organic compounds
N-(Fluoren-9-ylmethoxycarbonyl)-L-isoleucine
aNational Institute for Materials Science, 3-13 Sakura, Tsukuba 305-0003, Japan, and bAdvanced Technology Support Division, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
*Correspondence e-mail: yamada.kazuhiko@nims.go.jp
In the N-(1-carboxy-2-methylbutyl)carbamate], C21H23NO4, the molecular plane of the O=C—NH—Cα unit is slightly pyramidalized. The N atom deviates from the basal plane by 0.2086 (12) Å. The O=C—N—Cα torsion angle is −17.2 (2)°, and the C—N and O=C bond lengths are 1.3675 (17) and 1.2122 (17) Å, respectively. Apparently the character of the sp2 hybrids of the molecular plane is, to some extent, reduced. The exhibits two intermolecular hydrogen bonds (O—H⋯O and N—H⋯O), in which the hydroxy O atom acts as a donor to the carbonyl group and an acceptor of the amide group, respectively.
of the title compound [systematic name fluoren-9-ylmethylRelated literature
For related literature on the crystal structures of N-α-fluoren-9-ylmethoxycarbonyl-protected amino acids, see: Valle et al. (1984); Yamada, Hashizume & Shimizu (2008); Yamada, Hashizume, Shimizu et al. (2008).
Experimental
Crystal data
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Data collection
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Refinement
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Data collection: CrystalClear (Rigaku/MSC, 2005); cell HKL-2000 (Otwinowski & Minor, 1997); data reduction: HKL-2000; program(s) used to solve structure: SIR2004 (Burla et al., 2005); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997); software used to prepare material for publication: SHELXL97.
Supporting information
10.1107/S1600536808021855/is2313sup1.cif
contains datablocks I, global. DOI:Structure factors: contains datablock I. DOI: 10.1107/S1600536808021855/is2313Isup2.hkl
A powdered sample of the title compound (I) was purchased from Wako Pure Chemical Industries, Ltd. (Osaka, Japan) and was used for the sample preparation without further purifications. Colorless needle like crystals of (I) were obtained from a saturated dichloromethane solution.
All H atoms were found on a difference map and were refined applying isotropic temperature factors.
The refined C—H, N—H or O—H dimensions are in the normal range: 0.975 (19)–1.015 (19) Å and 104.8 (10)–113.8 (11)° for C—H and C/N—C—H, respectively, for methyne; 0.942 (17)–1.01 (2) Å, 106.6 (13)–111.4 (12)° and 107.1 (18)–108.6 (14)° for C—H, C/O—C—H and H—C—H for methylene; 0.98 (3)–1.03 (3) Å, 109.5 (11)–112.8 (13)° and 104 (2)–111 (2)° for C—H, C—C—H and H—C—H, respectively, for methyl; 0.96 (2)–1.005 (19) Å and 117.7 (11)–123.1 (11)° for C—H and C—C—H, respectively, for aromatic; 0.88 (2) Å and 115.3 (12)–116.5 (12)° for N—H and C—N—H, respectively, for amide; 0.88 (2) Å and 108.7 (15)° for O—H and C—O—H, respectively, for hydroxyl. The range of the Uiso values of the H atoms are 0.016 (4)–0.067 (8) Å2.
In the absence of significant
effects, Friedel pairs have been merged.Data collection: CrystalClear (Rigaku/MSC, 2005); cell
HKL-2000 (Otwinowski & Minor, 1997); data reduction: HKL-2000 (Otwinowski & Minor, 1997); program(s) used to solve structure: SIR2004 (Burla et al., 2005); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).C21H23NO4 | F(000) = 752 |
Mr = 353.40 | Dx = 1.272 Mg m−3 |
Orthorhombic, P212121 | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: P 2ac 2ab | Cell parameters from 19896 reflections |
a = 5.3337 (2) Å | θ = 1.6–31.0° |
b = 13.6965 (4) Å | µ = 0.09 mm−1 |
c = 25.2514 (9) Å | T = 90 K |
V = 1844.70 (11) Å3 | Needle, colourless |
Z = 4 | 0.77 × 0.06 × 0.04 mm |
Rigaku AFC-8 with Saturn70 CCD diffractometer | 2993 reflections with I > 2σ(I) |
Radiation source: fine-focus rotating anode | Rint = 0.043 |
Confocal monochromator | θmax = 31.0°, θmin = 1.6° |
Detector resolution: 28.5714 pixels mm-1 | h = −7→7 |
ω scans | k = −13→19 |
19825 measured reflections | l = −36→36 |
3351 independent reflections |
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)] = 0.034 | Hydrogen site location: difference Fourier map |
wR(F2) = 0.084 | All H-atom parameters refined |
S = 1.03 | w = 1/[σ2(Fo2) + (0.0427P)2 + 0.2178P] where P = (Fo2 + 2Fc2)/3 |
3351 reflections | (Δ/σ)max < 0.001 |
327 parameters | Δρmax = 0.23 e Å−3 |
0 restraints | Δρmin = −0.18 e Å−3 |
C21H23NO4 | V = 1844.70 (11) Å3 |
Mr = 353.40 | Z = 4 |
Orthorhombic, P212121 | Mo Kα radiation |
a = 5.3337 (2) Å | µ = 0.09 mm−1 |
b = 13.6965 (4) Å | T = 90 K |
c = 25.2514 (9) Å | 0.77 × 0.06 × 0.04 mm |
Rigaku AFC-8 with Saturn70 CCD diffractometer | 2993 reflections with I > 2σ(I) |
19825 measured reflections | Rint = 0.043 |
3351 independent reflections |
R[F2 > 2σ(F2)] = 0.034 | 0 restraints |
wR(F2) = 0.084 | All H-atom parameters refined |
S = 1.03 | Δρmax = 0.23 e Å−3 |
3351 reflections | Δρmin = −0.18 e Å−3 |
327 parameters |
Experimental. All Friedel pairs were merged, and all f''s of containing atoms were set to zero. |
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 > 2σ(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 | −0.0029 (2) | 0.12876 (8) | 0.48657 (4) | 0.0236 (2) | |
H1H | −0.038 (4) | 0.1865 (16) | 0.5004 (8) | 0.040 (6)* | |
O2 | 0.3719 (2) | 0.19896 (8) | 0.47355 (4) | 0.0287 (2) | |
O3 | 0.4252 (2) | 0.06814 (8) | 0.34059 (4) | 0.0254 (2) | |
O4 | 0.83023 (19) | 0.09577 (8) | 0.36430 (4) | 0.0219 (2) | |
N1 | 0.5644 (2) | 0.03926 (9) | 0.42480 (4) | 0.0201 (2) | |
H1N | 0.683 (4) | 0.0588 (14) | 0.4465 (7) | 0.028 (5)* | |
C1 | 0.3145 (3) | 0.03122 (10) | 0.44681 (5) | 0.0198 (3) | |
H1 | 0.201 (4) | 0.0187 (13) | 0.4152 (7) | 0.029 (5)* | |
C2 | 0.2942 (3) | −0.05077 (10) | 0.48868 (5) | 0.0221 (3) | |
H2 | 0.124 (4) | −0.0497 (14) | 0.5026 (7) | 0.025 (5)* | |
C3 | 0.4615 (4) | −0.03098 (13) | 0.53677 (6) | 0.0322 (4) | |
H3A | 0.641 (5) | −0.0353 (16) | 0.5239 (9) | 0.045 (6)* | |
H3B | 0.433 (4) | 0.0382 (16) | 0.5491 (8) | 0.043 (6)* | |
C4 | 0.4141 (5) | −0.10079 (16) | 0.58280 (7) | 0.0429 (5) | |
H4A | 0.524 (5) | −0.0821 (19) | 0.6146 (10) | 0.063 (7)* | |
H4B | 0.449 (5) | −0.1707 (17) | 0.5734 (9) | 0.050 (6)* | |
H4C | 0.237 (6) | −0.1000 (19) | 0.5925 (10) | 0.067 (8)* | |
C5 | 0.3466 (4) | −0.14964 (12) | 0.46325 (7) | 0.0321 (4) | |
H5A | 0.235 (4) | −0.1587 (15) | 0.4308 (9) | 0.043 (6)* | |
H5B | 0.302 (4) | −0.2030 (14) | 0.4887 (8) | 0.034 (5)* | |
H5C | 0.526 (5) | −0.1554 (16) | 0.4525 (8) | 0.040 (6)* | |
C6 | 0.2335 (3) | 0.12921 (10) | 0.47018 (5) | 0.0209 (3) | |
C7 | 0.5913 (3) | 0.06860 (10) | 0.37335 (5) | 0.0195 (3) | |
C8 | 0.8909 (3) | 0.12808 (11) | 0.31097 (5) | 0.0214 (3) | |
H8A | 1.018 (4) | 0.0822 (13) | 0.2966 (7) | 0.023 (4)* | |
H8B | 0.746 (3) | 0.1242 (12) | 0.2898 (6) | 0.016 (4)* | |
C9 | 0.9917 (3) | 0.23248 (10) | 0.31308 (5) | 0.0218 (3) | |
H9 | 1.136 (4) | 0.2340 (14) | 0.3393 (7) | 0.033 (5)* | |
C10 | 0.7894 (3) | 0.30772 (10) | 0.32413 (5) | 0.0227 (3) | |
C11 | 0.6461 (3) | 0.32177 (11) | 0.36923 (6) | 0.0273 (3) | |
H11 | 0.678 (4) | 0.2802 (14) | 0.4013 (7) | 0.032 (5)* | |
C12 | 0.4624 (3) | 0.39449 (12) | 0.36893 (6) | 0.0307 (3) | |
H12 | 0.365 (4) | 0.4056 (14) | 0.4011 (8) | 0.037 (5)* | |
C13 | 0.4225 (3) | 0.45181 (12) | 0.32390 (7) | 0.0307 (3) | |
H13 | 0.289 (4) | 0.5019 (16) | 0.3241 (8) | 0.038 (5)* | |
C14 | 0.5681 (3) | 0.43873 (11) | 0.27881 (6) | 0.0272 (3) | |
H14 | 0.540 (4) | 0.4779 (14) | 0.2461 (8) | 0.033 (5)* | |
C15 | 0.7524 (3) | 0.36682 (10) | 0.27912 (5) | 0.0222 (3) | |
C16 | 0.9326 (3) | 0.33767 (10) | 0.23824 (5) | 0.0218 (3) | |
C17 | 0.9758 (3) | 0.37521 (11) | 0.18767 (5) | 0.0251 (3) | |
H17 | 0.877 (4) | 0.4283 (15) | 0.1741 (7) | 0.033 (5)* | |
C18 | 1.1730 (3) | 0.33647 (11) | 0.15819 (6) | 0.0271 (3) | |
H18 | 1.201 (4) | 0.3628 (13) | 0.1225 (7) | 0.027 (4)* | |
C19 | 1.3197 (3) | 0.26081 (11) | 0.17784 (6) | 0.0270 (3) | |
H19 | 1.452 (4) | 0.2330 (14) | 0.1573 (7) | 0.030 (5)* | |
C20 | 1.2715 (3) | 0.22127 (11) | 0.22789 (6) | 0.0248 (3) | |
H20 | 1.374 (4) | 0.1663 (14) | 0.2398 (7) | 0.029 (5)* | |
C21 | 1.0792 (3) | 0.26106 (10) | 0.25795 (5) | 0.0219 (3) |
U11 | U22 | U33 | U12 | U13 | U23 | |
O1 | 0.0187 (5) | 0.0237 (5) | 0.0284 (5) | 0.0005 (4) | 0.0011 (4) | −0.0042 (4) |
O2 | 0.0264 (6) | 0.0232 (5) | 0.0365 (5) | −0.0060 (5) | 0.0050 (5) | −0.0056 (4) |
O3 | 0.0191 (5) | 0.0341 (5) | 0.0231 (4) | −0.0028 (5) | −0.0025 (4) | 0.0014 (4) |
O4 | 0.0169 (5) | 0.0277 (5) | 0.0210 (4) | −0.0022 (4) | −0.0003 (4) | 0.0047 (4) |
N1 | 0.0162 (5) | 0.0243 (5) | 0.0199 (5) | −0.0010 (5) | −0.0006 (4) | 0.0006 (4) |
C1 | 0.0166 (6) | 0.0209 (6) | 0.0219 (6) | −0.0012 (5) | 0.0009 (5) | −0.0011 (5) |
C2 | 0.0196 (6) | 0.0214 (6) | 0.0254 (6) | −0.0013 (5) | 0.0031 (5) | 0.0008 (5) |
C3 | 0.0373 (10) | 0.0340 (8) | 0.0253 (7) | −0.0043 (7) | −0.0023 (6) | 0.0050 (6) |
C4 | 0.0577 (13) | 0.0424 (10) | 0.0287 (8) | −0.0021 (10) | −0.0003 (8) | 0.0117 (7) |
C5 | 0.0400 (10) | 0.0229 (7) | 0.0334 (7) | 0.0015 (7) | 0.0038 (7) | 0.0012 (6) |
C6 | 0.0197 (7) | 0.0229 (6) | 0.0203 (5) | −0.0006 (6) | −0.0005 (5) | −0.0009 (5) |
C7 | 0.0177 (6) | 0.0186 (6) | 0.0222 (6) | −0.0001 (5) | 0.0011 (5) | −0.0005 (4) |
C8 | 0.0203 (7) | 0.0250 (6) | 0.0189 (5) | −0.0008 (6) | 0.0003 (5) | 0.0040 (5) |
C9 | 0.0197 (6) | 0.0244 (6) | 0.0214 (6) | −0.0024 (5) | −0.0004 (5) | 0.0024 (5) |
C10 | 0.0221 (7) | 0.0228 (6) | 0.0233 (6) | −0.0024 (6) | −0.0008 (5) | −0.0009 (5) |
C11 | 0.0298 (8) | 0.0280 (7) | 0.0239 (6) | −0.0033 (6) | 0.0026 (6) | −0.0008 (5) |
C12 | 0.0306 (8) | 0.0310 (8) | 0.0306 (7) | −0.0015 (7) | 0.0065 (6) | −0.0053 (6) |
C13 | 0.0287 (8) | 0.0268 (7) | 0.0367 (7) | 0.0032 (7) | 0.0011 (6) | −0.0055 (6) |
C14 | 0.0292 (8) | 0.0239 (7) | 0.0287 (7) | 0.0014 (6) | −0.0022 (6) | −0.0001 (5) |
C15 | 0.0217 (7) | 0.0215 (6) | 0.0234 (6) | −0.0035 (6) | −0.0012 (5) | −0.0013 (5) |
C16 | 0.0206 (7) | 0.0215 (6) | 0.0234 (6) | −0.0034 (5) | −0.0004 (5) | −0.0001 (5) |
C17 | 0.0295 (8) | 0.0228 (6) | 0.0230 (6) | −0.0015 (6) | −0.0005 (6) | 0.0018 (5) |
C18 | 0.0322 (9) | 0.0267 (7) | 0.0224 (6) | −0.0064 (6) | 0.0031 (6) | 0.0012 (5) |
C19 | 0.0245 (8) | 0.0290 (7) | 0.0274 (6) | −0.0037 (6) | 0.0040 (6) | −0.0027 (5) |
C20 | 0.0209 (7) | 0.0257 (7) | 0.0277 (6) | −0.0028 (6) | 0.0008 (6) | 0.0007 (5) |
C21 | 0.0192 (7) | 0.0233 (6) | 0.0230 (6) | −0.0039 (6) | −0.0005 (5) | 0.0012 (5) |
O1—C6 | 1.3270 (18) | C8—H8B | 0.942 (17) |
O1—H1H | 0.88 (2) | C9—C10 | 1.518 (2) |
O2—C6 | 1.2102 (18) | C9—C21 | 1.5196 (18) |
O3—C7 | 1.2122 (17) | C9—H9 | 1.01 (2) |
O4—C7 | 1.3471 (17) | C10—C11 | 1.385 (2) |
O4—C8 | 1.4541 (16) | C10—C15 | 1.4092 (19) |
N1—C7 | 1.3675 (17) | C11—C12 | 1.397 (2) |
N1—C1 | 1.4484 (18) | C11—H11 | 1.005 (19) |
N1—H1N | 0.88 (2) | C12—C13 | 1.398 (2) |
C1—C6 | 1.5284 (19) | C12—H12 | 0.98 (2) |
C1—C2 | 1.5462 (19) | C13—C14 | 1.390 (2) |
C1—H1 | 1.015 (19) | C13—H13 | 0.99 (2) |
C2—C5 | 1.525 (2) | C14—C15 | 1.392 (2) |
C2—C3 | 1.531 (2) | C14—H14 | 1.00 (2) |
C2—H2 | 0.975 (19) | C15—C16 | 1.466 (2) |
C3—C4 | 1.526 (2) | C16—C17 | 1.3957 (19) |
C3—H3A | 1.01 (2) | C16—C21 | 1.400 (2) |
C3—H3B | 1.01 (2) | C17—C18 | 1.393 (2) |
C4—H4A | 1.03 (3) | C17—H17 | 0.96 (2) |
C4—H4B | 1.00 (2) | C18—C19 | 1.390 (2) |
C4—H4C | 0.98 (3) | C18—H18 | 0.983 (18) |
C5—H5A | 1.02 (2) | C19—C20 | 1.399 (2) |
C5—H5B | 1.00 (2) | C19—H19 | 0.96 (2) |
C5—H5C | 1.00 (2) | C20—C21 | 1.387 (2) |
C8—C9 | 1.529 (2) | C20—H20 | 0.98 (2) |
C8—H8A | 0.993 (19) | ||
C6—O1—H1H | 108.7 (15) | C9—C8—H8B | 111.2 (10) |
C7—O4—C8 | 116.86 (11) | H8A—C8—H8B | 108.6 (14) |
C7—N1—C1 | 118.91 (12) | C10—C9—C21 | 102.23 (11) |
C7—N1—H1N | 115.3 (12) | C10—C9—C8 | 113.04 (12) |
C1—N1—H1N | 116.5 (12) | C21—C9—C8 | 108.49 (11) |
N1—C1—C6 | 109.97 (11) | C10—C9—H9 | 113.8 (11) |
N1—C1—C2 | 112.46 (11) | C21—C9—H9 | 111.1 (11) |
C6—C1—C2 | 110.73 (11) | C8—C9—H9 | 108.0 (11) |
N1—C1—H1 | 105.0 (11) | C11—C10—C15 | 120.39 (14) |
C6—C1—H1 | 106.5 (10) | C11—C10—C9 | 129.63 (13) |
C2—C1—H1 | 111.9 (11) | C15—C10—C9 | 109.96 (12) |
C5—C2—C3 | 112.62 (14) | C10—C11—C12 | 118.80 (14) |
C5—C2—C1 | 110.13 (12) | C10—C11—H11 | 119.3 (11) |
C3—C2—C1 | 111.90 (12) | C12—C11—H11 | 121.9 (11) |
C5—C2—H2 | 109.7 (11) | C11—C12—C13 | 120.76 (15) |
C3—C2—H2 | 104.8 (10) | C11—C12—H12 | 118.6 (12) |
C1—C2—H2 | 107.5 (11) | C13—C12—H12 | 120.6 (12) |
C4—C3—C2 | 113.36 (15) | C14—C13—C12 | 120.59 (15) |
C4—C3—H3A | 111.4 (12) | C14—C13—H13 | 119.7 (12) |
C2—C3—H3A | 106.6 (13) | C12—C13—H13 | 119.7 (12) |
C4—C3—H3B | 109.2 (12) | C13—C14—C15 | 118.76 (14) |
C2—C3—H3B | 108.9 (12) | C13—C14—H14 | 121.6 (12) |
H3A—C3—H3B | 107.1 (19) | C15—C14—H14 | 119.6 (12) |
C3—C4—H4A | 110.2 (15) | C14—C15—C10 | 120.68 (13) |
C3—C4—H4B | 112.8 (13) | C14—C15—C16 | 130.69 (13) |
H4A—C4—H4B | 109 (2) | C10—C15—C16 | 108.64 (13) |
C3—C4—H4C | 110.1 (16) | C17—C16—C21 | 120.60 (13) |
H4A—C4—H4C | 111 (2) | C17—C16—C15 | 130.71 (14) |
H4B—C4—H4C | 104 (2) | C21—C16—C15 | 108.66 (12) |
C2—C5—H5A | 109.8 (12) | C18—C17—C16 | 118.24 (14) |
C2—C5—H5B | 109.5 (11) | C18—C17—H17 | 120.8 (12) |
H5A—C5—H5B | 106.7 (17) | C16—C17—H17 | 121.0 (12) |
C2—C5—H5C | 111.2 (13) | C19—C18—C17 | 121.20 (14) |
H5A—C5—H5C | 109.4 (17) | C19—C18—H18 | 121.0 (11) |
H5B—C5—H5C | 110.2 (17) | C17—C18—H18 | 117.7 (11) |
O2—C6—O1 | 124.13 (13) | C18—C19—C20 | 120.52 (15) |
O2—C6—C1 | 123.22 (13) | C18—C19—H19 | 121.3 (11) |
O1—C6—C1 | 112.64 (12) | C20—C19—H19 | 118.1 (11) |
O3—C7—O4 | 125.25 (12) | C21—C20—C19 | 118.54 (14) |
O3—C7—N1 | 124.76 (13) | C21—C20—H20 | 123.1 (11) |
O4—C7—N1 | 109.97 (12) | C19—C20—H20 | 118.4 (11) |
O4—C8—C9 | 109.32 (11) | C20—C21—C16 | 120.86 (12) |
O4—C8—H8A | 107.3 (10) | C20—C21—C9 | 128.82 (13) |
C9—C8—H8A | 111.3 (10) | C16—C21—C9 | 110.31 (12) |
O4—C8—H8B | 109.0 (10) | ||
C7—N1—C1—C6 | −88.14 (15) | C12—C13—C14—C15 | 0.7 (2) |
C7—N1—C1—C2 | 147.96 (12) | C13—C14—C15—C10 | 0.6 (2) |
N1—C1—C2—C5 | −62.96 (16) | C13—C14—C15—C16 | −179.33 (15) |
C6—C1—C2—C5 | 173.56 (13) | C11—C10—C15—C14 | −1.4 (2) |
N1—C1—C2—C3 | 63.11 (16) | C9—C10—C15—C14 | 177.23 (13) |
C6—C1—C2—C3 | −60.37 (16) | C11—C10—C15—C16 | 178.54 (13) |
C5—C2—C3—C4 | −65.0 (2) | C9—C10—C15—C16 | −2.87 (16) |
C1—C2—C3—C4 | 170.27 (15) | C14—C15—C16—C17 | 1.9 (3) |
N1—C1—C6—O2 | −6.34 (19) | C10—C15—C16—C17 | −178.03 (15) |
C2—C1—C6—O2 | 118.56 (15) | C14—C15—C16—C21 | 179.97 (15) |
N1—C1—C6—O1 | 174.17 (11) | C10—C15—C16—C21 | 0.08 (16) |
C2—C1—C6—O1 | −60.94 (15) | C21—C16—C17—C18 | −1.9 (2) |
C8—O4—C7—O3 | 0.8 (2) | C15—C16—C17—C18 | 176.00 (14) |
C8—O4—C7—N1 | 179.33 (11) | C16—C17—C18—C19 | 1.5 (2) |
C1—N1—C7—O3 | −17.2 (2) | C17—C18—C19—C20 | 0.3 (2) |
C1—N1—C7—O4 | 164.18 (11) | C18—C19—C20—C21 | −1.8 (2) |
C7—O4—C8—C9 | 121.17 (13) | C19—C20—C21—C16 | 1.4 (2) |
O4—C8—C9—C10 | −73.17 (14) | C19—C20—C21—C9 | −179.33 (14) |
O4—C8—C9—C21 | 174.19 (12) | C17—C16—C21—C20 | 0.5 (2) |
C21—C9—C10—C11 | −177.33 (15) | C15—C16—C21—C20 | −177.88 (13) |
C8—C9—C10—C11 | 66.3 (2) | C17—C16—C21—C9 | −178.93 (13) |
C21—C9—C10—C15 | 4.25 (15) | C15—C16—C21—C9 | 2.74 (16) |
C8—C9—C10—C15 | −112.17 (13) | C10—C9—C21—C20 | 176.47 (14) |
C15—C10—C11—C12 | 0.9 (2) | C8—C9—C21—C20 | −63.88 (19) |
C9—C10—C11—C12 | −177.41 (15) | C10—C9—C21—C16 | −4.22 (15) |
C10—C11—C12—C13 | 0.4 (2) | C8—C9—C21—C16 | 115.44 (13) |
C11—C12—C13—C14 | −1.2 (3) |
D—H···A | D—H | H···A | D···A | D—H···A |
O1—H1H···O2i | 0.88 (2) | 1.77 (2) | 2.6511 (14) | 176 (2) |
N1—H1N···O1ii | 0.88 (2) | 2.18 (2) | 3.0433 (16) | 167.6 (17) |
Symmetry codes: (i) x−1/2, −y+1/2, −z+1; (ii) x+1, y, z. |
Experimental details
Crystal data | |
Chemical formula | C21H23NO4 |
Mr | 353.40 |
Crystal system, space group | Orthorhombic, P212121 |
Temperature (K) | 90 |
a, b, c (Å) | 5.3337 (2), 13.6965 (4), 25.2514 (9) |
V (Å3) | 1844.70 (11) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 0.09 |
Crystal size (mm) | 0.77 × 0.06 × 0.04 |
Data collection | |
Diffractometer | Rigaku AFC-8 with Saturn70 CCD diffractometer |
Absorption correction | – |
No. of measured, independent and observed [I > 2σ(I)] reflections | 19825, 3351, 2993 |
Rint | 0.043 |
(sin θ/λ)max (Å−1) | 0.725 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.034, 0.084, 1.03 |
No. of reflections | 3351 |
No. of parameters | 327 |
H-atom treatment | All H-atom parameters refined |
Δρmax, Δρmin (e Å−3) | 0.23, −0.18 |
Computer programs: CrystalClear (Rigaku/MSC, 2005), HKL-2000 (Otwinowski & Minor, 1997), SIR2004 (Burla et al., 2005), SHELXL97 (Sheldrick, 2008), ORTEP-3 for Windows (Farrugia, 1997).
D—H···A | D—H | H···A | D···A | D—H···A |
O1—H1H···O2i | 0.88 (2) | 1.77 (2) | 2.6511 (14) | 176 (2) |
N1—H1N···O1ii | 0.88 (2) | 2.18 (2) | 3.0433 (16) | 167.6 (17) |
Symmetry codes: (i) x−1/2, −y+1/2, −z+1; (ii) x+1, y, z. |
Acknowledgements
KY thanks the Ministry of Education, Science, Sports, Culture and Technology (MEXT) of Japan for funding this work [Young Scientists (B), 20750022]. TS appreciates support from the World Premier International Research Center Initiative on Materials Nanoarchitronics at NIMS, from MEXT. KD acknowledges the Nanotechnology Support of MEXT.
References
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The fluoren-9-ylmethoxycarbonyl (Fmoc) group is commonly used for protecting the terminal amine of the peptide for the current solid-phase peptide synthesis protocol. This is because cleavage of the Fmoc protecting group is easily achieved by mild basis conditions, e.g., piperidine, but it is very stable under acidic conditions. The crystal structures of N-α-Fmoc-protected-L-alanine monohydrate (Valle et al., 1984), -O-t-butyl-L-serine (Yamada, Hashizume, Shimizu, Ohiki & Yokoyama, 2008) and –L-leucine (Yamada, Hashizume & Shimizu, 2008) have been studied. In this communication, we will report the structure of N-α-Fmoc-L-isoleucine, (I) (Fig. 1).
It is interesting to compare the present structure with that of the analog of the title compound, i.e., N-α-Fmoc-protected-L-leucine, (II). A large fraction of the bond distances and angles, and torsion angles of (I) are consistent with those of (II) except for the following points. First, the orientation of the carboxyl group around the C1—C6 bond is found to be opposite. The torsion angle of O2—C6—C1—N1 for (I) is -6.3 (2)°, while the corresponding angle of (II) is 159.29 (17)°. Second, the angle between the fluorine ring and the NC(=O)O plane is quite different. For example, the torsion angle of C7—O4—C8—C9 and O4—C8—C9—C10 are 121.17 (13) and -73.17 (14)°, respectively, for (I). The corresponding torsion angles of (II), on the other hand, are 93.78 (16) and 60.54 (17)°, respectively. Third, it can be seen that the O3—C7—N1—C1 plane of (I) is slightly pyramided. The N1 atom deviates from the basal plane (C1, C7, H1N) by 0.2086 (12) Å. Moreover, the distances of the N1—C7 and O3—C7 bonds are 1.3675 (17) and 1.2122 (17) Å, respectively, which are approximately 0.026 longer and 0.010 Å shorter than the corresponding bond lengths of (II), respectively. Apparently, the sp2 character of the N1 atom is, to some extent, reduced.
In addition, hydrogen-bond environments are slightly different between the two Fmoc-protected L-amino acids. The crystal of (I) contains two intermolecular hydrogen bonds (Table 1), while that of (II) has three hydrogen bonds. For (I), atom O1 forms two hydrogen bonds with O2 and N1, as shown in Figure 2. The molecules, which related by translation along the a axis are assembled via the N1—H1N···O1 hydrogen bonds to form a one dimensional tape structure. The tapes around the 21 axis, which is parallel to the a axis, are joined together, then the column structure is formed.