organic compounds
1-(1-Carboxymethyl-1,4-anhydro-2,3-O-isopropylidene-α-D-erythrofuranosyl)thymine
aDepartment of Organic Chemistry, Chemistry Research Laboratory, University of Oxford, Mansfield Road, Oxford OX1 3TA, England, bIdenix Pharmaceuticals, Inc., 60 Hampshire Street, Cambridge, MA 02139, USA, and cDepartment of Chemical Crystallography, Chemistry Research Laboratory, University of Oxford, Mansfield Road, Oxford OX1 3TA, England
*Correspondence e-mail: sarah.jenkinson@chem.ox.ac.uk
X-Ray crystallography unequivocally determined the stereochemistry of the thymine base in the title compound, C14H18N2O7. The absolute stereochemistry was determined from the use of D-ribose as the starting material. There are two independent molecules in the (Z′ = 2) which exist as N—H⋯O hydrogen-bonded pairs in the crystal structure.
Related literature
The title compound was obtained during studies on the synthesis of the 5-carbon analogue of psicofuranine, a naturally occurring nucleoside. For related literature on psicofuranine, see: Schroeder & Hoeksema (1959); Smith et al. (1973); Garrett (1960). For anomeric bromination see: Probert et al. (2005); Smith et al. (1999). For the extiction correction, see: Larson (1970).
Experimental
Crystal data
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Refinement
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Data collection: COLLECT (Nonius, 2001); cell DENZO/SCALEPACK (Otwinowski & Minor, 1997); data reduction: DENZO/SCALEPACK; program(s) used to solve structure: SIR92 (Altomare et al., 1994); program(s) used to refine structure: CRYSTALS (Betteridge et al., 2003); molecular graphics: CAMERON (Watkin et al., 1996); software used to prepare material for publication: CRYSTALS.
Supporting information
https://doi.org/10.1107/S1600536810001704/lh2979sup1.cif
contains datablocks global, I. DOI:Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S1600536810001704/lh2979Isup2.hkl
The title compound was recrystallized by diffusion from a mixture of methanol and acetone: m.p. 457–458 K; [α]D25 -235.2 (c, 0.84 in CHCl3).
In the absence of significant
Friedel pairs were merged and the was assigned from the use of D-ribose as the starting material.The H atoms were all located in a difference map, but those attached to carbon atoms were repositioned geometrically. The H atoms were initially refined with soft restraints on the bond lengths and angles to regularize their geometry (C—H in the range 0.93–0.98, N—H in the range 0.86–0.89 N—H to 0.86 O—H = 0.82 Å) and Uiso(H) (in the range 1.2–1.5 times Ueq of the parent atom), after which the positions were refined with riding constraints.
Nucleosides are a powerful class of anti-viral and anti-bacterial agents. Psicofuranine 1 (Fig. 1) is a naturally occurring nucleoside with a branch at the anomeric position of the sugar (Schroeder & Hoeksema, 1959). It has potent anti-bacterial and anti-tumour activity but is cardiotoxic in man (Smith et al., 1973). Psicofuranine is also unstable in acidic and basic conditions with the N-glycosidic bond readily undergoing hydrolytic cleavage (Garrett, 1960). During studies on the synthesis of the 5-carbon analogue of psicofuranine 2 the ester 4 was synthesized. Anomeric radical bromination (Smith et al., 1999) gave rise to a single isolable bromide 5 (Probert et al., 2005) which on displacement with silylated thymine gave a single nucleoside product. The stereochemistry at the anomeric position of the sugar was firmly established by X-ray crystallography and the structure was confirmed as 6 in which the thymine is in the α rather than the desired β position.
There are two crystallographically distinct molecules in the
which are related by a pseudo 2-fold rotation axis (Fig 2). When the two molecules are mapped they show good overlap (Fig. 3) with RMS deviations of 0.1055 on the positions, 0.082 for the bonds and 3.8892 for the torsion angles. These two molecules form hydrogen bonded pairs in the (Fig. 4, Fig. 5). In both cases the central nitrogen (N3, N26) between the two carbonyls of the thymine acts as the donor but hydrogen bonds are formed to different carbonyls of the two thymine rings. The absolute stereochemistry was determined from the use of D-ribose as the starting material. Only classical hydrogen bonding was considered.The title compound was obtained during studies on the synthesis of the
5-carbon analogue of psicofuranine, a naturally occurring nucleoside. For related literature on psicofuranine, see: Schroeder & Hoeksema (1959); Smith et al. (1973); Garrett (1960). For anomeric bromination see: Probert et al. (2005); Smith et al. (1999). For the extiction correction, see:, see: Larson (1970).
Data collection: COLLECT (Nonius, 2001); cell
DENZO/SCALEPACK (Otwinowski & Minor, 1997); data reduction: DENZO/SCALEPACK (Otwinowski & Minor, 1997); program(s) used to solve structure: SIR92 (Altomare et al., 1994); program(s) used to refine structure: CRYSTALS (Betteridge et al., 2003); molecular graphics: CAMERON (Watkin et al., 1996); software used to prepare material for publication: CRYSTALS (Betteridge et al., 2003).C14H18N2O7 | F(000) = 688 |
Mr = 326.31 | Dx = 1.418 Mg m−3 |
Monoclinic, P21 | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: P 2yb | Cell parameters from 2763 reflections |
a = 7.8937 (5) Å | θ = 5–26° |
b = 13.3471 (10) Å | µ = 0.12 mm−1 |
c = 14.9208 (10) Å | T = 150 K |
β = 103.565 (4)° | Plate, colourless |
V = 1528.17 (18) Å3 | 0.40 × 0.20 × 0.03 mm |
Z = 4 |
Nonius KappaCCD diffractometer | 2453 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.065 |
ω scans | θmax = 26.1°, θmin = 5.2° |
Absorption correction: multi-scan (DENZO/SCALEPACK; Otwinowski & Minor, 1997) | h = −9→9 |
Tmin = 0.83, Tmax = 1.00 | k = −14→16 |
9120 measured reflections | l = −18→18 |
3090 independent reflections |
Refinement on F2 | Hydrogen site location: inferred from neighbouring sites |
Least-squares matrix: full | H-atom parameters constrained |
R[F2 > 2σ(F2)] = 0.047 | Method = Modified Sheldrick w = 1/[σ2(F2) + (0.04P)2 + 0.5P], where P = (max(Fo2,0) + 2Fc2)/3 |
wR(F2) = 0.114 | (Δ/σ)max = 0.000161 |
S = 0.95 | Δρmax = 0.34 e Å−3 |
3090 reflections | Δρmin = −0.31 e Å−3 |
416 parameters | Extinction correction: Larson (1970), Equation 22 |
1 restraint | Extinction coefficient: 590 (70) |
Primary atom site location: structure-invariant direct methods |
C14H18N2O7 | V = 1528.17 (18) Å3 |
Mr = 326.31 | Z = 4 |
Monoclinic, P21 | Mo Kα radiation |
a = 7.8937 (5) Å | µ = 0.12 mm−1 |
b = 13.3471 (10) Å | T = 150 K |
c = 14.9208 (10) Å | 0.40 × 0.20 × 0.03 mm |
β = 103.565 (4)° |
Nonius KappaCCD diffractometer | 3090 independent reflections |
Absorption correction: multi-scan (DENZO/SCALEPACK; Otwinowski & Minor, 1997) | 2453 reflections with I > 2σ(I) |
Tmin = 0.83, Tmax = 1.00 | Rint = 0.065 |
9120 measured reflections |
R[F2 > 2σ(F2)] = 0.047 | 1 restraint |
wR(F2) = 0.114 | H-atom parameters constrained |
S = 0.95 | Δρmax = 0.34 e Å−3 |
3090 reflections | Δρmin = −0.31 e Å−3 |
416 parameters |
x | y | z | Uiso*/Ueq | ||
O1 | 0.2931 (4) | 0.3816 (2) | 0.81712 (19) | 0.0363 | |
C2 | 0.3274 (5) | 0.3347 (3) | 0.8903 (3) | 0.0308 | |
N3 | 0.3044 (5) | 0.3728 (3) | 0.9715 (2) | 0.0346 | |
C4 | 0.3343 (6) | 0.3220 (3) | 1.0559 (3) | 0.0348 | |
O5 | 0.3097 (4) | 0.3655 (2) | 1.1245 (2) | 0.0414 | |
C6 | 0.3964 (5) | 0.2203 (3) | 1.0536 (3) | 0.0336 | |
C7 | 0.4220 (5) | 0.1836 (3) | 0.9739 (3) | 0.0321 | |
N8 | 0.3912 (4) | 0.2388 (2) | 0.8940 (2) | 0.0290 | |
C9 | 0.4110 (5) | 0.1982 (3) | 0.8058 (3) | 0.0292 | |
O10 | 0.5057 (4) | 0.10739 (19) | 0.82495 (18) | 0.0320 | |
C11 | 0.4357 (5) | 0.0365 (3) | 0.7525 (3) | 0.0348 | |
C12 | 0.2451 (5) | 0.0597 (3) | 0.7235 (3) | 0.0343 | |
C13 | 0.2338 (5) | 0.1728 (3) | 0.7383 (3) | 0.0320 | |
O14 | 0.0903 (4) | 0.1860 (2) | 0.7798 (2) | 0.0374 | |
C15 | 0.0163 (5) | 0.0881 (3) | 0.7891 (3) | 0.0356 | |
O16 | 0.1544 (4) | 0.0203 (2) | 0.7876 (2) | 0.0362 | |
C17 | −0.1363 (6) | 0.0703 (3) | 0.7081 (3) | 0.0455 | |
C18 | −0.0325 (6) | 0.0826 (4) | 0.8799 (3) | 0.0469 | |
C19 | 0.5238 (5) | 0.2679 (3) | 0.7618 (3) | 0.0324 | |
O20 | 0.5064 (4) | 0.2774 (2) | 0.6798 (2) | 0.0417 | |
O21 | 0.6543 (4) | 0.3076 (2) | 0.8269 (2) | 0.0380 | |
C22 | 0.7785 (6) | 0.3686 (4) | 0.7933 (3) | 0.0443 | |
C23 | 0.4312 (7) | 0.1600 (4) | 1.1418 (3) | 0.0465 | |
O24 | 0.2166 (4) | 0.5799 (2) | 0.93916 (19) | 0.0374 | |
C25 | 0.1273 (5) | 0.6136 (3) | 0.8657 (3) | 0.0313 | |
N26 | 0.0825 (5) | 0.5521 (2) | 0.7891 (2) | 0.0323 | |
C27 | −0.0261 (5) | 0.5758 (3) | 0.7053 (3) | 0.0310 | |
O28 | −0.0626 (4) | 0.5168 (2) | 0.64081 (19) | 0.0375 | |
N29 | −0.0943 (5) | 0.6715 (2) | 0.6997 (2) | 0.0306 | |
C30 | −0.0454 (5) | 0.7396 (3) | 0.7711 (3) | 0.0326 | |
C31 | 0.0618 (5) | 0.7156 (3) | 0.8524 (3) | 0.0305 | |
C32 | 0.1154 (7) | 0.7889 (3) | 0.9308 (3) | 0.0461 | |
C33 | −0.2093 (5) | 0.6978 (3) | 0.6101 (3) | 0.0305 | |
O34 | −0.2864 (4) | 0.7906 (2) | 0.62183 (18) | 0.0339 | |
C35 | −0.3007 (6) | 0.8493 (3) | 0.5385 (3) | 0.0351 | |
C36 | −0.1471 (5) | 0.8204 (3) | 0.5013 (3) | 0.0333 | |
C37 | −0.1111 (5) | 0.7103 (3) | 0.5318 (3) | 0.0339 | |
O38 | 0.0732 (4) | 0.7037 (2) | 0.5655 (2) | 0.0364 | |
C39 | 0.1460 (6) | 0.7998 (3) | 0.5517 (3) | 0.0354 | |
O40 | 0.0075 (4) | 0.8694 (2) | 0.5505 (2) | 0.0368 | |
C41 | 0.2020 (6) | 0.8002 (4) | 0.4618 (3) | 0.0415 | |
C42 | 0.2914 (6) | 0.8224 (4) | 0.6342 (3) | 0.0473 | |
C43 | −0.3599 (6) | 0.6221 (3) | 0.5830 (3) | 0.0347 | |
O44 | −0.4208 (4) | 0.5954 (2) | 0.65563 (19) | 0.0351 | |
C45 | −0.5767 (6) | 0.5327 (3) | 0.6364 (3) | 0.0430 | |
O46 | −0.4246 (4) | 0.5982 (2) | 0.5041 (2) | 0.0448 | |
H71 | 0.4624 | 0.1181 | 0.9722 | 0.0371* | |
H111 | 0.4513 | −0.0316 | 0.7764 | 0.0408* | |
H112 | 0.4950 | 0.0448 | 0.7026 | 0.0412* | |
H121 | 0.1912 | 0.0372 | 0.6595 | 0.0412* | |
H131 | 0.2163 | 0.2111 | 0.6801 | 0.0380* | |
H172 | −0.1903 | 0.0060 | 0.7168 | 0.0643* | |
H173 | −0.0963 | 0.0702 | 0.6514 | 0.0642* | |
H171 | −0.2232 | 0.1235 | 0.7066 | 0.0639* | |
H181 | −0.0780 | 0.0161 | 0.8871 | 0.0748* | |
H183 | 0.0704 | 0.0951 | 0.9291 | 0.0752* | |
H182 | −0.1213 | 0.1339 | 0.8809 | 0.0750* | |
H222 | 0.8569 | 0.3999 | 0.8455 | 0.0703* | |
H221 | 0.8444 | 0.3287 | 0.7598 | 0.0705* | |
H223 | 0.7183 | 0.4210 | 0.7528 | 0.0699* | |
H232 | 0.4644 | 0.0921 | 1.1292 | 0.0681* | |
H233 | 0.3276 | 0.1583 | 1.1672 | 0.0683* | |
H231 | 0.5292 | 0.1900 | 1.1863 | 0.0683* | |
H301 | −0.0922 | 0.8051 | 0.7627 | 0.0356* | |
H323 | 0.0689 | 0.8550 | 0.9114 | 0.0654* | |
H322 | 0.2425 | 0.7918 | 0.9490 | 0.0654* | |
H321 | 0.0697 | 0.7671 | 0.9830 | 0.0652* | |
H351 | −0.4091 | 0.8324 | 0.4936 | 0.0382* | |
H352 | −0.2992 | 0.9212 | 0.5538 | 0.0381* | |
H361 | −0.1674 | 0.8283 | 0.4335 | 0.0381* | |
H371 | −0.1535 | 0.6632 | 0.4807 | 0.0422* | |
H412 | 0.2448 | 0.8668 | 0.4522 | 0.0641* | |
H411 | 0.2934 | 0.7499 | 0.4646 | 0.0643* | |
H413 | 0.1026 | 0.7836 | 0.4127 | 0.0639* | |
H421 | 0.3481 | 0.8846 | 0.6256 | 0.0668* | |
H422 | 0.3738 | 0.7673 | 0.6428 | 0.0670* | |
H423 | 0.2421 | 0.8276 | 0.6879 | 0.0672* | |
H453 | −0.6176 | 0.5238 | 0.6929 | 0.0613* | |
H452 | −0.5496 | 0.4674 | 0.6141 | 0.0609* | |
H451 | −0.6673 | 0.5654 | 0.5897 | 0.0615* | |
H261 | 0.1302 | 0.4919 | 0.7947 | 0.0383* | |
H31 | 0.2694 | 0.4353 | 0.9707 | 0.0413* |
U11 | U22 | U33 | U12 | U13 | U23 | |
O1 | 0.0473 (17) | 0.0277 (14) | 0.0351 (16) | 0.0081 (13) | 0.0120 (14) | 0.0074 (13) |
C2 | 0.034 (2) | 0.0255 (19) | 0.033 (2) | 0.0003 (17) | 0.0092 (18) | 0.0010 (18) |
N3 | 0.0444 (19) | 0.0259 (15) | 0.0338 (19) | 0.0032 (16) | 0.0095 (16) | −0.0002 (15) |
C4 | 0.034 (2) | 0.036 (2) | 0.035 (2) | −0.0036 (19) | 0.0083 (19) | −0.0014 (19) |
O5 | 0.0476 (18) | 0.0436 (17) | 0.0347 (16) | −0.0022 (16) | 0.0128 (14) | −0.0064 (15) |
C6 | 0.036 (2) | 0.035 (2) | 0.030 (2) | −0.0005 (19) | 0.0074 (18) | 0.0005 (18) |
C7 | 0.031 (2) | 0.032 (2) | 0.032 (2) | 0.0015 (17) | 0.0062 (18) | 0.0057 (17) |
N8 | 0.0345 (17) | 0.0266 (16) | 0.0267 (17) | 0.0057 (14) | 0.0090 (14) | 0.0010 (13) |
C9 | 0.034 (2) | 0.0221 (18) | 0.031 (2) | 0.0012 (17) | 0.0079 (18) | 0.0014 (16) |
O10 | 0.0344 (14) | 0.0229 (13) | 0.0370 (15) | 0.0019 (12) | 0.0052 (12) | −0.0029 (12) |
C11 | 0.036 (2) | 0.029 (2) | 0.040 (2) | −0.0002 (19) | 0.0102 (19) | −0.0074 (19) |
C12 | 0.035 (2) | 0.031 (2) | 0.037 (2) | 0.0000 (18) | 0.0094 (19) | −0.0027 (18) |
C13 | 0.037 (2) | 0.028 (2) | 0.031 (2) | 0.0029 (18) | 0.0078 (18) | 0.0004 (17) |
O14 | 0.0329 (16) | 0.0322 (15) | 0.0482 (18) | 0.0012 (13) | 0.0122 (14) | −0.0035 (13) |
C15 | 0.032 (2) | 0.0252 (19) | 0.048 (3) | −0.0016 (18) | 0.0082 (19) | −0.0045 (19) |
O16 | 0.0344 (16) | 0.0272 (14) | 0.0482 (18) | 0.0020 (13) | 0.0122 (14) | 0.0032 (13) |
C17 | 0.033 (2) | 0.043 (3) | 0.059 (3) | −0.002 (2) | 0.008 (2) | −0.007 (2) |
C18 | 0.044 (3) | 0.043 (2) | 0.057 (3) | 0.001 (2) | 0.018 (2) | 0.001 (2) |
C19 | 0.032 (2) | 0.0254 (19) | 0.041 (2) | 0.0035 (18) | 0.010 (2) | 0.0018 (18) |
O20 | 0.0489 (19) | 0.0462 (18) | 0.0318 (16) | −0.0022 (15) | 0.0131 (15) | 0.0039 (14) |
O21 | 0.0370 (16) | 0.0353 (15) | 0.0405 (16) | −0.0056 (14) | 0.0070 (14) | 0.0041 (13) |
C22 | 0.034 (2) | 0.041 (2) | 0.059 (3) | −0.009 (2) | 0.013 (2) | 0.010 (2) |
C23 | 0.055 (3) | 0.049 (3) | 0.036 (2) | 0.009 (2) | 0.011 (2) | 0.008 (2) |
O24 | 0.0423 (17) | 0.0327 (15) | 0.0333 (15) | 0.0038 (14) | 0.0012 (14) | 0.0006 (13) |
C25 | 0.029 (2) | 0.031 (2) | 0.033 (2) | −0.0001 (18) | 0.0057 (18) | 0.0009 (18) |
N26 | 0.0386 (19) | 0.0253 (16) | 0.0315 (19) | 0.0029 (15) | 0.0055 (16) | −0.0003 (14) |
C27 | 0.036 (2) | 0.0234 (18) | 0.034 (2) | −0.0007 (17) | 0.0077 (18) | −0.0008 (17) |
O28 | 0.0499 (18) | 0.0265 (14) | 0.0350 (16) | 0.0015 (14) | 0.0078 (14) | −0.0022 (13) |
N29 | 0.0365 (19) | 0.0266 (16) | 0.0277 (17) | 0.0020 (15) | 0.0054 (15) | −0.0005 (14) |
C30 | 0.037 (2) | 0.0256 (19) | 0.034 (2) | 0.0014 (17) | 0.0056 (19) | −0.0034 (17) |
C31 | 0.035 (2) | 0.0270 (19) | 0.029 (2) | 0.0006 (18) | 0.0081 (18) | −0.0037 (17) |
C32 | 0.056 (3) | 0.033 (2) | 0.043 (3) | 0.004 (2) | −0.002 (2) | −0.007 (2) |
C33 | 0.038 (2) | 0.0236 (18) | 0.030 (2) | 0.0053 (17) | 0.0075 (18) | 0.0003 (16) |
O34 | 0.0431 (17) | 0.0279 (14) | 0.0313 (14) | 0.0063 (13) | 0.0101 (14) | 0.0035 (12) |
C35 | 0.041 (2) | 0.029 (2) | 0.033 (2) | 0.0036 (19) | 0.0027 (19) | 0.0061 (17) |
C36 | 0.035 (2) | 0.030 (2) | 0.031 (2) | 0.0022 (18) | 0.0020 (18) | 0.0027 (17) |
C37 | 0.040 (2) | 0.0294 (19) | 0.032 (2) | −0.0002 (19) | 0.0082 (19) | −0.0040 (18) |
O38 | 0.0371 (16) | 0.0274 (14) | 0.0451 (17) | 0.0044 (13) | 0.0107 (14) | 0.0032 (13) |
C39 | 0.043 (3) | 0.0258 (19) | 0.039 (2) | 0.0027 (19) | 0.013 (2) | 0.0005 (18) |
O40 | 0.0356 (15) | 0.0291 (13) | 0.0456 (17) | 0.0016 (13) | 0.0092 (14) | −0.0033 (13) |
C41 | 0.041 (3) | 0.046 (2) | 0.040 (2) | −0.002 (2) | 0.016 (2) | 0.002 (2) |
C42 | 0.041 (3) | 0.050 (3) | 0.048 (3) | 0.004 (2) | 0.007 (2) | −0.009 (2) |
C43 | 0.038 (2) | 0.030 (2) | 0.036 (2) | 0.0048 (19) | 0.008 (2) | −0.0004 (18) |
O44 | 0.0372 (16) | 0.0325 (15) | 0.0353 (15) | −0.0068 (13) | 0.0081 (13) | −0.0031 (13) |
C45 | 0.045 (3) | 0.033 (2) | 0.051 (3) | −0.011 (2) | 0.012 (2) | −0.001 (2) |
O46 | 0.0479 (18) | 0.0505 (18) | 0.0323 (15) | −0.0102 (16) | 0.0022 (14) | −0.0051 (16) |
O1—C2 | 1.233 (5) | O24—C25 | 1.240 (5) |
C2—N3 | 1.365 (5) | C25—N26 | 1.384 (5) |
C2—N8 | 1.371 (5) | C25—C31 | 1.453 (5) |
N3—C4 | 1.401 (5) | N26—C27 | 1.377 (5) |
N3—H31 | 0.877 | N26—H261 | 0.882 |
C4—O5 | 1.230 (5) | C27—O28 | 1.224 (5) |
C4—C6 | 1.448 (6) | C27—N29 | 1.380 (5) |
C6—C7 | 1.345 (6) | N29—C30 | 1.385 (5) |
C6—C23 | 1.512 (6) | N29—C33 | 1.471 (5) |
C7—N8 | 1.374 (5) | C30—C31 | 1.346 (5) |
C7—H71 | 0.933 | C30—H301 | 0.946 |
N8—C9 | 1.464 (5) | C31—C32 | 1.507 (6) |
C9—O10 | 1.418 (5) | C32—H323 | 0.973 |
C9—C13 | 1.557 (6) | C32—H322 | 0.977 |
C9—C19 | 1.537 (5) | C32—H321 | 0.977 |
O10—C11 | 1.445 (5) | C33—O34 | 1.408 (5) |
C11—C12 | 1.497 (6) | C33—C37 | 1.555 (5) |
C11—H111 | 0.974 | C33—C43 | 1.541 (6) |
C11—H112 | 0.974 | O34—C35 | 1.452 (5) |
C12—C13 | 1.532 (5) | C35—C36 | 1.497 (6) |
C12—O16 | 1.423 (5) | C35—H351 | 0.981 |
C12—H121 | 0.996 | C35—H352 | 0.986 |
C13—O14 | 1.424 (5) | C36—C37 | 1.544 (6) |
C13—H131 | 0.988 | C36—O40 | 1.427 (5) |
O14—C15 | 1.452 (5) | C36—H361 | 0.992 |
C15—O16 | 1.420 (5) | C37—O38 | 1.426 (5) |
C15—C17 | 1.512 (6) | C37—H371 | 0.985 |
C15—C18 | 1.496 (6) | O38—C39 | 1.440 (5) |
C17—H172 | 0.981 | C39—O40 | 1.431 (5) |
C17—H173 | 0.969 | C39—C41 | 1.507 (6) |
C17—H171 | 0.984 | C39—C42 | 1.504 (6) |
C18—H181 | 0.974 | C41—H412 | 0.974 |
C18—H183 | 0.973 | C41—H411 | 0.979 |
C18—H182 | 0.982 | C41—H413 | 0.965 |
C19—O20 | 1.205 (5) | C42—H421 | 0.966 |
C19—O21 | 1.348 (5) | C42—H422 | 0.971 |
O21—C22 | 1.451 (5) | C42—H423 | 0.972 |
C22—H222 | 0.969 | C43—O44 | 1.333 (5) |
C22—H221 | 0.962 | C43—O46 | 1.210 (5) |
C22—H223 | 0.972 | O44—C45 | 1.460 (5) |
C23—H232 | 0.974 | C45—H453 | 0.979 |
C23—H233 | 0.979 | C45—H452 | 0.975 |
C23—H231 | 0.979 | C45—H451 | 0.977 |
O1—C2—N3 | 123.3 (4) | O24—C25—N26 | 119.7 (4) |
O1—C2—N8 | 120.7 (3) | O24—C25—C31 | 124.8 (4) |
N3—C2—N8 | 115.9 (3) | N26—C25—C31 | 115.5 (3) |
C2—N3—C4 | 126.0 (3) | C25—N26—C27 | 126.7 (3) |
C2—N3—H31 | 116.7 | C25—N26—H261 | 116.2 |
C4—N3—H31 | 117.3 | C27—N26—H261 | 117.2 |
N3—C4—O5 | 119.6 (4) | N26—C27—O28 | 123.2 (3) |
N3—C4—C6 | 114.8 (4) | N26—C27—N29 | 114.8 (3) |
O5—C4—C6 | 125.6 (4) | O28—C27—N29 | 122.0 (4) |
C4—C6—C7 | 119.0 (4) | C27—N29—C30 | 121.7 (3) |
C4—C6—C23 | 118.2 (4) | C27—N29—C33 | 115.2 (3) |
C7—C6—C23 | 122.8 (4) | C30—N29—C33 | 122.9 (3) |
C6—C7—N8 | 122.6 (4) | N29—C30—C31 | 122.7 (4) |
C6—C7—H71 | 119.2 | N29—C30—H301 | 118.4 |
N8—C7—H71 | 118.2 | C31—C30—H301 | 118.9 |
C7—N8—C2 | 121.6 (3) | C25—C31—C30 | 118.3 (4) |
C7—N8—C9 | 123.1 (3) | C25—C31—C32 | 118.5 (4) |
C2—N8—C9 | 115.2 (3) | C30—C31—C32 | 123.2 (4) |
N8—C9—O10 | 107.4 (3) | C31—C32—H323 | 110.0 |
N8—C9—C13 | 113.1 (3) | C31—C32—H322 | 108.9 |
O10—C9—C13 | 107.2 (3) | H323—C32—H322 | 109.8 |
N8—C9—C19 | 110.8 (3) | C31—C32—H321 | 109.6 |
O10—C9—C19 | 105.8 (3) | H323—C32—H321 | 108.8 |
C13—C9—C19 | 112.2 (3) | H322—C32—H321 | 109.7 |
C9—O10—C11 | 108.5 (3) | N29—C33—O34 | 106.9 (3) |
O10—C11—C12 | 105.3 (3) | N29—C33—C37 | 113.4 (3) |
O10—C11—H111 | 110.1 | O34—C33—C37 | 107.8 (3) |
C12—C11—H111 | 109.3 | N29—C33—C43 | 110.8 (3) |
O10—C11—H112 | 109.2 | O34—C33—C43 | 106.3 (3) |
C12—C11—H112 | 112.7 | C37—C33—C43 | 111.2 (3) |
H111—C11—H112 | 110.1 | C33—O34—C35 | 108.5 (3) |
C11—C12—C13 | 104.5 (3) | O34—C35—C36 | 105.7 (3) |
C11—C12—O16 | 111.1 (3) | O34—C35—H351 | 109.9 |
C13—C12—O16 | 102.2 (3) | C36—C35—H351 | 109.9 |
C11—C12—H121 | 112.9 | O34—C35—H352 | 109.4 |
C13—C12—H121 | 114.1 | C36—C35—H352 | 111.7 |
O16—C12—H121 | 111.4 | H351—C35—H352 | 110.1 |
C12—C13—C9 | 103.5 (3) | C35—C36—C37 | 104.2 (3) |
C12—C13—O14 | 105.3 (3) | C35—C36—O40 | 111.1 (3) |
C9—C13—O14 | 112.2 (3) | C37—C36—O40 | 102.1 (3) |
C12—C13—H131 | 112.6 | C35—C36—H361 | 113.5 |
C9—C13—H131 | 112.0 | C37—C36—H361 | 112.1 |
O14—C13—H131 | 110.9 | O40—C36—H361 | 112.9 |
C13—O14—C15 | 108.0 (3) | C36—C37—C33 | 103.5 (3) |
O14—C15—O16 | 104.2 (3) | C36—C37—O38 | 105.3 (3) |
O14—C15—C17 | 109.1 (3) | C33—C37—O38 | 112.1 (3) |
O16—C15—C17 | 111.0 (3) | C36—C37—H371 | 111.9 |
O14—C15—C18 | 109.0 (3) | C33—C37—H371 | 112.0 |
O16—C15—C18 | 110.2 (4) | O38—C37—H371 | 111.5 |
C17—C15—C18 | 113.0 (4) | C37—O38—C39 | 107.7 (3) |
C12—O16—C15 | 106.6 (3) | O38—C39—O40 | 104.5 (3) |
C15—C17—H172 | 108.7 | O38—C39—C41 | 109.9 (3) |
C15—C17—H173 | 109.6 | O40—C39—C41 | 111.7 (3) |
H172—C17—H173 | 110.8 | O38—C39—C42 | 108.4 (4) |
C15—C17—H171 | 109.0 | O40—C39—C42 | 108.3 (3) |
H172—C17—H171 | 108.2 | C41—C39—C42 | 113.7 (4) |
H173—C17—H171 | 110.5 | C39—O40—C36 | 105.5 (3) |
C15—C18—H181 | 108.9 | C39—C41—H412 | 108.6 |
C15—C18—H183 | 109.1 | C39—C41—H411 | 109.1 |
H181—C18—H183 | 109.7 | H412—C41—H411 | 110.7 |
C15—C18—H182 | 108.4 | C39—C41—H413 | 108.6 |
H181—C18—H182 | 110.6 | H412—C41—H413 | 110.2 |
H183—C18—H182 | 110.0 | H411—C41—H413 | 109.6 |
C9—C19—O20 | 123.9 (4) | C39—C42—H421 | 110.6 |
C9—C19—O21 | 110.5 (3) | C39—C42—H422 | 108.4 |
O20—C19—O21 | 125.2 (4) | H421—C42—H422 | 110.6 |
C19—O21—C22 | 115.8 (3) | C39—C42—H423 | 108.2 |
O21—C22—H222 | 108.7 | H421—C42—H423 | 109.6 |
O21—C22—H221 | 111.1 | H422—C42—H423 | 109.4 |
H222—C22—H221 | 109.6 | C33—C43—O44 | 111.4 (3) |
O21—C22—H223 | 110.3 | C33—C43—O46 | 123.5 (4) |
H222—C22—H223 | 108.4 | O44—C43—O46 | 124.8 (4) |
H221—C22—H223 | 108.7 | C43—O44—C45 | 116.2 (3) |
C6—C23—H232 | 109.2 | O44—C45—H453 | 109.5 |
C6—C23—H233 | 110.6 | O44—C45—H452 | 109.7 |
H232—C23—H233 | 109.9 | H453—C45—H452 | 109.2 |
C6—C23—H231 | 109.0 | O44—C45—H451 | 109.1 |
H232—C23—H231 | 107.9 | H453—C45—H451 | 109.6 |
H233—C23—H231 | 110.3 | H452—C45—H451 | 109.8 |
D—H···A | D—H | H···A | D···A | D—H···A |
C11—H111···O5i | 0.97 | 2.52 | 3.301 (6) | 138 |
N26—H261···O1 | 0.88 | 1.93 | 2.791 (6) | 164 |
N3—H31···O24 | 0.88 | 2.01 | 2.863 (6) | 165 |
Symmetry code: (i) −x+1, y−1/2, −z+2. |
Experimental details
Crystal data | |
Chemical formula | C14H18N2O7 |
Mr | 326.31 |
Crystal system, space group | Monoclinic, P21 |
Temperature (K) | 150 |
a, b, c (Å) | 7.8937 (5), 13.3471 (10), 14.9208 (10) |
β (°) | 103.565 (4) |
V (Å3) | 1528.17 (18) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 0.12 |
Crystal size (mm) | 0.40 × 0.20 × 0.03 |
Data collection | |
Diffractometer | Nonius KappaCCD |
Absorption correction | Multi-scan (DENZO/SCALEPACK; Otwinowski & Minor, 1997) |
Tmin, Tmax | 0.83, 1.00 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 9120, 3090, 2453 |
Rint | 0.065 |
(sin θ/λ)max (Å−1) | 0.618 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.047, 0.114, 0.95 |
No. of reflections | 3090 |
No. of parameters | 416 |
No. of restraints | 1 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.34, −0.31 |
Computer programs: COLLECT (Nonius, 2001), DENZO/SCALEPACK (Otwinowski & Minor, 1997), SIR92 (Altomare et al., 1994), CRYSTALS (Betteridge et al., 2003), CAMERON (Watkin et al., 1996).
D—H···A | D—H | H···A | D···A | D—H···A |
N26—H261···O1 | 0.88 | 1.93 | 2.791 (6) | 164 |
N3—H31···O24 | 0.88 | 2.01 | 2.863 (6) | 165 |
Acknowledgements
We would like to thank the Chemical Crystallography department and ALT at Oxford University for use of the diffractometers.
References
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Nucleosides are a powerful class of anti-viral and anti-bacterial agents. Psicofuranine 1 (Fig. 1) is a naturally occurring nucleoside with a branch at the anomeric position of the sugar (Schroeder & Hoeksema, 1959). It has potent anti-bacterial and anti-tumour activity but is cardiotoxic in man (Smith et al., 1973). Psicofuranine is also unstable in acidic and basic conditions with the N-glycosidic bond readily undergoing hydrolytic cleavage (Garrett, 1960). During studies on the synthesis of the 5-carbon analogue of psicofuranine 2 the ester 4 was synthesized. Anomeric radical bromination (Smith et al., 1999) gave rise to a single isolable bromide 5 (Probert et al., 2005) which on displacement with silylated thymine gave a single nucleoside product. The stereochemistry at the anomeric position of the sugar was firmly established by X-ray crystallography and the structure was confirmed as 6 in which the thymine is in the α rather than the desired β position.
There are two crystallographically distinct molecules in the asymmetric unit which are related by a pseudo 2-fold rotation axis (Fig 2). When the two molecules are mapped they show good overlap (Fig. 3) with RMS deviations of 0.1055 on the positions, 0.082 for the bonds and 3.8892 for the torsion angles. These two molecules form hydrogen bonded pairs in the crystal structure (Fig. 4, Fig. 5). In both cases the central nitrogen (N3, N26) between the two carbonyls of the thymine acts as the donor but hydrogen bonds are formed to different carbonyls of the two thymine rings. The absolute stereochemistry was determined from the use of D-ribose as the starting material. Only classical hydrogen bonding was considered.