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Benzyl N-[8-(4,4-dimethyl-5-oxo-4,5-dihydrooxazol-2-yl)-2,5,5,8-tetra­methyl-3,6-dioxo-4,7-diazanon-2-yl]­carbamate, C24H34N4O6, an oxazol-5(4H)-one from N-α-benzyloxycarbonyl-(Aib)4-OH (Aib = α-amino­isobutyryl) represents the longest peptide oxazolone so far characterized by X-ray diffraction. The overall geometry of the oxazolone ring compares well with literature data. The Aib(1) and Aib(2) residues are folded into a type III β-bend, while the conformation adopted by Aib(3), preceding the oxazolone moiety, is semi-extended. The disposition of the oxazolone ring relative to the preceding residue is stabilized by C—­H...N and C—H...O intramolecular interactions.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270100003413/ln1097sup1.cif
Contains datablocks I, global

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S0108270100003413/ln1097Isup2.hkl
Contains datablock I

Computing details top

Data collection: FEBO (Belletti, 1993); cell refinement: FEBO; data reduction: FEBO; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: PLATON (Spek, 1998); software used to prepare material for publication: SHELXL97.

benzyl N-[8-(4,4-dimethyl-5-oxooxazol-2-yl)-2,5,5,8-tetramethyl-3,6-dioxo-4,7- diazanon-2-yl]carbamate top
Crystal data top
C24H34N4O6Dx = 1.203 Mg m3
Mr = 474.55Melting point: 430 K K
Monoclinic, P21/cMo Kα radiation, λ = 0.71073 Å
a = 9.324 (2) ÅCell parameters from 48 reflections
b = 25.149 (3) Åθ = 7–12°
c = 11.753 (2) ŵ = 0.09 mm1
β = 108.00 (5)°T = 293 K
V = 2621.1 (8) Å3Prism, colourless
Z = 40.6 × 0.4 × 0.4 mm
F(000) = 1016
Data collection top
Philips PW1100
diffractometer
Rint = 0.020
Radiation source: fine-focus sealed tubeθmax = 24.7°, θmin = 4.4°
Graphite monochromatorh = 1010
θ–2θ scansk = 029
4649 measured reflectionsl = 013
4427 independent reflections3 standard reflections every 50 reflections
3058 reflections with I > 2σ(I) intensity decay: none
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.043Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.132H-atom parameters constrained
S = 1.00 w = 1/[σ2(Fo2) + (0.0835P)2]
where P = (Fo2 + 2Fc2)/3
4427 reflections(Δ/σ)max = 0.021
315 parametersΔρmax = 0.15 e Å3
3 restraintsΔρmin = 0.22 e Å3
Special details top

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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
C010.0368 (3)0.43196 (7)0.03121 (17)0.0664 (6)
C020.1106 (4)0.44277 (10)0.1132 (2)0.1002 (9)
H020.05510.44930.19250.120*
C030.2652 (6)0.44402 (13)0.0797 (4)0.1282 (13)
H030.31310.45230.13610.154*
C040.3505 (4)0.43322 (11)0.0365 (4)0.1110 (10)
H040.45530.43400.05860.133*
C050.2793 (3)0.42144 (10)0.1184 (2)0.0908 (7)
H050.33510.41370.19690.109*
C060.1249 (3)0.42101 (9)0.08467 (18)0.0730 (6)
H060.07770.41310.14170.088*
C070.1310 (3)0.43294 (8)0.0658 (2)0.0888 (8)
H07A0.16180.44950.00260.107*
H07B0.17070.45410.13780.107*
OU0.19353 (17)0.37942 (5)0.08716 (11)0.0736 (4)
C00.2332 (2)0.35644 (7)0.00284 (15)0.0554 (5)
O00.22556 (16)0.37858 (5)0.09709 (11)0.0710 (4)
N10.27910 (16)0.30639 (5)0.02583 (11)0.0495 (4)
H10.27360.29360.09220.059*
C1A0.33805 (18)0.27258 (7)0.05049 (14)0.0489 (4)
C1B10.3704 (2)0.21860 (8)0.01060 (17)0.0655 (5)
H1B10.44740.22230.08640.098*
H1B20.40420.19440.03900.098*
H1B30.28020.20500.02290.098*
C1B20.4812 (2)0.29611 (10)0.0676 (2)0.0793 (6)
H1B40.45740.32900.11060.119*
H1B50.52220.27160.11200.119*
H1B60.55400.30250.00920.119*
C10.21910 (19)0.26420 (6)0.17437 (14)0.0459 (4)
O10.25888 (15)0.25267 (6)0.26155 (11)0.0661 (4)
N20.07483 (15)0.26892 (5)0.17929 (11)0.0451 (3)
H20.05570.27610.11390.054*
C2A0.05393 (19)0.26267 (7)0.28876 (14)0.0494 (4)
C2B10.1952 (2)0.27702 (9)0.25552 (18)0.0683 (5)
H2B10.20500.25330.19440.102*
H2B20.28230.27390.32490.102*
H2B30.18690.31290.22630.102*
C2B20.0652 (2)0.20610 (8)0.33699 (18)0.0700 (6)
H2B40.02810.19650.35020.105*
H2B50.14580.20400.41110.105*
H2B60.08490.18210.28000.105*
C20.0453 (2)0.30334 (7)0.38514 (14)0.0541 (4)
O20.11412 (18)0.29478 (6)0.49065 (11)0.0781 (5)
N30.02424 (16)0.34978 (6)0.34785 (12)0.0545 (4)
H30.08020.35250.27470.065*
C3A0.00871 (19)0.39639 (7)0.42708 (14)0.0526 (4)
C3B10.0935 (2)0.38971 (9)0.51831 (18)0.0719 (6)
H3B10.19980.38750.47740.108*
H3B20.07360.41970.57150.108*
H3B30.06050.35770.56340.108*
C3B20.0678 (3)0.44463 (8)0.34730 (18)0.0722 (6)
H3B40.00470.45110.29790.108*
H3B50.06680.47520.39640.108*
H3B60.16910.43790.29760.108*
C30.15714 (19)0.40438 (7)0.49153 (14)0.0493 (4)
N40.22054 (16)0.41749 (6)0.59869 (12)0.0552 (4)
C4A0.3832 (2)0.41893 (8)0.61541 (17)0.0624 (5)
C4B10.4596 (3)0.37348 (11)0.7001 (2)0.0917 (8)
H4B10.44820.37940.77760.137*
H4B20.56490.37240.70710.137*
H4B30.41340.34030.66860.137*
C4B20.4510 (3)0.47288 (11)0.6589 (3)0.0954 (8)
H4B40.39730.50000.60490.143*
H4B50.55520.47330.66220.143*
H4B60.44350.47960.73730.143*
C40.3931 (2)0.40755 (8)0.49141 (18)0.0628 (5)
O30.24888 (14)0.39839 (5)0.41824 (10)0.0612 (3)
O40.49883 (18)0.40632 (7)0.45418 (15)0.0864 (5)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
C010.1006 (17)0.0397 (10)0.0556 (11)0.0099 (10)0.0195 (11)0.0006 (8)
C020.172 (3)0.0730 (16)0.0660 (15)0.0173 (18)0.0520 (18)0.0021 (12)
C030.186 (4)0.098 (2)0.149 (3)0.007 (2)0.122 (3)0.005 (2)
C040.105 (2)0.0824 (19)0.166 (3)0.0012 (16)0.071 (2)0.002 (2)
C050.0877 (18)0.0897 (18)0.0955 (17)0.0049 (14)0.0288 (15)0.0088 (13)
C060.0862 (16)0.0753 (14)0.0601 (12)0.0088 (11)0.0265 (11)0.0059 (10)
C070.111 (2)0.0461 (12)0.0870 (16)0.0124 (12)0.0021 (14)0.0169 (11)
OU0.1014 (11)0.0525 (8)0.0535 (8)0.0163 (7)0.0043 (7)0.0058 (6)
C00.0621 (11)0.0471 (10)0.0433 (9)0.0071 (8)0.0039 (8)0.0013 (8)
O00.0910 (10)0.0538 (8)0.0555 (8)0.0089 (7)0.0039 (7)0.0129 (6)
N10.0605 (9)0.0459 (8)0.0360 (7)0.0002 (6)0.0057 (6)0.0035 (6)
C1A0.0438 (9)0.0538 (10)0.0457 (9)0.0018 (7)0.0088 (7)0.0028 (7)
C1B10.0680 (13)0.0635 (12)0.0602 (11)0.0178 (10)0.0129 (9)0.0096 (9)
C1B20.0538 (12)0.1050 (18)0.0762 (14)0.0183 (11)0.0160 (10)0.0003 (12)
C10.0513 (10)0.0412 (9)0.0431 (9)0.0022 (7)0.0113 (7)0.0019 (7)
O10.0730 (9)0.0796 (9)0.0504 (7)0.0060 (7)0.0260 (6)0.0120 (6)
N20.0463 (8)0.0501 (8)0.0348 (7)0.0014 (6)0.0066 (6)0.0009 (6)
C2A0.0498 (10)0.0472 (10)0.0413 (9)0.0051 (7)0.0004 (7)0.0005 (7)
C2B10.0501 (11)0.0804 (14)0.0638 (12)0.0045 (10)0.0022 (9)0.0087 (10)
C2B20.0773 (14)0.0524 (11)0.0640 (12)0.0134 (10)0.0021 (10)0.0031 (9)
C20.0601 (11)0.0521 (10)0.0403 (9)0.0027 (8)0.0013 (8)0.0005 (8)
O20.1074 (11)0.0687 (9)0.0393 (7)0.0173 (8)0.0047 (7)0.0019 (6)
N30.0666 (10)0.0474 (8)0.0378 (7)0.0055 (7)0.0011 (6)0.0046 (6)
C3A0.0572 (11)0.0501 (10)0.0446 (9)0.0010 (8)0.0073 (8)0.0095 (7)
C3B10.0649 (13)0.0821 (15)0.0704 (13)0.0102 (11)0.0235 (10)0.0190 (11)
C3B20.0885 (15)0.0526 (11)0.0623 (12)0.0160 (10)0.0041 (11)0.0094 (9)
C30.0594 (11)0.0461 (10)0.0428 (9)0.0029 (8)0.0162 (8)0.0042 (7)
N40.0575 (9)0.0581 (9)0.0457 (8)0.0037 (7)0.0097 (7)0.0081 (7)
C4A0.0554 (11)0.0664 (12)0.0589 (11)0.0028 (9)0.0080 (9)0.0071 (9)
C4B10.0844 (16)0.112 (2)0.0667 (14)0.0209 (14)0.0066 (12)0.0070 (13)
C4B20.0806 (16)0.0981 (18)0.1058 (18)0.0279 (14)0.0263 (14)0.0344 (15)
C40.0658 (13)0.0560 (11)0.0694 (12)0.0023 (9)0.0251 (10)0.0024 (9)
O30.0664 (8)0.0707 (8)0.0489 (7)0.0021 (7)0.0213 (6)0.0057 (6)
O40.0754 (10)0.0940 (12)0.1024 (12)0.0049 (8)0.0458 (9)0.0041 (9)
Geometric parameters (Å, º) top
C01—C021.374 (3)C2A—C2B11.528 (3)
C01—C061.384 (3)C2A—C2B21.523 (2)
C01—C071.490 (3)C2A—C21.547 (2)
C02—C031.373 (5)C2—O21.226 (2)
C03—C041.378 (5)C2—N31.342 (2)
C04—C051.360 (4)N3—C3A1.476 (2)
C05—C061.370 (3)C3A—C31.510 (3)
C07—OU1.457 (2)C3A—C3B11.525 (3)
OU—C01.353 (2)C3A—C3B21.528 (3)
C0—O01.222 (2)C3—N41.259 (2)
C0—N11.339 (2)C3—O31.397 (2)
N1—C1A1.461 (2)N4—C4A1.468 (2)
C1A—C1B11.522 (2)C4A—C41.516 (3)
C1A—C1B21.529 (3)C4A—C4B21.518 (3)
C1A—C11.548 (2)C4A—C4B11.539 (3)
C1—O11.227 (2)C4—O41.196 (2)
C1—N21.334 (2)C4—O31.374 (2)
N2—C2A1.472 (2)
C02—C01—C06117.1 (2)N2—C2A—C2110.89 (13)
C02—C01—C07121.1 (2)C2B1—C2A—C2105.97 (15)
C06—C01—C07121.7 (2)C2B2—C2A—C2111.00 (14)
C03—C02—C01120.8 (3)O2—C2—N3122.15 (16)
C04—C03—C02120.9 (3)O2—C2—C2A119.66 (15)
C03—C04—C05119.0 (3)N3—C2—C2A117.75 (14)
C06—C05—C04119.8 (3)C2—N3—C3A122.80 (13)
C05—C06—C01122.3 (2)N3—C3A—C3107.93 (14)
OU—C07—C01111.22 (18)N3—C3A—C3B1112.64 (15)
C0—OU—C07116.83 (16)C3—C3A—C3B1109.56 (14)
O0—C0—N1125.52 (18)N3—C3A—C3B2107.27 (13)
O0—C0—OU124.09 (17)C3—C3A—C3B2108.74 (16)
N1—C0—OU110.38 (15)C3B1—C3A—C3B2110.58 (16)
C0—N1—C1A122.99 (14)N4—C3—O3117.23 (15)
N1—C1A—C1B1106.68 (14)N4—C3—C3A128.92 (16)
N1—C1A—C1B2111.39 (16)O3—C3—C3A113.79 (14)
C1B1—C1A—C1B2110.68 (16)C3—N4—C4A106.66 (15)
N1—C1A—C1111.14 (13)N4—C4A—C4103.53 (16)
C1B1—C1A—C1107.60 (14)N4—C4A—C4B2111.88 (17)
C1B2—C1A—C1109.28 (15)C4—C4A—C4B2110.49 (19)
O1—C1—N2123.08 (16)N4—C4A—C4B1108.71 (17)
O1—C1—C1A120.25 (15)C4—C4A—C4B1109.18 (17)
N2—C1—C1A116.65 (14)C4B2—C4A—C4B1112.63 (19)
C1—N2—C2A124.59 (14)O4—C4—O3121.66 (19)
N2—C2A—C2B1106.61 (14)O4—C4—C4A131.2 (2)
N2—C2A—C2B2111.63 (14)O3—C4—C4A107.14 (17)
C2B1—C2A—C2B2110.50 (16)C4—O3—C3105.28 (14)
C06—C01—C02—C031.8 (3)C2B2—C2A—C2—O234.1 (2)
C07—C01—C02—C03177.2 (2)N2—C2A—C2—N328.7 (2)
C01—C02—C03—C041.6 (4)C2B1—C2A—C2—N386.64 (19)
C02—C03—C04—C050.3 (5)C2B2—C2A—C2—N3153.36 (17)
C03—C04—C05—C060.7 (4)O2—C2—N3—C3A7.6 (3)
C04—C05—C06—C010.4 (4)C2A—C2—N3—C3A164.78 (16)
C02—C01—C06—C050.9 (3)C2—N3—C3A—C348.4 (2)
C07—C01—C06—C05178.1 (2)C2—N3—C3A—C3B172.7 (2)
C02—C01—C07—OU99.8 (2)C2—N3—C3A—C3B2165.42 (18)
C06—C01—C07—OU81.2 (3)N3—C3A—C3—N4140.36 (18)
C01—C07—OU—C099.2 (2)C3B1—C3A—C3—N417.4 (3)
C07—OU—C0—O03.2 (3)C3B2—C3A—C3—N4103.6 (2)
C07—OU—C0—N1175.88 (16)N3—C3A—C3—O342.75 (19)
O0—C0—N1—C1A4.9 (3)C3B1—C3A—C3—O3165.72 (15)
OU—C0—N1—C1A176.01 (14)C3B2—C3A—C3—O373.31 (18)
C0—N1—C1A—C1B1177.49 (15)O3—C3—N4—C4A3.9 (2)
C0—N1—C1A—C1B261.6 (2)C3A—C3—N4—C4A179.27 (17)
C0—N1—C1A—C160.5 (2)C3—N4—C4A—C43.89 (19)
N1—C1A—C1—O1156.08 (15)C3—N4—C4A—C4B2122.88 (19)
C1B1—C1A—C1—O187.47 (19)C3—N4—C4A—C4B1112.11 (18)
C1B2—C1A—C1—O132.7 (2)N4—C4A—C4—O4176.5 (2)
N1—C1A—C1—N225.5 (2)C4B2—C4A—C4—O456.5 (3)
C1B1—C1A—C1—N290.98 (17)C4B1—C4A—C4—O467.8 (3)
C1B2—C1A—C1—N2148.80 (16)N4—C4A—C4—O32.73 (19)
O1—C1—N2—C2A2.0 (2)C4B2—C4A—C4—O3122.67 (19)
C1A—C1—N2—C2A179.64 (14)C4B1—C4A—C4—O3112.94 (19)
C1—N2—C2A—C2B1174.26 (15)O4—C4—O3—C3178.61 (18)
C1—N2—C2A—C2B265.0 (2)C4A—C4—O3—C30.69 (18)
C1—N2—C2A—C259.4 (2)N4—C3—O3—C42.1 (2)
N2—C2A—C2—O2158.77 (17)C3A—C3—O3—C4179.40 (14)
C2B1—C2A—C2—O285.9 (2)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N3—H3···O00.862.213.052 (2)167
N1—H1···O1i0.862.112.9627 (18)169
Symmetry code: (i) x, y+1/2, z1/2.
 

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