | 0.102 (1) | 0.095 (1) | 0.0106 (9) | 0.0174 (9) | 0.020 (1) |
N1 | 0.066 (1) | 0.072 (1) | 0.0493 (8) | 0.0063 (10) | −0.0139 (8) | 0.0002 (8) |
C1 | 0.0579 (10) | 0.074 (1) | 0.0459 (8) | 0.0028 (10) | 0.0002 (8) | 0.0008 (9) |
C2 | 0.0652 (10) | 0.064 (1) | 0.0520 (9) | 0.004 (1) | 0.0117 (8) | 0.0115 (10) |
C3 | 0.085 (1) | 0.065 (1) | 0.0419 (8) | 0.008 (1) | 0.0078 (9) | 0.0067 (9) |
C4 | 0.151 (3) | 0.069 (1) | 0.0480 (9) | 0.005 (2) | 0.011 (2) | −0.0056 (9) |
C5 | 0.128 (2) | 0.056 (1) | 0.059 (1) | −0.002 (1) | 0.006 (1) | −0.0099 (9) |
C6 | 0.122 (2) | 0.074 (1) | 0.106 (2) | 0.031 (2) | 0.028 (2) | 0.014 (2) |
C7 | 0.146 (2) | 0.067 (1) | 0.109 (2) | 0.026 (2) | 0.000 (3) | 0.017 (2) |
C8 | 0.166 (3) | 0.056 (1) | 0.080 (2) | −0.017 (2) | 0.007 (2) | 0.005 (1) |
C9 | 0.142 (3) | 0.094 (2) | 0.130 (3) | −0.045 (2) | −0.011 (3) | 0.031 (2) |
C10 | 0.116 (2) | 0.092 (2) | 0.108 (2) | −0.030 (2) | −0.033 (2) | 0.015 (2) |
Geometric parameters (Å, º) top
O1—C1 | 1.207 (3) | C4—C5 | 1.513 (4) |
O2—C1 | 1.388 (3) | C5—C6 | 1.390 (5) |
O2—C2 | 1.372 (3) | C5—C10 | 1.369 (5) |
O3—C2 | 1.187 (4) | C6—C7 | 1.406 (6) |
N1—C1 | 1.329 (3) | C7—C8 | 1.335 (7) |
N1—C3 | 1.447 (4) | C8—C9 | 1.346 (7) |
C2—C3 | 1.508 (4) | C9—C10 | 1.387 (7) |
C3—C4 | 1.542 (4) | | |
| | | |
O1···N1i | 2.911 (3) | O2···C4ii | 3.441 (3) |
O1···C3ii | 3.451 (4) | O3···O3v | 3.400 (3) |
O1···N1ii | 3.504 (3) | O3···O3iv | 3.400 (3) |
O1···O1iii | 3.522 (3) | O3···C9vi | 3.416 (5) |
O1···O1i | 3.522 (3) | O3···C8vi | 3.565 (5) |
O1···C1i | 3.535 (3) | N1···C8vii | 3.518 (4) |
O2···O3iv | 3.303 (3) | N1···C7vii | 3.570 (4) |
O2···C3ii | 3.331 (3) | C3···C8vii | 3.551 (4) |
| | | |
C1—O2—C2 | 109.4 (2) | C2—C3—C4 | 111.6 (2) |
C1—N1—C3 | 112.7 (2) | C3—C4—C5 | 113.7 (2) |
O1—C1—O2 | 119.9 (2) | C4—C5—C6 | 120.8 (3) |
O1—C1—N1 | 131.2 (3) | C4—C5—C10 | 121.5 (3) |
O2—C1—N1 | 108.9 (2) | C6—C5—C10 | 117.6 (3) |
O2—C2—O3 | 122.3 (3) | C5—C6—C7 | 120.1 (4) |
O2—C2—C3 | 108.4 (2) | C6—C7—C8 | 120.6 (4) |
O3—C2—C3 | 129.3 (3) | C7—C8—C9 | 119.7 (3) |
N1—C3—C2 | 100.6 (2) | C8—C9—C10 | 121.4 (4) |
N1—C3—C4 | 115.6 (3) | C5—C10—C9 | 120.5 (4) |
| | | |
O1—C1—O2—C2 | 179.7 (3) | C1—N1—C3—C4 | −120.7 (3) |
O1—C1—N1—C3 | 179.7 (3) | C2—C3—C4—C5 | −54.3 (4) |
O2—C1—N1—C3 | 1.2 (3) | C3—C4—C5—C6 | 92.7 (4) |
O2—C2—C3—N1 | −0.7 (3) | C3—C4—C5—C10 | −84.3 (4) |
O2—C2—C3—C4 | 122.5 (2) | C4—C5—C6—C7 | −176.7 (3) |
O3—C2—O2—C1 | −179.3 (3) | C4—C5—C10—C9 | 177.0 (4) |
O3—C2—C3—N1 | −179.9 (3) | C5—C6—C7—C8 | 0.0 (6) |
O3—C2—C3—C4 | −56.7 (4) | C5—C10—C9—C8 | −0.7 (7) |
N1—C1—O2—C2 | −1.7 (3) | C6—C5—C10—C9 | −0.1 (6) |
N1—C3—C4—C5 | 59.9 (4) | C6—C7—C8—C9 | −0.7 (7) |
C1—O2—C2—C3 | 1.4 (3) | C7—C6—C5—C10 | 0.4 (5) |
C1—N1—C3—C2 | −0.3 (3) | C7—C8—C9—C10 | 1.1 (7) |
Symmetry codes: (i) −x+5/2, −y, z−1/2; (ii) x, y, z−1; (iii) −x+5/2, −y, z+1/2; (iv) −x+3/2, −y, z−1/2; (v) −x+3/2, −y, z+1/2; (vi) x−1/2, −y+1/2, −z; (vii) −x+2, y−1/2, −z+1/2. |
Hydrogen-bond geometry (Å, º) top
D—H···A | D—H | H···A | D···A | D—H···A |
N1—H1···O1 | 0.91 (2) | 2.03 (2) | 2.912 (2) | 162 (2) |
Experimental details
Crystal data |
Chemical formula | C10H9NO3 |
Mr | 191.19 |
Crystal system, space group | Orthorhombic, P212121 |
Temperature (K) | 293 |
a, b, c (Å) | 10.881 (2), 15.753 (2), 5.4764 (5) |
V (Å3) | 938.7 (2) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 0.10 |
Crystal size (mm) | 0.25 × 0.15 × 0.15 |
|
Data collection |
Diffractometer | Rigaku RAXIS-IV Imaging Plate diffractometer |
Absorption correction | – |
No. of measured, independent and observed [F2 > 2σ(F2)] reflections | 6823, 1427, 1032 |
Rint | 0.059 |
(sin θ/λ)max (Å−1) | 0.683 |
|
Refinement |
R[F2 > 2σ(F2)], wR(F2), S | 0.055, 0.158, 1.25 |
No. of reflections | 1427 |
No. of parameters | 133 |
No. of restraints | ? |
H-atom treatment | H atoms treated by a mixture of independent and constrained refinement |
Δρmax, Δρmin (e Å−3) | 0.21, −0.17 |
Selected geometric parameters (Å, º) topO1—C1 | 1.207 (3) | N1—C3 | 1.447 (4) |
O2—C1 | 1.388 (3) | C2—C3 | 1.508 (4) |
O2—C2 | 1.372 (3) | C3—C4 | 1.542 (4) |
O3—C2 | 1.187 (4) | C4—C5 | 1.513 (4) |
N1—C1 | 1.329 (3) | | |
| | | |
C1—O2—C2 | 109.4 (2) | O2—C2—O3 | 122.3 (3) |
C1—N1—C3 | 112.7 (2) | O2—C2—C3 | 108.4 (2) |
O1—C1—O2 | 119.9 (2) | O3—C2—C3 | 129.3 (3) |
O1—C1—N1 | 131.2 (3) | N1—C3—C2 | 100.6 (2) |
O2—C1—N1 | 108.9 (2) | | |
| | | |
O1—C1—O2—C2 | 179.7 (3) | O3—C2—C3—N1 | −179.9 (3) |
O1—C1—N1—C3 | 179.7 (3) | O3—C2—C3—C4 | −56.7 (4) |
O2—C1—N1—C3 | 1.2 (3) | C1—N1—C3—C2 | −0.3 (3) |
O2—C2—C3—N1 | −0.7 (3) | C1—N1—C3—C4 | −120.7 (3) |
O3—C2—O2—C1 | −179.3 (3) | | |
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N-Carboxy anhydrides (NCAs) of amino acids are crystalline compounds and are usually polymerized in solution to prepare polypeptides (Bamford et al., 1956). Several amino acid NCA crystals are known to be decomposed or polymerized by moisture. When butylamine is added to NCA crystals immersed in non-solvents, polymerization takes place in the solid state. The authors studied this solid-state polymerization and found the polymerizability of NCAs was extremely dependent on the kind of amino acid used. The crystal structures of amino acid NCAs have not been studied since a very early report by Lechus (1906).
The present authors determined the crystal structures of glycine NCA (Kanazawa et al. 1976a) and L-alanine NCA (Kanazawa et al. 1976b) and discussed their polymerizability with reference to the crystal structure (Kanazawa & Kawai, 1980). In addition, the crystal structures of γ-benzyl-L-glutamate NCA (Kanazawa et al., 1978a), L-leucine NCA (Kanazawa et al., 1978b), L-valine NCA (Kanazawa & Ohashi, 1984), DL-valine NCA (Takenaka et al., 1994) and DL-phenylalanine NCA (Kanazawa et al., 1997) have been determined. The polymerization of L-leucine NCA, which was the most reactive in the solid state among the examined NCAs, has been studied in detail (Kanazawa et al., 1982; Kanazawa, 1992a,b). Recently, the title compound, (I), was found to be still more reactive than any other NCAs in the solid state, although it gave almost no reactivity in solution (Kanazawa, 1997). As compound (I) is very sensitive to moisture in air, it often polymerizes spontaneously in the crystallization process. Thus, crystals suitable for the present X-ray work were obtained after many attempts. This paper describes the crystal structure of compound (I). \scheme
Intermolecular N1—H1···O1(5/2 - x, -y, 1/2 + z) hydrogen bonds are formed along the c axis. Hydrogen bond lengths and angles are N1···O1 2.912 (2) Å, H1···O1 2.03 (2) Å, and N1—H1···O1 162 (2)°. From Fig. 2, it can be seen that the benzyl groups are in a layer and the benzene rings seem almost parallel to each other. The five-membered NCA rings are packed in another layer and these two layers are aligned alternately. The five-membered rings could easily react with one another within the layer. In fact, electron microscopy suggests that the polymerization mainly proceeds along the c axis. This sandwich structure is one of the preferred requirements for high reactivity in the solid state (Kanazawa, 1992a). In the crystal of DL-phenylalanine NCA, a sandwich structure composed of D and L molecules was observed (Kanazawa et al., 1997), and the crystal was also reactive in the solid state.