The structures of two conformationally restricted 4,5-dihydroxynorvaline analogues with a norbornane skeleton, namely methyl (1S,2S,3R,4R)-2-benzamido-3-(1,2-dihydroxyethyl)bicyclo[2.2.1]heptane-2-carboxylate, C18H23NO5, and methyl (1R,2S,3R,4S)-2-benzamido-3-(1,2-dihydroxyethyl)bicyclo[2.2.1]heptane-2-carboxylate, C18H23NO5, exhibit a conformation in the helical region of the φ,ψ map but their handedness is opposite. In both cases, the torsion angles (χ1,1) giving the relative orientation of the 1,2-dihydroxyethyl group of the amino acid side chain and the benzamide group of the peptide chain indicate that these groups adopt a nearly eclipsed conformation. Both compounds show a complex hydrogen-bonding pattern.
Supporting information
CCDC references: 145545; 145546
Compounds exo-(I) and endo-(I) were prepared according to the
procedure previously described by Buñuel et al. (1996a).
Crystals were obtained by slow evaporation of a methanol solution.
The absolute configuration of compounds exo-(I) and endo-(I) was
deduced from the known stereochemistry of the chiral centre at C17 [for
conformer A of exo-(I) and for endo-(I)] or C35 [for conformer B
of exo-(I)], which was derived from the
(R)—O,O-isopropylideneglyceraldehyde starting material.
H atoms bonded to N or O were located from Fourier syntheses and refined
freely, methyl group H atoms were refined as rigid groups (initial position
from Fourier syntheses, allowed to rotate but not tip) and the remaining H
atoms were treated as riding. All H atoms bonded to C were refined with fixed
individual displacement parameters [Uiso(H) =
1.5Ueq(Cmethyl) or 1.2Ueq(C)]. Molecular geometry
calculations were performed using PARST (Nardelli, 1983).
For both compounds, data collection: XSCANS (Siemens, 1993); cell refinement: XSCANS; data reduction: XSCANS; program(s) used to solve structure: SIR92 (Altomare et al., 1993); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL-Plus (Sheldrick, 1989); software used to prepare material for publication: SHELXL97.
(exoI) methyl
(1
S,2S,3
R,4
R)-2-benzamido-3-(1,2-dihydroxyethyl)bicyclo
[2.2.1]heptane-2-carboxylate
top
Crystal data top
C18H23NO5 | F(000) = 712 |
Mr = 333.37 | Dx = 1.253 Mg m−3 |
Monoclinic, P21 | Mo Kα radiation, λ = 0.71073 Å |
a = 9.323 (5) Å | Cell parameters from 38 reflections |
b = 18.038 (5) Å | θ = 7.2–12.5° |
c = 10.968 (5) Å | µ = 0.09 mm−1 |
β = 106.570 (5)° | T = 293 K |
V = 1767.9 (13) Å3 | Prism, colourless |
Z = 4 | 0.64 × 0.32 × 0.10 mm |
Data collection top
Siemens P4 diffractometer | θmax = 25.0°, θmin = 2.2° |
ω/2θ scans | h = −1→11 |
7359 measured reflections | k = −21→21 |
3213 independent reflections | l = −13→12 |
2274 reflections with I > 2σ(I) | 3 standard reflections every 97 reflections |
Rint = 0.047 | intensity decay: none |
Refinement top
Refinement on F2 | 459 parameters |
Least-squares matrix: full | H atoms treated by a mixture of independent and constrained refinement |
R[F2 > 2σ(F2)] = 0.040 | w = 1/[σ2(Fo2) + (0.0422P)2 + 0.0448P] where P = (Fo2 + 2Fc2)/3 |
wR(F2) = 0.093 | (Δ/σ)max < 0.001 |
S = 1.05 | Δρmax = 0.13 e Å−3 |
3213 reflections | Δρmin = −0.16 e Å−3 |
Crystal data top
C18H23NO5 | V = 1767.9 (13) Å3 |
Mr = 333.37 | Z = 4 |
Monoclinic, P21 | Mo Kα radiation |
a = 9.323 (5) Å | µ = 0.09 mm−1 |
b = 18.038 (5) Å | T = 293 K |
c = 10.968 (5) Å | 0.64 × 0.32 × 0.10 mm |
β = 106.570 (5)° | |
Data collection top
Siemens P4 diffractometer | Rint = 0.047 |
7359 measured reflections | 3 standard reflections every 97 reflections |
3213 independent reflections | intensity decay: none |
2274 reflections with I > 2σ(I) | |
Refinement top
R[F2 > 2σ(F2)] = 0.040 | 459 parameters |
wR(F2) = 0.093 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.05 | Δρmax = 0.13 e Å−3 |
3213 reflections | Δρmin = −0.16 e Å−3 |
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 | x | y | z | Uiso*/Ueq | |
O1 | 0.7287 (4) | −0.1145 (3) | −0.1892 (3) | 0.1053 (12) | |
O2 | 0.7676 (3) | −0.05323 (16) | −0.0069 (3) | 0.0662 (7) | |
O3 | 0.6899 (3) | −0.21963 (14) | 0.0485 (3) | 0.0632 (7) | |
O4 | 0.3258 (3) | −0.02027 (15) | 0.0424 (2) | 0.0522 (6) | |
H4O | 0.317 (4) | 0.007 (2) | 0.098 (4) | 0.058 (13)* | |
O5 | 0.3518 (4) | 0.13752 (18) | 0.0391 (3) | 0.0742 (9) | |
H5O | 0.325 (6) | 0.180 (3) | 0.022 (5) | 0.11 (2)* | |
N1 | 0.5299 (4) | −0.12577 (17) | 0.0338 (3) | 0.0488 (8) | |
H1A | 0.465 (4) | −0.104 (2) | 0.061 (3) | 0.041 (10)* | |
C1 | 0.4350 (5) | −0.1557 (3) | −0.2016 (3) | 0.0664 (11) | |
H1 | 0.4895 | −0.1993 | −0.2179 | 0.080* | |
C2 | 0.5259 (4) | −0.1035 (2) | −0.0953 (3) | 0.0499 (9) | |
C3 | 0.4405 (4) | −0.0275 (2) | −0.1304 (3) | 0.0491 (8) | |
H3 | 0.5052 | 0.0030 | −0.1667 | 0.059* | |
C4 | 0.3063 (5) | −0.0484 (3) | −0.2442 (3) | 0.0677 (12) | |
H4 | 0.2577 | −0.0059 | −0.2950 | 0.081* | |
C5 | 0.1996 (5) | −0.0998 (3) | −0.2059 (4) | 0.0869 (15) | |
H5A | 0.1077 | −0.1057 | −0.2742 | 0.104* | |
H5B | 0.1756 | −0.0816 | −0.1308 | 0.104* | |
C6 | 0.2856 (6) | −0.1720 (3) | −0.1786 (4) | 0.0837 (15) | |
H6B | 0.2990 | −0.1874 | −0.0913 | 0.100* | |
H6A | 0.2332 | −0.2109 | −0.2350 | 0.100* | |
C7 | 0.3821 (5) | −0.1012 (3) | −0.3151 (3) | 0.0745 (13) | |
H7A | 0.4646 | −0.0784 | −0.3387 | 0.089* | |
H7B | 0.3125 | −0.1237 | −0.3889 | 0.089* | |
C8 | 0.6848 (5) | −0.0932 (2) | −0.1033 (4) | 0.0621 (10) | |
C9 | 0.9158 (5) | −0.0336 (3) | −0.0135 (5) | 0.0899 (15) | |
H9A | 0.9656 | −0.0772 | −0.0312 | 0.135* | |
H9B | 0.9723 | −0.0127 | 0.0662 | 0.135* | |
H9C | 0.9078 | 0.0021 | −0.0801 | 0.135* | |
C10 | 0.6090 (4) | −0.18197 (19) | 0.0963 (3) | 0.0473 (9) | |
C11 | 0.6057 (4) | −0.19496 (19) | 0.2299 (3) | 0.0478 (9) | |
C12 | 0.5133 (5) | −0.1578 (3) | 0.2862 (4) | 0.0718 (12) | |
H12 | 0.4445 | −0.1240 | 0.2385 | 0.086* | |
C13 | 0.5199 (7) | −0.1692 (3) | 0.4116 (5) | 0.0909 (16) | |
H13 | 0.4560 | −0.1434 | 0.4479 | 0.109* | |
C14 | 0.6218 (7) | −0.2191 (3) | 0.4832 (4) | 0.0931 (16) | |
H14 | 0.6301 | −0.2253 | 0.5691 | 0.112* | |
C15 | 0.7093 (6) | −0.2587 (3) | 0.4285 (5) | 0.0900 (15) | |
H15 | 0.7750 | −0.2938 | 0.4759 | 0.108* | |
C16 | 0.7017 (5) | −0.2474 (3) | 0.3025 (4) | 0.0730 (12) | |
H16 | 0.7619 | −0.2754 | 0.2656 | 0.088* | |
C17 | 0.4155 (4) | 0.01862 (19) | −0.0218 (3) | 0.0481 (9) | |
H17 | 0.5134 | 0.0274 | 0.0395 | 0.058* | |
C18 | 0.3478 (5) | 0.0933 (2) | −0.0680 (4) | 0.0618 (10) | |
H18A | 0.4042 | 0.1170 | −0.1192 | 0.074* | |
H18B | 0.2452 | 0.0871 | −0.1201 | 0.074* | |
O6 | 0.8972 (3) | −0.03543 (15) | 0.3137 (2) | 0.0661 (7) | |
O7 | 1.0372 (4) | −0.0274 (2) | 0.5124 (3) | 0.1154 (14) | |
O8 | 1.0850 (3) | 0.10855 (18) | 0.3249 (3) | 0.0734 (8) | |
O9 | 0.5477 (3) | 0.13015 (15) | 0.2834 (2) | 0.0584 (7) | |
H9O | 0.461 (6) | 0.130 (4) | 0.218 (5) | 0.14 (2)* | |
O10 | 0.3020 (3) | 0.03100 (19) | 0.2684 (3) | 0.0665 (8) | |
H10O | 0.235 (5) | 0.063 (2) | 0.271 (4) | 0.064 (13)* | |
N2 | 0.8424 (4) | 0.11040 (19) | 0.3119 (3) | 0.0547 (8) | |
H2A | 0.760 (4) | 0.1286 (19) | 0.281 (3) | 0.031 (9)* | |
C19 | 0.9400 (5) | 0.1147 (3) | 0.5519 (4) | 0.0766 (13) | |
H19 | 1.0494 | 0.1129 | 0.5732 | 0.092* | |
C20 | 0.8598 (4) | 0.0702 (2) | 0.4305 (3) | 0.0563 (10) | |
C21 | 0.7045 (4) | 0.0523 (2) | 0.4536 (3) | 0.0585 (10) | |
H21 | 0.7109 | 0.0002 | 0.4797 | 0.070* | |
C22 | 0.7109 (5) | 0.0969 (3) | 0.5760 (4) | 0.0847 (15) | |
H22 | 0.6362 | 0.0826 | 0.6189 | 0.102* | |
C23 | 0.7207 (7) | 0.1790 (4) | 0.5531 (5) | 0.106 (2) | |
H23A | 0.7054 | 0.2072 | 0.6236 | 0.128* | |
H23B | 0.6456 | 0.1937 | 0.4757 | 0.128* | |
C24 | 0.8779 (7) | 0.1920 (3) | 0.5408 (5) | 0.1005 (17) | |
H24A | 0.8746 | 0.2140 | 0.4594 | 0.121* | |
H24B | 0.9361 | 0.2236 | 0.6086 | 0.121* | |
C25 | 0.8777 (5) | 0.0802 (3) | 0.6526 (4) | 0.0878 (16) | |
H25A | 0.9091 | 0.1060 | 0.7335 | 0.105* | |
H25B | 0.8990 | 0.0277 | 0.6645 | 0.105* | |
C26 | 0.9437 (5) | −0.0016 (2) | 0.4249 (4) | 0.0641 (11) | |
C27 | 0.9732 (6) | −0.1038 (3) | 0.3028 (5) | 0.0909 (15) | |
H27A | 1.0759 | −0.0934 | 0.3083 | 0.136* | |
H27B | 0.9255 | −0.1266 | 0.2224 | 0.136* | |
H27C | 0.9688 | −0.1367 | 0.3705 | 0.136* | |
C28 | 0.9550 (4) | 0.1257 (2) | 0.2659 (4) | 0.0559 (10) | |
C29 | 0.9175 (4) | 0.1628 (2) | 0.1393 (3) | 0.0536 (9) | |
C30 | 0.7819 (5) | 0.1536 (2) | 0.0480 (4) | 0.0650 (11) | |
H30 | 0.7104 | 0.1220 | 0.0640 | 0.078* | |
C31 | 0.7509 (5) | 0.1908 (3) | −0.0671 (4) | 0.0749 (12) | |
H31 | 0.6590 | 0.1839 | −0.1275 | 0.090* | |
C32 | 0.8538 (5) | 0.2372 (3) | −0.0927 (4) | 0.0773 (13) | |
H32 | 0.8325 | 0.2625 | −0.1697 | 0.093* | |
C33 | 0.9890 (6) | 0.2461 (3) | −0.0034 (5) | 0.0866 (14) | |
H33 | 1.0600 | 0.2776 | −0.0203 | 0.104* | |
C34 | 1.0218 (5) | 0.2093 (3) | 0.1112 (4) | 0.0750 (13) | |
H34 | 1.1148 | 0.2157 | 0.1703 | 0.090* | |
C35 | 0.5630 (4) | 0.0576 (2) | 0.3413 (3) | 0.0500 (9) | |
H35 | 0.5716 | 0.0213 | 0.2773 | 0.060* | |
C36 | 0.4254 (4) | 0.0393 (2) | 0.3801 (3) | 0.0600 (10) | |
H36A | 0.4407 | −0.0063 | 0.4290 | 0.072* | |
H36B | 0.4047 | 0.0787 | 0.4330 | 0.072* | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
O1 | 0.087 (2) | 0.165 (4) | 0.076 (2) | 0.001 (3) | 0.0422 (18) | −0.029 (2) |
O2 | 0.0511 (15) | 0.0775 (19) | 0.0725 (17) | 0.0027 (15) | 0.0215 (13) | −0.0032 (15) |
O3 | 0.0692 (18) | 0.0518 (15) | 0.0747 (17) | 0.0117 (14) | 0.0303 (15) | −0.0032 (13) |
O4 | 0.0542 (15) | 0.0553 (16) | 0.0504 (15) | 0.0044 (13) | 0.0203 (12) | −0.0010 (13) |
O5 | 0.097 (2) | 0.0529 (17) | 0.0636 (18) | 0.0233 (18) | 0.0075 (16) | 0.0024 (14) |
N1 | 0.0518 (19) | 0.0522 (19) | 0.0437 (17) | 0.0105 (17) | 0.0156 (15) | −0.0010 (14) |
C1 | 0.083 (3) | 0.065 (2) | 0.051 (2) | −0.002 (2) | 0.018 (2) | −0.0139 (19) |
C2 | 0.055 (2) | 0.055 (2) | 0.0403 (18) | 0.0048 (19) | 0.0153 (16) | −0.0014 (17) |
C3 | 0.049 (2) | 0.056 (2) | 0.0428 (17) | 0.0011 (19) | 0.0141 (15) | 0.0078 (16) |
C4 | 0.069 (3) | 0.084 (3) | 0.0403 (19) | 0.003 (3) | −0.0007 (19) | 0.000 (2) |
C5 | 0.068 (3) | 0.121 (4) | 0.064 (3) | −0.022 (3) | 0.006 (2) | −0.014 (3) |
C6 | 0.092 (4) | 0.095 (4) | 0.056 (3) | −0.040 (3) | 0.008 (2) | −0.004 (2) |
C7 | 0.090 (3) | 0.095 (3) | 0.038 (2) | −0.014 (3) | 0.018 (2) | −0.009 (2) |
C8 | 0.063 (3) | 0.074 (3) | 0.053 (2) | 0.011 (2) | 0.023 (2) | 0.000 (2) |
C9 | 0.056 (3) | 0.104 (4) | 0.116 (4) | −0.002 (3) | 0.035 (3) | 0.002 (3) |
C10 | 0.044 (2) | 0.042 (2) | 0.054 (2) | −0.0003 (18) | 0.0102 (17) | −0.0059 (17) |
C11 | 0.049 (2) | 0.0401 (19) | 0.051 (2) | −0.0025 (18) | 0.0094 (17) | 0.0015 (16) |
C12 | 0.093 (3) | 0.063 (2) | 0.065 (3) | 0.015 (3) | 0.031 (2) | 0.016 (2) |
C13 | 0.138 (5) | 0.080 (3) | 0.074 (3) | 0.008 (3) | 0.060 (3) | 0.009 (3) |
C14 | 0.116 (4) | 0.106 (4) | 0.054 (3) | −0.011 (4) | 0.020 (3) | 0.020 (3) |
C15 | 0.085 (3) | 0.101 (4) | 0.075 (3) | 0.015 (3) | 0.008 (3) | 0.030 (3) |
C16 | 0.064 (3) | 0.081 (3) | 0.068 (3) | 0.010 (3) | 0.009 (2) | 0.011 (2) |
C17 | 0.045 (2) | 0.048 (2) | 0.0466 (18) | 0.0064 (18) | 0.0054 (16) | 0.0052 (16) |
C18 | 0.064 (3) | 0.057 (2) | 0.055 (2) | 0.009 (2) | 0.0023 (19) | 0.0078 (19) |
O6 | 0.0616 (16) | 0.0592 (17) | 0.0652 (16) | 0.0082 (15) | −0.0017 (13) | −0.0054 (14) |
O7 | 0.118 (3) | 0.122 (3) | 0.0713 (19) | 0.062 (3) | −0.0285 (19) | −0.004 (2) |
O8 | 0.0373 (15) | 0.102 (2) | 0.0743 (17) | 0.0130 (16) | 0.0048 (13) | −0.0099 (16) |
O9 | 0.0462 (15) | 0.0624 (16) | 0.0583 (15) | 0.0068 (14) | 0.0014 (13) | 0.0070 (13) |
O10 | 0.0434 (15) | 0.093 (2) | 0.0628 (16) | 0.0065 (16) | 0.0150 (13) | −0.0142 (15) |
N2 | 0.0351 (17) | 0.066 (2) | 0.0563 (19) | 0.0074 (17) | 0.0019 (15) | 0.0045 (16) |
C19 | 0.063 (3) | 0.090 (4) | 0.060 (3) | 0.005 (3) | −0.009 (2) | −0.014 (2) |
C20 | 0.056 (2) | 0.059 (2) | 0.0439 (19) | 0.007 (2) | −0.0019 (17) | −0.0005 (18) |
C21 | 0.058 (2) | 0.069 (2) | 0.0433 (19) | 0.005 (2) | 0.0057 (17) | 0.0074 (18) |
C22 | 0.076 (3) | 0.130 (5) | 0.046 (2) | 0.012 (3) | 0.014 (2) | −0.010 (2) |
C23 | 0.101 (4) | 0.122 (5) | 0.078 (3) | 0.042 (4) | −0.004 (3) | −0.041 (3) |
C24 | 0.111 (5) | 0.092 (4) | 0.079 (3) | 0.012 (4) | −0.003 (3) | −0.030 (3) |
C25 | 0.084 (3) | 0.121 (4) | 0.046 (2) | 0.019 (3) | −0.001 (2) | −0.004 (2) |
C26 | 0.057 (2) | 0.074 (3) | 0.051 (2) | 0.015 (2) | −0.0027 (19) | 0.003 (2) |
C27 | 0.094 (4) | 0.060 (3) | 0.104 (4) | 0.012 (3) | 0.005 (3) | −0.015 (3) |
C28 | 0.039 (2) | 0.060 (2) | 0.064 (2) | 0.0054 (19) | 0.0092 (18) | −0.0134 (19) |
C29 | 0.043 (2) | 0.060 (2) | 0.060 (2) | −0.001 (2) | 0.0177 (18) | −0.0108 (18) |
C30 | 0.058 (3) | 0.077 (3) | 0.059 (2) | −0.016 (2) | 0.014 (2) | −0.004 (2) |
C31 | 0.071 (3) | 0.094 (3) | 0.057 (3) | −0.015 (3) | 0.014 (2) | −0.007 (2) |
C32 | 0.081 (3) | 0.090 (3) | 0.067 (3) | −0.006 (3) | 0.032 (3) | 0.005 (2) |
C33 | 0.075 (3) | 0.095 (4) | 0.100 (4) | −0.012 (3) | 0.041 (3) | 0.011 (3) |
C34 | 0.052 (2) | 0.088 (3) | 0.084 (3) | −0.005 (2) | 0.018 (2) | 0.000 (3) |
C35 | 0.046 (2) | 0.055 (2) | 0.0452 (18) | 0.0077 (19) | 0.0071 (15) | 0.0025 (17) |
C36 | 0.049 (2) | 0.079 (3) | 0.052 (2) | 0.009 (2) | 0.0148 (18) | −0.001 (2) |
Geometric parameters (Å, º) top
O1—C8 | 1.192 (5) | O6—C26 | 1.322 (4) |
O2—C8 | 1.330 (5) | O6—C27 | 1.444 (5) |
O2—C9 | 1.449 (5) | O7—C26 | 1.192 (4) |
O3—C10 | 1.237 (4) | O8—C28 | 1.239 (4) |
O4—C17 | 1.422 (4) | O9—C35 | 1.444 (5) |
O4—H4O | 0.81 (4) | O9—H9O | 0.92 (6) |
O5—C18 | 1.412 (5) | O10—C36 | 1.430 (4) |
O5—H5O | 0.81 (6) | O10—H10O | 0.86 (4) |
N1—C10 | 1.324 (4) | N2—C28 | 1.317 (5) |
N1—C2 | 1.463 (4) | N2—C20 | 1.458 (5) |
N1—H1A | 0.85 (3) | N2—H2A | 0.82 (3) |
C1—C6 | 1.514 (6) | C19—C24 | 1.502 (8) |
C1—C2 | 1.549 (5) | C19—C25 | 1.519 (6) |
C1—C7 | 1.552 (6) | C19—C20 | 1.552 (5) |
C1—H1 | 0.9800 | C19—H19 | 0.9800 |
C2—C8 | 1.520 (5) | C20—C26 | 1.524 (6) |
C2—C3 | 1.577 (5) | C20—C21 | 1.573 (5) |
C3—C17 | 1.524 (5) | C21—C35 | 1.530 (5) |
C3—C4 | 1.541 (5) | C21—C22 | 1.551 (6) |
C3—H3 | 0.9800 | C21—H21 | 0.9800 |
C4—C5 | 1.504 (6) | C22—C23 | 1.509 (8) |
C4—C7 | 1.524 (6) | C22—C25 | 1.572 (6) |
C4—H4 | 0.9800 | C22—H22 | 0.9800 |
C5—C6 | 1.514 (7) | C23—C24 | 1.528 (8) |
C5—H5A | 0.9700 | C23—H23A | 0.9700 |
C5—H5B | 0.9700 | C23—H23B | 0.9700 |
C6—H6B | 0.9700 | C24—H24A | 0.9700 |
C6—H6A | 0.9700 | C24—H24B | 0.9700 |
C7—H7A | 0.9700 | C25—H25A | 0.9700 |
C7—H7B | 0.9700 | C25—H25B | 0.9700 |
C9—H9A | 0.9600 | C27—H27A | 0.9600 |
C9—H9B | 0.9600 | C27—H27B | 0.9600 |
C9—H9C | 0.9600 | C27—H27C | 0.9600 |
C10—C11 | 1.492 (5) | C28—C29 | 1.490 (5) |
C11—C12 | 1.371 (6) | C29—C30 | 1.381 (5) |
C11—C16 | 1.386 (5) | C29—C34 | 1.383 (5) |
C12—C13 | 1.374 (6) | C30—C31 | 1.386 (6) |
C12—H12 | 0.9300 | C30—H30 | 0.9300 |
C13—C14 | 1.380 (7) | C31—C32 | 1.361 (6) |
C13—H13 | 0.9300 | C31—H31 | 0.9300 |
C14—C15 | 1.347 (7) | C32—C33 | 1.367 (7) |
C14—H14 | 0.9300 | C32—H32 | 0.9300 |
C15—C16 | 1.379 (6) | C33—C34 | 1.377 (7) |
C15—H15 | 0.9300 | C33—H33 | 0.9300 |
C16—H16 | 0.9300 | C34—H34 | 0.9300 |
C17—C18 | 1.513 (5) | C35—C36 | 1.499 (5) |
C17—H17 | 0.9800 | C35—H35 | 0.9800 |
C18—H18A | 0.9700 | C36—H36A | 0.9700 |
C18—H18B | 0.9700 | C36—H36B | 0.9700 |
| | | |
C8—O2—C9 | 115.9 (3) | C26—O6—C27 | 115.5 (3) |
C17—O4—H4O | 106 (3) | C35—O9—H9O | 107 (5) |
C18—O5—H5O | 114 (4) | C36—O10—H10O | 109 (3) |
C10—N1—C2 | 124.6 (3) | C28—N2—C20 | 123.2 (3) |
C10—N1—H1A | 121 (2) | C28—N2—H2A | 121 (2) |
C2—N1—H1A | 113 (2) | C20—N2—H2A | 115 (2) |
C6—C1—C2 | 109.0 (3) | C24—C19—C25 | 102.7 (4) |
C6—C1—C7 | 99.2 (4) | C24—C19—C20 | 109.3 (3) |
C2—C1—C7 | 101.5 (3) | C25—C19—C20 | 102.8 (4) |
C6—C1—H1 | 115.1 | C24—C19—H19 | 113.6 |
C2—C1—H1 | 115.1 | C25—C19—H19 | 113.6 |
C7—C1—H1 | 115.1 | C20—C19—H19 | 113.6 |
N1—C2—C8 | 109.5 (3) | N2—C20—C26 | 108.3 (3) |
N1—C2—C1 | 114.8 (3) | N2—C20—C19 | 114.4 (3) |
C8—C2—C1 | 111.4 (3) | C26—C20—C19 | 110.3 (3) |
N1—C2—C3 | 110.3 (3) | N2—C20—C21 | 111.9 (3) |
C8—C2—C3 | 108.2 (3) | C26—C20—C21 | 109.8 (3) |
C1—C2—C3 | 102.4 (3) | C19—C20—C21 | 102.0 (3) |
C17—C3—C4 | 119.8 (3) | C35—C21—C22 | 118.4 (4) |
C17—C3—C2 | 117.6 (3) | C35—C21—C20 | 118.7 (3) |
C4—C3—C2 | 102.8 (3) | C22—C21—C20 | 102.9 (3) |
C17—C3—H3 | 105.1 | C35—C21—H21 | 105.1 |
C4—C3—H3 | 105.1 | C22—C21—H21 | 105.1 |
C2—C3—H3 | 105.1 | C20—C21—H21 | 105.1 |
C5—C4—C7 | 101.4 (4) | C23—C22—C21 | 110.7 (4) |
C5—C4—C3 | 111.9 (3) | C23—C22—C25 | 100.3 (5) |
C7—C4—C3 | 100.3 (3) | C21—C22—C25 | 98.7 (4) |
C5—C4—H4 | 113.9 | C23—C22—H22 | 115.0 |
C7—C4—H4 | 113.9 | C21—C22—H22 | 115.0 |
C3—C4—H4 | 113.9 | C25—C22—H22 | 115.0 |
C4—C5—C6 | 103.3 (4) | C22—C23—C24 | 105.7 (5) |
C4—C5—H5A | 111.1 | C22—C23—H23A | 110.6 |
C6—C5—H5A | 111.1 | C24—C23—H23A | 110.6 |
C4—C5—H5B | 111.1 | C22—C23—H23B | 110.6 |
C6—C5—H5B | 111.1 | C24—C23—H23B | 110.6 |
H5A—C5—H5B | 109.1 | H23A—C23—H23B | 108.7 |
C1—C6—C5 | 105.1 (4) | C19—C24—C23 | 101.9 (5) |
C1—C6—H6B | 110.7 | C19—C24—H24A | 111.4 |
C5—C6—H6B | 110.7 | C23—C24—H24A | 111.4 |
C1—C6—H6A | 110.7 | C19—C24—H24B | 111.4 |
C5—C6—H6A | 110.7 | C23—C24—H24B | 111.4 |
H6B—C6—H6A | 108.8 | H24A—C24—H24B | 109.2 |
C4—C7—C1 | 94.2 (3) | C19—C25—C22 | 93.3 (3) |
C4—C7—H7A | 112.9 | C19—C25—H25A | 113.0 |
C1—C7—H7A | 112.9 | C22—C25—H25A | 113.0 |
C4—C7—H7B | 112.9 | C19—C25—H25B | 113.0 |
C1—C7—H7B | 112.9 | C22—C25—H25B | 113.0 |
H7A—C7—H7B | 110.3 | H25A—C25—H25B | 110.4 |
O1—C8—O2 | 123.5 (4) | O7—C26—O6 | 122.3 (4) |
O1—C8—C2 | 124.4 (4) | O7—C26—C20 | 124.5 (4) |
O2—C8—C2 | 112.0 (3) | O6—C26—C20 | 113.1 (3) |
O2—C9—H9A | 109.5 | O6—C27—H27A | 109.5 |
O2—C9—H9B | 109.5 | O6—C27—H27B | 109.5 |
H9A—C9—H9B | 109.5 | H27A—C27—H27B | 109.5 |
O2—C9—H9C | 109.5 | O6—C27—H27C | 109.5 |
H9A—C9—H9C | 109.5 | H27A—C27—H27C | 109.5 |
H9B—C9—H9C | 109.5 | H27B—C27—H27C | 109.5 |
O3—C10—N1 | 121.2 (3) | O8—C28—N2 | 121.1 (4) |
O3—C10—C11 | 121.0 (3) | O8—C28—C29 | 122.2 (4) |
N1—C10—C11 | 117.6 (3) | N2—C28—C29 | 116.7 (3) |
C12—C11—C16 | 117.4 (4) | C30—C29—C34 | 117.9 (4) |
C12—C11—C10 | 123.9 (3) | C30—C29—C28 | 123.0 (4) |
C16—C11—C10 | 118.7 (4) | C34—C29—C28 | 119.1 (4) |
C11—C12—C13 | 121.6 (4) | C29—C30—C31 | 120.8 (4) |
C11—C12—H12 | 119.2 | C29—C30—H30 | 119.6 |
C13—C12—H12 | 119.2 | C31—C30—H30 | 119.6 |
C12—C13—C14 | 119.6 (5) | C32—C31—C30 | 120.6 (4) |
C12—C13—H13 | 120.2 | C32—C31—H31 | 119.7 |
C14—C13—H13 | 120.2 | C30—C31—H31 | 119.7 |
C15—C14—C13 | 119.9 (4) | C31—C32—C33 | 119.0 (4) |
C15—C14—H14 | 120.0 | C31—C32—H32 | 120.5 |
C13—C14—H14 | 120.0 | C33—C32—H32 | 120.5 |
C14—C15—C16 | 120.2 (5) | C32—C33—C34 | 121.1 (5) |
C14—C15—H15 | 119.9 | C32—C33—H33 | 119.5 |
C16—C15—H15 | 119.9 | C34—C33—H33 | 119.5 |
C15—C16—C11 | 121.1 (5) | C33—C34—C29 | 120.6 (4) |
C15—C16—H16 | 119.4 | C33—C34—H34 | 119.7 |
C11—C16—H16 | 119.4 | C29—C34—H34 | 119.7 |
O4—C17—C18 | 110.9 (3) | O9—C35—C36 | 109.8 (3) |
O4—C17—C3 | 111.1 (3) | O9—C35—C21 | 111.4 (3) |
C18—C17—C3 | 111.5 (3) | C36—C35—C21 | 111.6 (3) |
O4—C17—H17 | 107.7 | O9—C35—H35 | 107.9 |
C18—C17—H17 | 107.7 | C36—C35—H35 | 107.9 |
C3—C17—H17 | 107.7 | C21—C35—H35 | 107.9 |
O5—C18—C17 | 108.3 (3) | O10—C36—C35 | 108.9 (3) |
O5—C18—H18A | 110.0 | O10—C36—H36A | 109.9 |
C17—C18—H18A | 110.0 | C35—C36—H36A | 109.9 |
O5—C18—H18B | 110.0 | O10—C36—H36B | 109.9 |
C17—C18—H18B | 110.0 | C35—C36—H36B | 109.9 |
H18A—C18—H18B | 108.4 | H36A—C36—H36B | 108.3 |
| | | |
C10—N1—C2—C8 | −52.3 (5) | C28—N2—C20—C26 | −52.4 (5) |
C10—N1—C2—C1 | 73.7 (4) | C28—N2—C20—C19 | 71.0 (5) |
C10—N1—C2—C3 | −171.3 (3) | C28—N2—C20—C21 | −173.6 (4) |
C6—C1—C2—N1 | 47.4 (5) | C24—C19—C20—N2 | 44.5 (5) |
C7—C1—C2—N1 | 151.5 (3) | C25—C19—C20—N2 | 153.2 (3) |
C6—C1—C2—C8 | 172.5 (4) | C24—C19—C20—C26 | 166.9 (4) |
C7—C1—C2—C8 | −83.4 (4) | C25—C19—C20—C26 | −84.4 (4) |
C6—C1—C2—C3 | −72.0 (4) | C24—C19—C20—C21 | −76.4 (5) |
C7—C1—C2—C3 | 32.0 (4) | C25—C19—C20—C21 | 32.2 (4) |
N1—C2—C3—C17 | 15.8 (4) | N2—C20—C21—C35 | 16.9 (5) |
C8—C2—C3—C17 | −103.9 (3) | C26—C20—C21—C35 | −103.5 (4) |
C1—C2—C3—C17 | 138.4 (3) | C19—C20—C21—C35 | 139.5 (4) |
N1—C2—C3—C4 | −118.1 (3) | N2—C20—C21—C22 | −116.2 (4) |
C8—C2—C3—C4 | 122.2 (3) | C26—C20—C21—C22 | 123.5 (4) |
C1—C2—C3—C4 | 4.5 (3) | C19—C20—C21—C22 | 6.5 (4) |
C17—C3—C4—C5 | −65.9 (5) | C35—C21—C22—C23 | −69.8 (6) |
C2—C3—C4—C5 | 66.7 (4) | C20—C21—C22—C23 | 63.3 (5) |
C17—C3—C4—C7 | −172.7 (3) | C35—C21—C22—C25 | −174.4 (4) |
C2—C3—C4—C7 | −40.1 (4) | C20—C21—C22—C25 | −41.2 (5) |
C7—C4—C5—C6 | 35.3 (4) | C21—C22—C23—C24 | −71.2 (5) |
C3—C4—C5—C6 | −70.8 (4) | C25—C22—C23—C24 | 32.3 (4) |
C2—C1—C6—C5 | 69.9 (4) | C25—C19—C24—C23 | −38.5 (4) |
C7—C1—C6—C5 | −35.7 (4) | C20—C19—C24—C23 | 70.2 (5) |
C4—C5—C6—C1 | 0.8 (4) | C22—C23—C24—C19 | 2.6 (5) |
C5—C4—C7—C1 | −56.1 (4) | C24—C19—C25—C22 | 56.8 (4) |
C3—C4—C7—C1 | 58.9 (4) | C20—C19—C25—C22 | −56.7 (4) |
C6—C1—C7—C4 | 55.5 (4) | C23—C22—C25—C19 | −53.3 (4) |
C2—C1—C7—C4 | −56.2 (4) | C21—C22—C25—C19 | 59.7 (4) |
C9—O2—C8—O1 | 2.5 (6) | C27—O6—C26—O7 | −3.4 (6) |
C9—O2—C8—C2 | −173.5 (4) | C27—O6—C26—C20 | 179.8 (4) |
N1—C2—C8—O1 | 136.9 (4) | N2—C20—C26—O7 | 140.6 (5) |
C1—C2—C8—O1 | 8.9 (6) | C19—C20—C26—O7 | 14.7 (6) |
C3—C2—C8—O1 | −102.9 (5) | C21—C20—C26—O7 | −97.0 (5) |
N1—C2—C8—O2 | −47.1 (4) | N2—C20—C26—O6 | −42.7 (4) |
C1—C2—C8—O2 | −175.1 (3) | C19—C20—C26—O6 | −168.5 (4) |
C3—C2—C8—O2 | 73.1 (4) | C21—C20—C26—O6 | 79.8 (4) |
C2—N1—C10—O3 | 1.6 (5) | C20—N2—C28—O8 | −2.7 (6) |
C2—N1—C10—C11 | 177.3 (3) | C20—N2—C28—C29 | 176.1 (3) |
O3—C10—C11—C12 | −176.6 (4) | O8—C28—C29—C30 | 150.1 (4) |
N1—C10—C11—C12 | 7.7 (5) | N2—C28—C29—C30 | −28.6 (5) |
O3—C10—C11—C16 | 3.6 (5) | O8—C28—C29—C34 | −30.5 (6) |
N1—C10—C11—C16 | −172.1 (3) | N2—C28—C29—C34 | 150.7 (4) |
C16—C11—C12—C13 | 3.0 (7) | C34—C29—C30—C31 | −1.0 (6) |
C10—C11—C12—C13 | −176.7 (4) | C28—C29—C30—C31 | 178.4 (4) |
C11—C12—C13—C14 | 0.1 (8) | C29—C30—C31—C32 | 0.0 (7) |
C12—C13—C14—C15 | −3.1 (8) | C30—C31—C32—C33 | 0.6 (7) |
C13—C14—C15—C16 | 2.7 (8) | C31—C32—C33—C34 | −0.3 (8) |
C14—C15—C16—C11 | 0.6 (8) | C32—C33—C34—C29 | −0.7 (8) |
C12—C11—C16—C15 | −3.4 (6) | C30—C29—C34—C33 | 1.3 (6) |
C10—C11—C16—C15 | 176.3 (4) | C28—C29—C34—C33 | −178.1 (4) |
C4—C3—C17—O4 | 63.9 (4) | C22—C21—C35—O9 | 69.4 (5) |
C2—C3—C17—O4 | −62.0 (4) | C20—C21—C35—O9 | −56.4 (5) |
C4—C3—C17—C18 | −60.3 (5) | C22—C21—C35—C36 | −53.8 (5) |
C2—C3—C17—C18 | 173.8 (3) | C20—C21—C35—C36 | −179.6 (4) |
O4—C17—C18—O5 | 65.6 (4) | O9—C35—C36—O10 | 67.1 (4) |
C3—C17—C18—O5 | −170.0 (3) | C21—C35—C36—O10 | −168.8 (3) |
Hydrogen-bond geometry (Å, º) top
D—H···A | D—H | H···A | D···A | D—H···A |
O4—H4O···O10 | 0.81 (4) | 1.96 (4) | 2.714 (4) | 155 (4) |
O5—H5O···O3i | 0.81 (6) | 1.96 (6) | 2.739 (4) | 161 (5) |
N1—H1A···O4 | 0.85 (3) | 1.97 (4) | 2.712 (4) | 146 (3) |
O9—H9O···O5 | 0.92 (6) | 1.94 (6) | 2.783 (4) | 153 (5) |
O10—H10O···O8ii | 0.86 (4) | 1.86 (4) | 2.673 (4) | 159 (4) |
N2—H2A···O9 | 0.82 (3) | 1.98 (3) | 2.698 (4) | 146 (3) |
O4—H4O···O5 | 0.81 (4) | 2.49 (4) | 2.857 (4) | 109 (3) |
O9—H9O···O10 | 0.92 (6) | 2.48 (6) | 2.874 (4) | 106 (5) |
C5—H5B···O4 | 0.97 | 2.30 | 3.005 (5) | 129 |
C7—H7A···O1 | 0.97 | 2.62 | 3.140 (6) | 114 |
C12—H12···O4 | 0.93 | 2.83 | 3.701 (5) | 157 |
C4—H4···O7iii | 0.98 | 2.52 | 3.121 (5) | 119 |
C5—H5A···O7iii | 0.97 | 2.65 | 3.298 (6) | 125 |
C15—H15···O8iv | 0.93 | 2.82 | 3.711 (6) | 161 |
C23—H23B···O9 | 0.97 | 2.35 | 3.067 (6) | 131 |
C25—H25B···O7 | 0.97 | 2.58 | 3.107 (6) | 114 |
C33—H33···O3v | 0.93 | 2.44 | 3.230 (6) | 143 |
Symmetry codes: (i) −x+1, y+1/2, −z; (ii) x−1, y, z; (iii) x−1, y, z−1; (iv) −x+2, y−1/2, −z+1; (v) −x+2, y+1/2, −z. |
(endoI) methyl
(1
R,2S,3
R,4S)-2-benzamido-3-(1,2-dihydroxyethyl)bicyclo[2.2.1]heptane-2- carboxylate
top
Crystal data top
C18H23NO5 | Dx = 1.298 Mg m−3 |
Mr = 333.37 | Mo Kα radiation, λ = 0.71073 Å |
Orthorhombic, P212121 | Cell parameters from 28 reflections |
a = 7.187 (5) Å | θ = 7.6–12.5° |
b = 11.720 (5) Å | µ = 0.10 mm−1 |
c = 20.258 (5) Å | T = 293 K |
V = 1706.4 (15) Å3 | Prism, colourless |
Z = 4 | 0.40 × 0.36 × 0.30 mm |
F(000) = 712 | |
Data collection top
Siemens P4 diffractometer | θmax = 25.0°, θmin = 2.0° |
ω/2θ scans | h = −8→8 |
3472 measured reflections | k = −13→13 |
1748 independent reflections | l = −24→24 |
1525 reflections with I > 2σ(I) | 3 standard reflections every 97 reflections |
Rint = 0.013 | intensity decay: none |
Refinement top
Refinement on F2 | H atoms treated by a mixture of independent and constrained refinement |
Least-squares matrix: full | w = 1/[σ2(Fo2) + (0.031P)2 + 0.3022P] where P = (Fo2 + 2Fc2)/3 |
R[F2 > 2σ(F2)] = 0.029 | (Δ/σ)max < 0.001 |
wR(F2) = 0.070 | Δρmax = 0.16 e Å−3 |
S = 1.06 | Δρmin = −0.11 e Å−3 |
1748 reflections | Extinction correction: SHELXL97 (Sheldrick, 1997), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4 |
231 parameters | Extinction coefficient: 0.054 (2) |
Crystal data top
C18H23NO5 | V = 1706.4 (15) Å3 |
Mr = 333.37 | Z = 4 |
Orthorhombic, P212121 | Mo Kα radiation |
a = 7.187 (5) Å | µ = 0.10 mm−1 |
b = 11.720 (5) Å | T = 293 K |
c = 20.258 (5) Å | 0.40 × 0.36 × 0.30 mm |
Data collection top
Siemens P4 diffractometer | Rint = 0.013 |
3472 measured reflections | 3 standard reflections every 97 reflections |
1748 independent reflections | intensity decay: none |
1525 reflections with I > 2σ(I) | |
Refinement top
R[F2 > 2σ(F2)] = 0.029 | 231 parameters |
wR(F2) = 0.070 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.06 | Δρmax = 0.16 e Å−3 |
1748 reflections | Δρmin = −0.11 e Å−3 |
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 | x | y | z | Uiso*/Ueq | |
O1 | −0.4223 (2) | 0.79237 (16) | 0.88666 (9) | 0.0566 (5) | |
O2 | −0.2728 (2) | 0.66717 (12) | 0.82224 (8) | 0.0491 (4) | |
O3 | −0.3937 (2) | 0.84340 (16) | 0.73155 (8) | 0.0504 (4) | |
O4 | 0.0100 (3) | 1.08672 (15) | 0.78474 (9) | 0.0553 (5) | |
H4O | 0.000 (5) | 1.143 (3) | 0.7567 (15) | 0.074 (9)* | |
O5 | −0.2572 (3) | 1.25889 (15) | 0.78843 (10) | 0.0526 (5) | |
H5O | −0.359 (4) | 1.282 (3) | 0.7807 (14) | 0.063 (9)* | |
N | −0.0940 (3) | 0.84494 (17) | 0.76384 (9) | 0.0345 (4) | |
H | 0.020 (4) | 0.850 (2) | 0.7516 (12) | 0.048 (7)* | |
C1 | 0.0446 (3) | 0.8040 (2) | 0.87218 (12) | 0.0438 (6) | |
H1 | 0.1071 | 0.7391 | 0.8513 | 0.053* | |
C2 | −0.1312 (3) | 0.84683 (18) | 0.83492 (10) | 0.0345 (5) | |
C3 | −0.1556 (3) | 0.97147 (18) | 0.86306 (10) | 0.0364 (5) | |
H3 | −0.2697 | 0.9731 | 0.8895 | 0.044* | |
C4 | 0.0109 (4) | 0.9823 (2) | 0.91031 (12) | 0.0503 (6) | |
H4 | 0.0472 | 1.0611 | 0.9202 | 0.060* | |
C5 | −0.0270 (5) | 0.9086 (2) | 0.97168 (12) | 0.0618 (8) | |
H5A | −0.1519 | 0.9211 | 0.9884 | 0.074* | |
H5B | 0.0619 | 0.9248 | 1.0065 | 0.074* | |
C6 | −0.0038 (4) | 0.7858 (2) | 0.94560 (12) | 0.0544 (7) | |
H6A | −0.1181 | 0.7426 | 0.9505 | 0.065* | |
H6B | 0.0957 | 0.7464 | 0.9685 | 0.065* | |
C7 | 0.1613 (3) | 0.9121 (2) | 0.87566 (14) | 0.0540 (7) | |
H7A | 0.1932 | 0.9419 | 0.8324 | 0.065* | |
H7B | 0.2726 | 0.9029 | 0.9022 | 0.065* | |
C8 | −0.2964 (3) | 0.76988 (19) | 0.85022 (11) | 0.0396 (5) | |
C9 | −0.4266 (4) | 0.5888 (2) | 0.82789 (15) | 0.0659 (8) | |
H9A | −0.4352 | 0.5619 | 0.8726 | 0.099* | |
H9B | −0.4071 | 0.5253 | 0.7988 | 0.099* | |
H9C | −0.5399 | 0.6270 | 0.8161 | 0.099* | |
C10 | −0.2261 (3) | 0.84975 (19) | 0.71729 (11) | 0.0377 (5) | |
C11 | −0.1621 (3) | 0.86560 (19) | 0.64807 (11) | 0.0400 (5) | |
C12 | −0.0215 (4) | 0.9407 (2) | 0.63307 (12) | 0.0534 (7) | |
H12 | 0.0382 | 0.9805 | 0.6666 | 0.064* | |
C13 | 0.0316 (5) | 0.9570 (2) | 0.56801 (13) | 0.0644 (8) | |
H13 | 0.1257 | 1.0086 | 0.5580 | 0.077* | |
C14 | −0.0534 (5) | 0.8978 (3) | 0.51866 (13) | 0.0671 (8) | |
H14 | −0.0167 | 0.9085 | 0.4751 | 0.081* | |
C15 | −0.1921 (5) | 0.8230 (3) | 0.53323 (14) | 0.0770 (10) | |
H15 | −0.2492 | 0.7820 | 0.4996 | 0.092* | |
C16 | −0.2484 (4) | 0.8077 (3) | 0.59764 (13) | 0.0648 (8) | |
H16 | −0.3455 | 0.7578 | 0.6071 | 0.078* | |
C17 | −0.1692 (3) | 1.06546 (19) | 0.81111 (11) | 0.0387 (5) | |
H17 | −0.2497 | 1.0385 | 0.7753 | 0.046* | |
C18 | −0.2513 (4) | 1.17388 (18) | 0.83864 (13) | 0.0489 (6) | |
H18A | −0.3760 | 1.1592 | 0.8548 | 0.059* | |
H18B | −0.1762 | 1.2006 | 0.8753 | 0.059* | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
O1 | 0.0474 (10) | 0.0585 (11) | 0.0638 (11) | −0.0028 (9) | 0.0193 (9) | 0.0009 (9) |
O2 | 0.0479 (10) | 0.0376 (8) | 0.0618 (10) | −0.0042 (8) | 0.0006 (9) | −0.0017 (8) |
O3 | 0.0325 (8) | 0.0664 (11) | 0.0525 (10) | −0.0016 (9) | −0.0039 (8) | −0.0020 (9) |
O4 | 0.0560 (11) | 0.0452 (10) | 0.0649 (11) | 0.0055 (9) | 0.0220 (10) | 0.0113 (9) |
O5 | 0.0358 (9) | 0.0488 (10) | 0.0733 (12) | 0.0085 (8) | 0.0033 (9) | 0.0182 (9) |
N | 0.0269 (10) | 0.0401 (10) | 0.0364 (10) | 0.0008 (9) | 0.0004 (8) | −0.0024 (8) |
C1 | 0.0375 (12) | 0.0438 (13) | 0.0500 (14) | 0.0104 (11) | −0.0072 (11) | 0.0004 (11) |
C2 | 0.0326 (11) | 0.0369 (11) | 0.0340 (11) | 0.0051 (10) | −0.0008 (10) | −0.0008 (10) |
C3 | 0.0361 (12) | 0.0367 (12) | 0.0364 (12) | 0.0011 (10) | 0.0022 (10) | −0.0008 (9) |
C4 | 0.0571 (16) | 0.0452 (13) | 0.0486 (13) | −0.0019 (13) | −0.0148 (13) | −0.0045 (11) |
C5 | 0.080 (2) | 0.0651 (16) | 0.0406 (13) | 0.0112 (17) | −0.0131 (15) | −0.0023 (13) |
C6 | 0.0636 (16) | 0.0559 (14) | 0.0436 (13) | 0.0099 (15) | −0.0134 (13) | 0.0082 (12) |
C7 | 0.0360 (12) | 0.0653 (16) | 0.0608 (16) | 0.0011 (13) | −0.0153 (13) | 0.0013 (14) |
C8 | 0.0390 (13) | 0.0405 (12) | 0.0392 (12) | 0.0017 (11) | −0.0019 (11) | 0.0053 (10) |
C9 | 0.0648 (18) | 0.0520 (15) | 0.081 (2) | −0.0207 (16) | −0.0128 (16) | 0.0063 (15) |
C10 | 0.0345 (12) | 0.0359 (11) | 0.0427 (13) | −0.0021 (10) | −0.0026 (10) | −0.0020 (10) |
C11 | 0.0415 (12) | 0.0379 (12) | 0.0407 (12) | 0.0020 (11) | −0.0069 (11) | 0.0006 (10) |
C12 | 0.0615 (16) | 0.0525 (14) | 0.0461 (14) | −0.0108 (14) | 0.0016 (13) | −0.0013 (11) |
C13 | 0.075 (2) | 0.0635 (17) | 0.0544 (16) | −0.0129 (17) | 0.0096 (16) | 0.0099 (14) |
C14 | 0.085 (2) | 0.0762 (19) | 0.0399 (15) | 0.0061 (19) | 0.0014 (16) | 0.0081 (14) |
C15 | 0.090 (2) | 0.100 (2) | 0.0408 (15) | −0.020 (2) | −0.0126 (17) | −0.0068 (15) |
C16 | 0.0669 (17) | 0.0782 (19) | 0.0492 (15) | −0.0232 (17) | −0.0074 (15) | −0.0032 (14) |
C17 | 0.0366 (11) | 0.0403 (12) | 0.0392 (12) | 0.0000 (10) | 0.0001 (10) | −0.0013 (10) |
C18 | 0.0487 (14) | 0.0438 (12) | 0.0542 (14) | 0.0059 (12) | 0.0097 (13) | 0.0071 (11) |
Geometric parameters (Å, º) top
O1—C8 | 1.197 (3) | C5—H5B | 0.9700 |
O2—C8 | 1.341 (3) | C6—H6A | 0.9700 |
O2—C9 | 1.442 (3) | C6—H6B | 0.9700 |
O3—C10 | 1.241 (3) | C7—H7A | 0.9700 |
O4—C17 | 1.416 (3) | C7—H7B | 0.9700 |
O4—H4O | 0.87 (3) | C9—H9A | 0.9600 |
O5—C18 | 1.424 (3) | C9—H9B | 0.9600 |
O5—H5O | 0.80 (3) | C9—H9C | 0.9600 |
N—C10 | 1.340 (3) | C10—C11 | 1.488 (3) |
N—C2 | 1.465 (3) | C11—C12 | 1.374 (3) |
N—H | 0.86 (3) | C11—C16 | 1.375 (3) |
C1—C7 | 1.521 (4) | C12—C13 | 1.385 (4) |
C1—C6 | 1.542 (4) | C12—H12 | 0.9300 |
C1—C2 | 1.555 (3) | C13—C14 | 1.361 (4) |
C1—H1 | 0.9800 | C13—H13 | 0.9300 |
C2—C8 | 1.523 (3) | C14—C15 | 1.360 (4) |
C2—C3 | 1.578 (3) | C14—H14 | 0.9300 |
C3—C17 | 1.527 (3) | C15—C16 | 1.378 (4) |
C3—C4 | 1.538 (3) | C15—H15 | 0.9300 |
C3—H3 | 0.9800 | C16—H16 | 0.9300 |
C4—C7 | 1.529 (4) | C17—C18 | 1.508 (3) |
C4—C5 | 1.538 (4) | C17—H17 | 0.9800 |
C4—H4 | 0.9800 | C18—H18A | 0.9700 |
C5—C6 | 1.542 (4) | C18—H18B | 0.9700 |
C5—H5A | 0.9700 | | |
| | | |
C8—O2—C9 | 116.2 (2) | C1—C7—H7B | 112.8 |
C17—O4—H4O | 108 (2) | C4—C7—H7B | 112.8 |
C18—O5—H5O | 114 (2) | H7A—C7—H7B | 110.3 |
C10—N—C2 | 124.19 (19) | O1—C8—O2 | 123.6 (2) |
C10—N—H | 118.1 (17) | O1—C8—C2 | 125.8 (2) |
C2—N—H | 117.2 (17) | O2—C8—C2 | 110.29 (19) |
C7—C1—C6 | 101.2 (2) | O2—C9—H9A | 109.5 |
C7—C1—C2 | 101.65 (18) | O2—C9—H9B | 109.5 |
C6—C1—C2 | 109.2 (2) | H9A—C9—H9B | 109.5 |
C7—C1—H1 | 114.4 | O2—C9—H9C | 109.5 |
C6—C1—H1 | 114.4 | H9A—C9—H9C | 109.5 |
C2—C1—H1 | 114.4 | H9B—C9—H9C | 109.5 |
N—C2—C8 | 109.48 (17) | O3—C10—N | 121.5 (2) |
N—C2—C1 | 108.91 (18) | O3—C10—C11 | 121.8 (2) |
C8—C2—C1 | 110.10 (17) | N—C10—C11 | 116.71 (19) |
N—C2—C3 | 112.92 (18) | C12—C11—C16 | 118.9 (2) |
C8—C2—C3 | 112.82 (18) | C12—C11—C10 | 121.1 (2) |
C1—C2—C3 | 102.34 (18) | C16—C11—C10 | 120.0 (2) |
C17—C3—C4 | 114.78 (19) | C11—C12—C13 | 120.1 (2) |
C17—C3—C2 | 115.21 (18) | C11—C12—H12 | 120.0 |
C4—C3—C2 | 102.40 (17) | C13—C12—H12 | 120.0 |
C17—C3—H3 | 108.0 | C14—C13—C12 | 120.3 (3) |
C4—C3—H3 | 108.0 | C14—C13—H13 | 119.9 |
C2—C3—H3 | 108.0 | C12—C13—H13 | 119.9 |
C7—C4—C3 | 102.71 (18) | C15—C14—C13 | 119.9 (3) |
C7—C4—C5 | 101.2 (2) | C15—C14—H14 | 120.1 |
C3—C4—C5 | 108.6 (2) | C13—C14—H14 | 120.1 |
C7—C4—H4 | 114.3 | C14—C15—C16 | 120.3 (3) |
C3—C4—H4 | 114.3 | C14—C15—H15 | 119.8 |
C5—C4—H4 | 114.3 | C16—C15—H15 | 119.8 |
C4—C5—C6 | 103.2 (2) | C11—C16—C15 | 120.5 (3) |
C4—C5—H5A | 111.1 | C11—C16—H16 | 119.8 |
C6—C5—H5A | 111.1 | C15—C16—H16 | 119.8 |
C4—C5—H5B | 111.1 | O4—C17—C18 | 110.30 (19) |
C6—C5—H5B | 111.1 | O4—C17—C3 | 109.21 (18) |
H5A—C5—H5B | 109.1 | C18—C17—C3 | 112.21 (19) |
C5—C6—C1 | 103.1 (2) | O4—C17—H17 | 108.3 |
C5—C6—H6A | 111.2 | C18—C17—H17 | 108.3 |
C1—C6—H6A | 111.2 | C3—C17—H17 | 108.3 |
C5—C6—H6B | 111.2 | O5—C18—C17 | 109.7 (2) |
C1—C6—H6B | 111.2 | O5—C18—H18A | 109.7 |
H6A—C6—H6B | 109.1 | C17—C18—H18A | 109.7 |
C1—C7—C4 | 94.5 (2) | O5—C18—H18B | 109.7 |
C1—C7—H7A | 112.8 | C17—C18—H18B | 109.7 |
C4—C7—H7A | 112.8 | H18A—C18—H18B | 108.2 |
| | | |
C10—N—C2—C8 | 42.8 (3) | C9—O2—C8—O1 | 11.4 (3) |
C10—N—C2—C1 | 163.2 (2) | C9—O2—C8—C2 | −174.77 (19) |
C10—N—C2—C3 | −83.8 (3) | N—C2—C8—O1 | −136.3 (2) |
C7—C1—C2—N | 83.3 (2) | C1—C2—C8—O1 | 104.0 (3) |
C6—C1—C2—N | −170.3 (2) | C3—C2—C8—O1 | −9.6 (3) |
C7—C1—C2—C8 | −156.65 (19) | N—C2—C8—O2 | 50.1 (2) |
C6—C1—C2—C8 | −50.2 (2) | C1—C2—C8—O2 | −69.6 (2) |
C7—C1—C2—C3 | −36.5 (2) | C3—C2—C8—O2 | 176.72 (18) |
C6—C1—C2—C3 | 70.0 (2) | C2—N—C10—O3 | −8.2 (4) |
N—C2—C3—C17 | 9.8 (3) | C2—N—C10—C11 | 170.5 (2) |
C8—C2—C3—C17 | −115.0 (2) | O3—C10—C11—C12 | 137.0 (3) |
C1—C2—C3—C17 | 126.7 (2) | N—C10—C11—C12 | −41.7 (3) |
N—C2—C3—C4 | −115.51 (19) | O3—C10—C11—C16 | −40.7 (4) |
C8—C2—C3—C4 | 119.7 (2) | N—C10—C11—C16 | 140.6 (2) |
C1—C2—C3—C4 | 1.4 (2) | C16—C11—C12—C13 | −0.1 (4) |
C17—C3—C4—C7 | −91.6 (2) | C10—C11—C12—C13 | −177.8 (3) |
C2—C3—C4—C7 | 34.0 (2) | C11—C12—C13—C14 | −0.9 (5) |
C17—C3—C4—C5 | 161.8 (2) | C12—C13—C14—C15 | 0.6 (5) |
C2—C3—C4—C5 | −72.6 (2) | C13—C14—C15—C16 | 0.7 (5) |
C7—C4—C5—C6 | −35.3 (3) | C12—C11—C16—C15 | 1.3 (4) |
C3—C4—C5—C6 | 72.4 (3) | C10—C11—C16—C15 | 179.0 (3) |
C4—C5—C6—C1 | 0.0 (3) | C14—C15—C16—C11 | −1.6 (5) |
C7—C1—C6—C5 | 35.5 (3) | C4—C3—C17—O4 | 43.2 (3) |
C2—C1—C6—C5 | −71.2 (3) | C2—C3—C17—O4 | −75.4 (2) |
C6—C1—C7—C4 | −56.2 (2) | C4—C3—C17—C18 | −79.5 (3) |
C2—C1—C7—C4 | 56.3 (2) | C2—C3—C17—C18 | 161.9 (2) |
C3—C4—C7—C1 | −56.0 (2) | O4—C17—C18—O5 | 56.9 (3) |
C5—C4—C7—C1 | 56.2 (2) | C3—C17—C18—O5 | 178.93 (19) |
Hydrogen-bond geometry (Å, º) top
D—H···A | D—H | H···A | D···A | D—H···A |
O4—H4O···Ni | 0.87 (3) | 2.50 (3) | 3.239 (3) | 143 (3) |
O4—H4O···O2i | 0.87 (3) | 2.55 (3) | 3.026 (2) | 116 (3) |
O5—H5O···O3ii | 0.80 (3) | 1.93 (3) | 2.728 (3) | 175 (3) |
N—H···O5iii | 0.86 (3) | 2.17 (3) | 2.917 (3) | 146 (2) |
O4—H4O···O5 | 0.87 (3) | 2.39 (3) | 2.787 (3) | 109 (2) |
C3—H3···O1 | 0.98 | 2.39 | 2.882 (3) | 111 |
C7—H7A···O4 | 0.97 | 2.36 | 2.960 (3) | 120 |
C12—H12···O4 | 0.93 | 2.70 | 3.524 (3) | 148 |
C12—H12···O2i | 0.93 | 2.77 | 3.513 (3) | 138 |
C7—H7B···O1iv | 0.97 | 2.57 | 3.313 (4) | 134 |
C9—H9B···O3v | 0.96 | 2.64 | 3.375 (3) | 134 |
Symmetry codes: (i) −x, y+1/2, −z+3/2; (ii) −x−1, y+1/2, −z+3/2; (iii) −x, y−1/2, −z+3/2; (iv) x+1, y, z; (v) −x−1, y−1/2, −z+3/2. |
Experimental details
| (exoI) | (endoI) |
Crystal data |
Chemical formula | C18H23NO5 | C18H23NO5 |
Mr | 333.37 | 333.37 |
Crystal system, space group | Monoclinic, P21 | Orthorhombic, P212121 |
Temperature (K) | 293 | 293 |
a, b, c (Å) | 9.323 (5), 18.038 (5), 10.968 (5) | 7.187 (5), 11.720 (5), 20.258 (5) |
α, β, γ (°) | 90, 106.570 (5), 90 | 90, 90, 90 |
V (Å3) | 1767.9 (13) | 1706.4 (15) |
Z | 4 | 4 |
Radiation type | Mo Kα | Mo Kα |
µ (mm−1) | 0.09 | 0.10 |
Crystal size (mm) | 0.64 × 0.32 × 0.10 | 0.40 × 0.36 × 0.30 |
|
Data collection |
Diffractometer | Siemens P4 diffractometer | Siemens P4 diffractometer |
Absorption correction | – | – |
No. of measured, independent and observed [I > 2σ(I)] reflections | 7359, 3213, 2274 | 3472, 1748, 1525 |
Rint | 0.047 | 0.013 |
(sin θ/λ)max (Å−1) | 0.595 | 0.595 |
|
Refinement |
R[F2 > 2σ(F2)], wR(F2), S | 0.040, 0.093, 1.05 | 0.029, 0.070, 1.06 |
No. of reflections | 3213 | 1748 |
No. of parameters | 459 | 231 |
No. of restraints | ? | ? |
H-atom treatment | H atoms treated by a mixture of independent and constrained refinement | H atoms treated by a mixture of independent and constrained refinement |
Δρmax, Δρmin (e Å−3) | 0.13, −0.16 | 0.16, −0.11 |
Selected geometric parameters (Å, º) for (exoI) topO1—C8 | 1.192 (5) | C2—C3 | 1.577 (5) |
O4—C17 | 1.422 (4) | C3—C17 | 1.524 (5) |
O5—C18 | 1.412 (5) | C3—C4 | 1.541 (5) |
N1—C2 | 1.463 (4) | C4—C5 | 1.504 (6) |
C1—C6 | 1.514 (6) | C4—C7 | 1.524 (6) |
C1—C2 | 1.549 (5) | C5—C6 | 1.514 (7) |
C1—C7 | 1.552 (6) | C17—C18 | 1.513 (5) |
C2—C8 | 1.520 (5) | | |
| | | |
C6—C1—C2 | 109.0 (3) | C5—C4—C3 | 111.9 (3) |
C6—C1—C7 | 99.2 (4) | C7—C4—C3 | 100.3 (3) |
C2—C1—C7 | 101.5 (3) | C4—C5—C6 | 103.3 (4) |
N1—C2—C1 | 114.8 (3) | C1—C6—C5 | 105.1 (4) |
C8—C2—C1 | 111.4 (3) | O1—C8—C2 | 124.4 (4) |
N1—C2—C3 | 110.3 (3) | O2—C8—C2 | 112.0 (3) |
C8—C2—C3 | 108.2 (3) | N1—C10—C11 | 117.6 (3) |
C1—C2—C3 | 102.4 (3) | O4—C17—C18 | 110.9 (3) |
C17—C3—C4 | 119.8 (3) | O4—C17—C3 | 111.1 (3) |
C17—C3—C2 | 117.6 (3) | C18—C17—C3 | 111.5 (3) |
C4—C3—C2 | 102.8 (3) | O5—C18—C17 | 108.3 (3) |
C5—C4—C7 | 101.4 (4) | | |
Hydrogen-bond geometry (Å, º) for (exoI) top
D—H···A | D—H | H···A | D···A | D—H···A |
O4—H4O···O10 | 0.81 (4) | 1.96 (4) | 2.714 (4) | 155 (4) |
O5—H5O···O3i | 0.81 (6) | 1.96 (6) | 2.739 (4) | 161 (5) |
N1—H1A···O4 | 0.85 (3) | 1.97 (4) | 2.712 (4) | 146 (3) |
O9—H9O···O5 | 0.92 (6) | 1.94 (6) | 2.783 (4) | 153 (5) |
O10—H10O···O8ii | 0.86 (4) | 1.86 (4) | 2.673 (4) | 159 (4) |
N2—H2A···O9 | 0.82 (3) | 1.98 (3) | 2.698 (4) | 146 (3) |
O4—H4O···O5 | 0.81 (4) | 2.49 (4) | 2.857 (4) | 109 (3) |
O9—H9O···O10 | 0.92 (6) | 2.48 (6) | 2.874 (4) | 106 (5) |
C5—H5B···O4 | 0.97 | 2.30 | 3.005 (5) | 129 |
C23—H23B···O9 | 0.97 | 2.35 | 3.067 (6) | 131 |
C33—H33···O3iii | 0.93 | 2.44 | 3.230 (6) | 143 |
Symmetry codes: (i) −x+1, y+1/2, −z; (ii) x−1, y, z; (iii) −x+2, y+1/2, −z. |
Selected geometric parameters (Å, º) for (endoI) topO1—C8 | 1.197 (3) | C2—C3 | 1.578 (3) |
O4—C17 | 1.416 (3) | C3—C17 | 1.527 (3) |
O5—C18 | 1.424 (3) | C3—C4 | 1.538 (3) |
N—C2 | 1.465 (3) | C4—C7 | 1.529 (4) |
C1—C7 | 1.521 (4) | C4—C5 | 1.538 (4) |
C1—C6 | 1.542 (4) | C5—C6 | 1.542 (4) |
C1—C2 | 1.555 (3) | C17—C18 | 1.508 (3) |
C2—C8 | 1.523 (3) | | |
| | | |
C7—C1—C6 | 101.2 (2) | C7—C4—C5 | 101.2 (2) |
C7—C1—C2 | 101.65 (18) | C3—C4—C5 | 108.6 (2) |
C6—C1—C2 | 109.2 (2) | C4—C5—C6 | 103.2 (2) |
N—C2—C1 | 108.91 (18) | C5—C6—C1 | 103.1 (2) |
C8—C2—C1 | 110.10 (17) | O1—C8—C2 | 125.8 (2) |
N—C2—C3 | 112.92 (18) | O2—C8—C2 | 110.29 (19) |
C8—C2—C3 | 112.82 (18) | N—C10—C11 | 116.71 (19) |
C1—C2—C3 | 102.34 (18) | O4—C17—C18 | 110.30 (19) |
C17—C3—C4 | 114.78 (19) | O4—C17—C3 | 109.21 (18) |
C17—C3—C2 | 115.21 (18) | C18—C17—C3 | 112.21 (19) |
C4—C3—C2 | 102.40 (17) | O5—C18—C17 | 109.7 (2) |
C7—C4—C3 | 102.71 (18) | | |
Hydrogen-bond geometry (Å, º) for (endoI) top
D—H···A | D—H | H···A | D···A | D—H···A |
O4—H4O···Ni | 0.87 (3) | 2.50 (3) | 3.239 (3) | 143 (3) |
O4—H4O···O2i | 0.87 (3) | 2.55 (3) | 3.026 (2) | 116 (3) |
O5—H5O···O3ii | 0.80 (3) | 1.93 (3) | 2.728 (3) | 175 (3) |
N—H···O5iii | 0.86 (3) | 2.17 (3) | 2.917 (3) | 146 (2) |
O4—H4O···O5 | 0.87 (3) | 2.39 (3) | 2.787 (3) | 109 (2) |
C3—H3···O1 | 0.98 | 2.39 | 2.882 (3) | 111 |
C7—H7A···O4 | 0.97 | 2.36 | 2.960 (3) | 120 |
C7—H7B···O1iv | 0.97 | 2.57 | 3.313 (4) | 134 |
Symmetry codes: (i) −x, y+1/2, −z+3/2; (ii) −x−1, y+1/2, −z+3/2; (iii) −x, y−1/2, −z+3/2; (iv) x+1, y, z. |
Amino acids containing one or more hydroxy groups form an important class of naturally occurring compounds (Hunt, 1985). Such compounds, whether of natural or synthetic origin, are useful precursors in the synthesis of β-lactams (Miller, 1986). An important example is (2S,4S)-4,5-dihydroxynorvaline (Liao & Zhou, 1998; Girard et al., 1998), which is a key intermediate in the synthesis of antibiotic clavalanine.
For some years, we have been focusing our attention on those amino acids that possess specific conformational and topographical modifications on their side-chain and, in particular, cyclization of the side-chain atoms with the main-chain atoms. This structural modification can result in significant changes in potency, receptor selectivity and biostability when incorporated into bioactive compounds. Recently, we reported our findings on the asymmetric Diels-Alder reaction between (Z)-2-phenyl-4-[(S)-2,2-dimethyl- 1,3-dioxolan-4-ylmethylene]-5-(4H)-oxazolone and cyclopentadiene. The corresponding exo/endo adducts were isolated in enantiomerically pure form and transformed into two new conformationally constrained 4,5-dihydroxynorvaline analogues with a norbornane skeleton (Buñuel et al., 1996a), methyl (1S,2S,3R,4R)-2-benzamido-3-(1,2-dihydroxyethyl)bicyclo [2.2.1]heptane-2-carboxylate, exo-(I), and methyl (1R,2S,3R,4S)-2-benzamido-3-(1,2-dihydroxyethyl)bicyclo[2.2.1]heptane-2- carboxylate, endo-(I). We describe here the crystal and molecular structures of these two new diastereomeric amino acids. \scheme
Compound exo-(I) crystallizes with two molecules (A and B) in the asymmetric unit (Fig. 1). The numbering of the atoms runs from 1 to 18 for the first molecule and from 19 to 36 for the second. These two independent molecules differ slightly in their conformation. The main difference between them is the orientation of the phenyl group, with N1—C10—C11—C12 and O3—C10—C11—C16 torsion angles of 7.7 (5) and 3.6 (5)° for molecule A and N2—C28—C29—C30 and O8—C28—C29—C34 torsion angles of -28.6 (5) and -30.5 (6)° for molecule B. The configuration at the chiral atoms C1, C2, C3, C4 and C17 for the first conformer and at chiral atoms C19, C20, C21, C22 and C35 for the second are S, S, R, R and S, respectively. The bond lengths and angles show small variations from reported values for other norbornane amino acid derivatives (Apgar & Ludwig, 1972; Glass et al., 1990; Buñuel et al., 1996b; Buñuel et al., 1997). The C4—C7—C1 and C19—C25—C22 angles of 94.2 (3) and 93.3 (3)°, respectively, are significantly contracted with respect to the regular tetrahedral value, while the endocyclic angles of the five-membered norbornane rings are in the range 98.7 (4)–105.7 (5)°. The values for the conformationally sensitive N—Cα—C' (τ) bond angles [N1—C2—C8 = 109.5 (3)° and N2—C20—C26 = 108.3 (3)°], which are external to the cyclic system, are very close to the tetrahedral value, as would be expected for the Cα,α-dialkylated glycines that form regular helices (Benedetti et al., 1997).
In the bicyclo[2.2.1]heptane (norbornane) unit of each independent molecule, the two five-membered rings are in envelope conformations, while the six-membered ring adopts an approximate boat conformation. The slightly distorted boat conformation of the norbornane six-membered rings, C1—C6 and C19—C24, is evidenced by the puckering parameters (Cremer & Pople, 1975): q2 = 0.919 (4) Å, q3 = 0.022 (4) Å, ϕ2 = 2.7 (3)°, θ2 = 88,6(2)° and ΘT = 0.919 (4) Å, and q2 = 0.928 (5) Å, q3 = 0.026 (5) Å, ϕ2 = 4.2 (3)°, θ2 = 88.4 (3)° and ΘT = 0.929 (5) Å, respectively. In both independent molecules, the substitution of the norbornane ring produces a twist of type S-(+,+) (Altona & Sundaralingam, 1970) about the C1···C4 or C19···C22 vectors. The twisting can be seen from the C1—C2—C3—C4 and C4—C5—C6—C1 torsion angles of 4.5 (3) and 0.8 (4)°, respectively, for molecule A, and from the C19—C20—C21—C22 and C22—C23—C24—C19 torsion angles of 6.5 (4) and 2.6 (5)°, respectively, for molecule B.
In compound exo-(I), the amino acid residue adopts a folded conformation. The values of the backbone torsion angles ϕ [C10—N1—C2—C8 = -52.3 (5)° for molecule A and C28—N2—C20—C26 = -52.4 (5)° for molecule B] and ψ [N1—C2—C8—O2 = -47.1 (4)° for molecule A and N2—C20—C26—O6 = -42.7 (4)° for molecule B] fall in the A region of the conformational map (Zimmerman et al., 1977). These values differ by less than 20° from those pertaining to the ideal 310-helix (60, 30°) or α-helix (55, 45°). The torsion angles ω [C11—C10—N1—C2 = 177.3 (3)° and C29—C28—N2—C20 = 176.1 (3)°] indicate that the amide linkage adopts the usual trans conformation in both conformers. The spatial arrangement of the 1,2-dihydroxyethyl group of the amino acid side-chain with respect to the peptide chain is defined by the torsion angles χ1,1 [N1—C2—C3—C17 = 15.8 (4)° for molecule A and N2—C20—C21—C35 = 16.9 (5)° for molecule B]. These values indicate that the benzamide and 1,2-dihydroxyethyl groups are in a nearly eclipsed conformation. In addition, both groups are involved in an N—H···O intramolecular hydrogen bond with an N1···O4 distance of 2.712 (4) Å for the first independent molecule and an N2···O9 distance of 2.698 (4) Å for the second. Another short intramolecular contact is observed between the two hydroxy groups [O4···O5 2.857 (4) and O9···O10 2.874 (4) Å].
In the crystals of compound exo-(I), the two independent molecules of the asymmetric unit form dimers in which two hydrogen bonds are observed between the O4—H4O donor of molecule A and the O10 acceptor of molecule B, with a distance of 2.714 (4) Å, and between the O9—H9O donor of molecule B and the O5 acceptor of molecule A, with a distance of 2.783 (4) Å. Moreover, the crystal structure is stabilized by two additional O—H···O intermolecular hydrogen bonds, involving the terminal hydroxy group of each independent molecule and the benzamide group of a symmetry-related molecule of the same type (A or B) [O5···O3 2.739 (4) Å and O10···O8 2.673 (4) Å]. Both hydroxy groups function as hydrogen-bond donors, whereby the molecules are linked into sheets parallel to the z axis (Fig. 2). Some short intra- and intermolecular C—H···O contacts (Table 2) are also found, which can be described as weak hydrogen bonds (Steiner, 1997; Desiraju, 1996).
Diastereoisomer endo-(I) crystallizes with one molecule in the asymmetry unit (Fig. 3). The stereochemistry at the chiral C1, C2, C3, C4 and C17 atoms is R, S, R, S and S, respectively. Comparison of the bond distances and angles in compound endo-(I) with those determined for other norbornane amino acids, and in particular with the compound exo-(I), reveals no strikingly unusual features and these parameters lie within the expected ranges. The C4—C7—C1 angle is 94.5 (2)° and the endocyclic angles of the five-membered norbornane rings vary from 101.2 (2) to 103.2 (2)°, which are all substantially less than the regular tetrahedral value of 109.5°. The critical intra-ring bond angle τ [N—C2—C8 = 109.48 (17)°] is comparable with that in compound exo-(I).
The two five-membered norbornane rings of compound endo-(I) are in envelope conformations, while the six-membered norbornane ring is in an almost perfect boat conformation [puckering parameters are q2 = 0.958 (9) Å, q3 = 0.051 (3) Å, query Chester PLATON gives 0.005 (3) ϕ2 = 179.51 (17)°, θ2 = 89.69 (15)° and ΘT = 0.958 (9) Å]. The norbornane system shows a weak distortion from C2ν symmetry, although it is less important than in exo-(I). The twisting can be seen from the C1—C2—C3—C4 and C4—C5—C6—C1 torsion angles of 1.4 (2) and 0.0 (3)°, respectively.
The amino acid residue in compound endo-(I) exhibits a conformation in the helical region of the ϕ,ψ map, but it has opposite handedness to that shown by compound exo-(I): the values of the backbone torsion angles ϕ [C10—N—C2—C8 = 42.8 (3)°] and ψ [N—C2—C8—O2 = 50.1 (2)°] fall in the A* region of the conformational map (Zimmerman et al., 1977). The torsion angle ω (C11—C10—N—C2) differs by less than 10° from 180°, the ideal value of the trans planar amide unit. In compound endo-(I), the torsion angle χ1,1 [N—C2—C3—C17 = 9.8 (3)°] also shows that the 1,2-dihydroxyethyl and benzamide groups are in a nearly eclipsed conformation. However, in contrast with exo-(I), no intramolecular hydrogen bond is observed between these two groups, whereas the short intramolecular contact involving both hydroxy groups observed in compound exo-(I) is also present in compound endo-(I) [O4···O5 2.787 (3) Å].
Apart from the spatial arrangement of the methyl ester and the benzamido and 1,2-dihydroxyethyl groups relative to the norbornane ring, the main difference between the 4,5-dihydroxynorvaline analogues described here, i.e. endo-(I) and exo-(I), involves the intermolecular hydrogen-bond pattern. In the crystals of endo-(I) three intermolecular hydrogen bonds are seen: one weak O(hydroxy)-H···O/N(amide/methyl ester) three-centre hydrogen bond [O4···N 3.239 (3) Å and O4···O2 3.026 (2) Å], one O(hydroxy)-H···O=C(amide) two-centre hydrogen bond [O5···O3 2.728 (3) Å] and one N(amide)-H···O(hydroxy) two-centre hydrogen bond [N···O5 2.917 (3) Å]. Both OH and NH groups function as hydrogen-bond donors, whereby the molecules are linked into sheets parallel to the z axis (Fig. 4). As in the diastereoisomer exo-(I), some possible borderline cases of C—H···O hydrogen bonds are also present in endo-(I) (Table 4).