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The title compound, C29H36O10·2C2H6OS, forms a monoclinic crystal containing two hydrogen-bonded dimethyl sulfoxide molecules per 10-deacetyl baccatin III. The lattice is further stabilized by two additional hydrogen bonds and a dipole-dipole interaction. A comparison of 10-deacetyl baccatin III with the structurally similar docetaxel reveals differences primarily in the benzoyl moiety, while comparisons to baccatin III identify relative differences principally in the cyclooctane- and cyclohexane-ring conformations.
Supporting information
CCDC reference: 158250
Crystals of 10-deacetyl baccatin III were obtained by vacuum evaporation (200 mm H g) of a dimethyl sulfoxide solution.
All non-hydrogen atoms were refined anisotropically except for S1C, O1C and C2C.
These disordered atoms were assigned to the disordered DMSO of lower
occupancy. Hydroxy H atoms were located in a difference map and their
isotropic displacement parameters were refined. All other H atoms were refined
using a riding model and equivalent isotropic parameters selected to
correspond with their adjacent carbons (1.5 x Ueq for methyl H atoms,
1.2 x Ueq for the remaining H atoms). H atoms of the disordered DMSO
molecule were not included in the refinement.
Data collection: Bruker Software; cell refinement: Bruker Software; data reduction: Bruker Software; program(s) used to solve structure: SHELXTL/PC (Sheldrick, 1994); program(s) used to refine structure: SHELXTL/PC; molecular graphics: SHELXTL/PC; software used to prepare material for publication: SHELXTL/PC.
Crystal data top
C29H36O10·2C2H6OS | F(000) = 748 |
Mr = 700.83 | Dx = 1.327 Mg m−3 |
Monoclinic, P21 | Mo Kα radiation, λ = 0.71073 Å |
a = 9.3677 (10) Å | Cell parameters from 35 reflections |
b = 21.991 (4) Å | θ = 7–17° |
c = 9.4564 (11) Å | µ = 0.21 mm−1 |
β = 115.827 (9)° | T = 293 K |
V = 1753.5 (4) Å3 | Block, colorless |
Z = 2 | 0.5 × 0.4 × 0.3 mm |
Data collection top
Bruker P4 diffractometer | θmax = 27.5°, θmin = 1.9° |
θ–2θ var. scans | h = 0→12 |
4342 measured reflections | k = 0→28 |
4103 independent reflections | l = −11→11 |
3005 reflections with I > 2σ(I) | 3 standard reflections every 97 reflections |
Rint = 0.025 | intensity decay: <2.0 |
Refinement top
Refinement on F2 | H atoms treated by a mixture of independent and constrained refinement |
Least-squares matrix: full | Calculated w = 1/[σ2(Fo2) + (0.0775P)2 + 0.4816P] where P = (Fo2 + 2Fc2)/3 |
R[F2 > 2σ(F2)] = 0.056 | (Δ/σ)max < 0.001 |
wR(F2) = 0.136 | Δρmax = 0.34 e Å−3 |
4100 reflections | Δρmin = −0.26 e Å−3 |
436 parameters | Absolute structure: Flack (1983) |
1 restraint | Absolute structure parameter: 0.08 (15) |
Crystal data top
C29H36O10·2C2H6OS | V = 1753.5 (4) Å3 |
Mr = 700.83 | Z = 2 |
Monoclinic, P21 | Mo Kα radiation |
a = 9.3677 (10) Å | µ = 0.21 mm−1 |
b = 21.991 (4) Å | T = 293 K |
c = 9.4564 (11) Å | 0.5 × 0.4 × 0.3 mm |
β = 115.827 (9)° | |
Data collection top
Bruker P4 diffractometer | Rint = 0.025 |
4342 measured reflections | 3 standard reflections every 97 reflections |
4103 independent reflections | intensity decay: <2.0 |
3005 reflections with I > 2σ(I) | |
Refinement top
R[F2 > 2σ(F2)] = 0.056 | H atoms treated by a mixture of independent and constrained refinement |
wR(F2) = 0.136 | Δρmax = 0.34 e Å−3 |
4100 reflections | Δρmin = −0.26 e Å−3 |
436 parameters | Absolute structure: Flack (1983) |
1 restraint | Absolute structure parameter: 0.08 (15) |
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. |
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top | x | y | z | Uiso*/Ueq | Occ. (<1) |
C1 | 0.6310 (5) | 0.2074 (2) | 0.5046 (5) | 0.0420 (10) | |
O1 | 0.5923 (5) | 0.2701 (2) | 0.4835 (4) | 0.0581 (9) | |
H1 | 0.5023 | 0.2801 | 0.3993 | 0.09 (2)* | |
C2 | 0.7822 (5) | 0.2068 (2) | 0.6661 (5) | 0.0347 (8) | |
H2A | 0.8618 | 0.2339 | 0.6587 | 0.042* | |
O2 | 0.7249 (4) | 0.23420 (13) | 0.7725 (3) | 0.0387 (7) | |
C3 | 0.8626 (4) | 0.1447 (2) | 0.7354 (4) | 0.0314 (8) | |
H3A | 0.7856 | 0.1133 | 0.6758 | 0.038* | |
C4 | 0.8916 (5) | 0.1369 (2) | 0.9088 (4) | 0.0348 (8) | |
O4 | 0.7408 (3) | 0.12433 (13) | 0.9117 (3) | 0.0371 (6) | |
C5 | 1.0229 (5) | 0.0948 (2) | 1.0202 (5) | 0.0471 (11) | |
H5A | 0.9803 | 0.0662 | 1.0714 | 0.057* | |
O5 | 1.1002 (4) | 0.1457 (2) | 1.1240 (4) | 0.0643 (10) | |
C6 | 1.1288 (6) | 0.0620 (3) | 0.9601 (5) | 0.0535 (12) | |
H6A | 1.2332 | 0.0804 | 1.0068 | 0.064* | |
H6B | 1.1402 | 0.0199 | 0.9942 | 0.064* | |
C7 | 1.0658 (5) | 0.0635 (2) | 0.7829 (5) | 0.0433 (10) | |
H7A | 0.9714 | 0.0377 | 0.7367 | 0.052* | |
O7 | 1.1837 (4) | 0.0394 (2) | 0.7427 (4) | 0.0619 (10) | |
H7 | 1.1403 | 0.0066 | 0.6698 | 0.08 (2)* | |
C8 | 1.0189 (5) | 0.1297 (2) | 0.7176 (5) | 0.0388 (9) | |
C9 | 0.9992 (5) | 0.1232 (2) | 0.5467 (5) | 0.0450 (10) | |
O9 | 1.1078 (4) | 0.1388 (2) | 0.5158 (4) | 0.0676 (11) | |
C10 | 0.8591 (5) | 0.0907 (2) | 0.4185 (5) | 0.0429 (10) | |
H10A | 0.8631 | 0.0482 | 0.4510 | 0.052* | |
O10 | 0.8759 (5) | 0.0910 (2) | 0.2762 (4) | 0.0622 (10) | |
H10 | 0.9607 | 0.0996 | 0.2975 | 0.05 (2)* | |
C11 | 0.7007 (5) | 0.1159 (2) | 0.3961 (5) | 0.0438 (11) | |
C12 | 0.5939 (5) | 0.0800 (2) | 0.4142 (5) | 0.0483 (11) | |
C13 | 0.4516 (6) | 0.1086 (2) | 0.4266 (6) | 0.0569 (14) | |
H13A | 0.3673 | 0.1149 | 0.3203 | 0.068* | |
O13 | 0.3946 (5) | 0.0683 (2) | 0.5089 (7) | 0.091 (2) | |
H13 | 0.3211 | 0.0887 | 0.5442 | 0.11 (3)* | |
C14 | 0.4945 (6) | 0.1707 (2) | 0.5119 (6) | 0.0494 (11) | |
H14A | 0.4002 | 0.1959 | 0.4693 | 0.059* | |
H14B | 0.5206 | 0.1637 | 0.6217 | 0.059* | |
C15 | 0.6696 (6) | 0.1842 (2) | 0.3691 (5) | 0.0486 (11) | |
C16 | 0.8019 (3) | 0.22277 (13) | 0.3618 (3) | 0.067 (2) | |
H16A | 0.7692 | 0.26455 | 0.3445 | 0.1* | |
H16B | 0.8239 | 0.20881 | 0.2771 | 0.1* | |
H16C | 0.8958 | 0.21917 | 0.4591 | 0.1* | |
C17 | 0.5242 (3) | 0.19368 (13) | 0.2076 (3) | 0.080 (2) | |
H17A | 0.4361 | 0.17047 | 0.2044 | 0.121* | |
H17B | 0.5504 | 0.18042 | 0.1250 | 0.121* | |
H17C | 0.4965 | 0.23602 | 0.1938 | 0.121* | |
C18 | 0.6025 (3) | 0.01178 (13) | 0.4276 (3) | 0.0646 (15) | |
H18A | 0.5121 | −0.00314 | 0.4397 | 0.097* | |
H18B | 0.6978 | 0.00023 | 0.5173 | 0.097* | |
H18C | 0.6030 | −0.00526 | 0.3343 | 0.097* | |
C19 | 1.1542 (3) | 0.17542 (13) | 0.8013 (3) | 0.0541 (12) | |
H19A | 1.1700 | 0.18065 | 0.9079 | 0.081* | |
H19B | 1.1271 | 0.21380 | 0.7477 | 0.081* | |
H19C | 1.2500 | 0.16032 | 0.8004 | 0.081* | |
C20 | 0.9747 (6) | 0.1869 (2) | 1.0293 (5) | 0.0461 (10) | |
H20A | 1.0110 | 0.2205 | 0.9870 | 0.055* | |
H20B | 0.9128 | 0.2015 | 1.0819 | 0.055* | |
C21 | 0.7596 (6) | 0.2922 (2) | 0.8122 (5) | 0.0428 (10) | |
O21 | 0.8668 (5) | 0.3194 (2) | 0.8025 (5) | 0.0641 (10) | |
C22 | 0.6525 (6) | 0.3203 (2) | 0.8732 (5) | 0.0474 (11) | |
C23 | 0.5216 (7) | 0.2909 (2) | 0.8711 (6) | 0.0570 (12) | |
H23A | 0.4975 | 0.2515 | 0.8320 | 0.068* | |
C24 | 0.4271 (8) | 0.3200 (3) | 0.9268 (8) | 0.073 (2) | |
H24A | 0.3369 | 0.3005 | 0.9221 | 0.088* | |
C25 | 0.4636 (9) | 0.3772 (3) | 0.9893 (9) | 0.081 (2) | |
H25A | 0.4001 | 0.3961 | 1.0291 | 0.097* | |
C26 | 0.5931 (10) | 0.4060 (4) | 0.9927 (12) | 0.107 (3) | |
H26A | 0.6176 | 0.4451 | 1.0339 | 0.129* | |
C27 | 0.6877 (9) | 0.3781 (3) | 0.9358 (10) | 0.086 (2) | |
H27A | 0.7766 | 0.3982 | 0.9394 | 0.103* | |
C28 | 0.6907 (6) | 0.0657 (2) | 0.8873 (6) | 0.0517 (12) | |
O28 | 0.7560 (5) | 0.0266 (2) | 0.8496 (5) | 0.0654 (10) | |
C29 | 0.5482 (8) | 0.0587 (3) | 0.9171 (9) | 0.078 (2) | |
H29A | 0.5208 | 0.0974 | 0.9455 | 0.118* | |
H29B | 0.5706 | 0.0303 | 1.0011 | 0.118* | |
H29C | 0.4612 | 0.0440 | 0.8237 | 0.118* | |
S1A | 1.0904 (2) | −0.09297 (7) | 0.4551 (2) | 0.0761 (5) | |
O1A | 1.0423 (7) | −0.0562 (3) | 0.5601 (7) | 0.103 (2) | |
C1A | 1.2993 (10) | −0.0881 (4) | 0.5339 (12) | 0.106 (3) | |
H1AA | 1.3463 | −0.1119 | 0.6281 | 0.159* | |
H1AB | 1.3315 | −0.0464 | 0.5577 | 0.159* | |
H1AC | 1.3336 | −0.1032 | 0.4585 | 0.159* | |
C2A | 1.0527 (17) | −0.0463 (5) | 0.2950 (13) | 0.143 (4) | |
H2AA | 0.9402 | −0.0426 | 0.2332 | 0.215* | |
H2AB | 1.0996 | −0.0636 | 0.2319 | 0.215* | |
H2AC | 1.0974 | −0.0068 | 0.3311 | 0.215* | |
S1B | 0.1547 (3) | 0.31854 (11) | 0.2668 (3) | 0.0750 (11) | 0.653 (7) |
O1B | 0.2802 (10) | 0.2893 (5) | 0.2377 (9) | 0.086 (2) | 0.653 (7) |
C1B | 0.149 (4) | 0.3937 (10) | 0.216 (4) | 0.183 (15) | 0.653 (7) |
C2B | 0.233 (2) | 0.3291 (12) | 0.4790 (17) | 0.153 (9) | 0.653 (7) |
S1C | 0.2544 (8) | 0.3565 (3) | 0.3366 (8) | 0.100 (3)* | 0.347 (7) |
O1C | 0.334 (2) | 0.3179 (9) | 0.262 (2) | 0.087 (5)* | 0.347 (7) |
C1C | 0.150 (3) | 0.2998 (11) | 0.403 (3) | 0.085 (6)* | 0.347 (7) |
C2C | 0.106 (4) | 0.3978 (19) | 0.206 (4) | 0.094 (9)* | 0.347 (7) |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
C1 | 0.051 (2) | 0.035 (2) | 0.038 (2) | 0.013 (2) | 0.018 (2) | −0.001 (2) |
O1 | 0.083 (3) | 0.039 (2) | 0.052 (2) | 0.020 (2) | 0.030 (2) | 0.0108 (15) |
C2 | 0.044 (2) | 0.030 (2) | 0.036 (2) | 0.001 (2) | 0.022 (2) | −0.003 (2) |
O2 | 0.054 (2) | 0.0308 (14) | 0.040 (2) | 0.0014 (13) | 0.0279 (14) | −0.0034 (12) |
C3 | 0.027 (2) | 0.036 (2) | 0.029 (2) | −0.001 (2) | 0.0108 (15) | −0.005 (2) |
C4 | 0.034 (2) | 0.041 (2) | 0.032 (2) | −0.001 (2) | 0.016 (2) | −0.001 (2) |
O4 | 0.0374 (14) | 0.038 (2) | 0.0418 (15) | 0.0007 (12) | 0.0227 (12) | 0.0027 (12) |
C5 | 0.039 (2) | 0.062 (3) | 0.033 (2) | 0.008 (2) | 0.009 (2) | 0.005 (2) |
O5 | 0.050 (2) | 0.085 (3) | 0.037 (2) | 0.008 (2) | −0.0010 (14) | −0.012 (2) |
C6 | 0.041 (2) | 0.068 (3) | 0.044 (2) | 0.020 (2) | 0.013 (2) | 0.006 (2) |
C7 | 0.031 (2) | 0.053 (3) | 0.045 (2) | 0.007 (2) | 0.016 (2) | −0.004 (2) |
O7 | 0.042 (2) | 0.079 (3) | 0.066 (2) | 0.016 (2) | 0.024 (2) | −0.013 (2) |
C8 | 0.035 (2) | 0.048 (2) | 0.035 (2) | −0.002 (2) | 0.017 (2) | −0.009 (2) |
C9 | 0.048 (2) | 0.050 (3) | 0.043 (2) | 0.009 (2) | 0.027 (2) | 0.004 (2) |
O9 | 0.066 (2) | 0.093 (3) | 0.064 (2) | −0.003 (2) | 0.047 (2) | −0.003 (2) |
C10 | 0.054 (3) | 0.043 (2) | 0.034 (2) | 0.012 (2) | 0.021 (2) | −0.003 (2) |
O10 | 0.075 (3) | 0.078 (3) | 0.042 (2) | 0.012 (2) | 0.033 (2) | −0.007 (2) |
C11 | 0.049 (2) | 0.049 (3) | 0.025 (2) | 0.016 (2) | 0.007 (2) | −0.005 (2) |
C12 | 0.042 (2) | 0.049 (3) | 0.043 (2) | 0.004 (2) | 0.008 (2) | −0.012 (2) |
C13 | 0.037 (2) | 0.056 (3) | 0.059 (3) | 0.005 (2) | 0.003 (2) | −0.017 (2) |
O13 | 0.071 (3) | 0.062 (3) | 0.165 (5) | −0.016 (2) | 0.073 (3) | −0.029 (3) |
C14 | 0.043 (2) | 0.048 (3) | 0.051 (3) | 0.011 (2) | 0.015 (2) | −0.003 (2) |
C15 | 0.064 (3) | 0.048 (3) | 0.032 (2) | 0.012 (2) | 0.020 (2) | 0.004 (2) |
C16 | 0.103 (4) | 0.053 (3) | 0.067 (3) | 0.017 (3) | 0.058 (3) | 0.011 (3) |
C17 | 0.107 (5) | 0.080 (4) | 0.035 (3) | 0.041 (4) | 0.013 (3) | 0.007 (3) |
C18 | 0.061 (3) | 0.044 (3) | 0.086 (4) | −0.002 (2) | 0.029 (3) | −0.021 (3) |
C19 | 0.041 (2) | 0.068 (3) | 0.059 (3) | −0.014 (2) | 0.027 (2) | −0.013 (2) |
C20 | 0.052 (3) | 0.052 (3) | 0.033 (2) | −0.005 (2) | 0.017 (2) | −0.010 (2) |
C21 | 0.058 (3) | 0.034 (2) | 0.041 (2) | 0.000 (2) | 0.026 (2) | −0.002 (2) |
O21 | 0.085 (3) | 0.043 (2) | 0.088 (3) | −0.021 (2) | 0.059 (2) | −0.016 (2) |
C22 | 0.066 (3) | 0.036 (2) | 0.046 (2) | 0.002 (2) | 0.030 (2) | −0.004 (2) |
C23 | 0.070 (3) | 0.041 (2) | 0.068 (3) | −0.002 (2) | 0.038 (3) | −0.009 (2) |
C24 | 0.074 (4) | 0.070 (4) | 0.092 (4) | 0.002 (3) | 0.052 (3) | −0.007 (3) |
C25 | 0.101 (5) | 0.068 (4) | 0.103 (5) | 0.020 (4) | 0.071 (4) | −0.009 (4) |
C26 | 0.132 (7) | 0.065 (4) | 0.167 (8) | −0.022 (4) | 0.104 (6) | −0.062 (5) |
C27 | 0.105 (5) | 0.051 (3) | 0.138 (6) | −0.021 (3) | 0.088 (5) | −0.039 (4) |
C28 | 0.045 (2) | 0.049 (3) | 0.060 (3) | −0.005 (2) | 0.022 (2) | 0.003 (2) |
O28 | 0.070 (2) | 0.041 (2) | 0.095 (3) | 0.003 (2) | 0.044 (2) | −0.006 (2) |
C29 | 0.067 (3) | 0.068 (4) | 0.120 (5) | −0.021 (3) | 0.059 (4) | −0.005 (4) |
S1A | 0.0987 (11) | 0.0532 (8) | 0.0962 (11) | −0.0088 (8) | 0.0609 (10) | −0.0188 (8) |
O1A | 0.121 (4) | 0.096 (4) | 0.131 (5) | −0.022 (3) | 0.090 (4) | −0.039 (3) |
C1A | 0.100 (5) | 0.083 (5) | 0.152 (8) | −0.005 (4) | 0.070 (6) | −0.031 (5) |
C2A | 0.217 (12) | 0.106 (7) | 0.131 (8) | 0.065 (8) | 0.099 (9) | 0.022 (6) |
S1B | 0.0575 (14) | 0.0519 (14) | 0.100 (2) | 0.0060 (11) | 0.0199 (12) | −0.0068 (12) |
O1B | 0.075 (5) | 0.082 (5) | 0.081 (5) | 0.030 (5) | 0.015 (4) | −0.014 (4) |
C1B | 0.26 (3) | 0.082 (11) | 0.31 (3) | 0.104 (15) | 0.22 (3) | 0.071 (14) |
C2B | 0.116 (11) | 0.26 (3) | 0.073 (8) | 0.075 (15) | 0.028 (8) | −0.009 (12) |
Geometric parameters (Å, º) top
C1—O1 | 1.417 (5) | C15—C16 | 1.528 (6) |
C1—C14 | 1.539 (7) | C15—C17 | 1.555 (5) |
C1—C15 | 1.561 (6) | C21—O21 | 1.205 (6) |
C1—C2 | 1.566 (6) | C21—C22 | 1.492 (6) |
C2—O2 | 1.460 (5) | C22—C23 | 1.379 (7) |
C2—C3 | 1.561 (6) | C22—C27 | 1.380 (7) |
O2—C21 | 1.330 (5) | C23—C24 | 1.369 (8) |
C3—C4 | 1.551 (5) | C24—C25 | 1.368 (10) |
C3—C8 | 1.579 (5) | C25—C26 | 1.358 (10) |
C4—O4 | 1.452 (5) | C26—C27 | 1.366 (9) |
C4—C20 | 1.529 (6) | C28—O28 | 1.196 (6) |
C4—C5 | 1.532 (6) | C28—C29 | 1.487 (7) |
O4—C28 | 1.357 (6) | S1A—O1A | 1.494 (5) |
C5—O5 | 1.456 (6) | S1A—C2A | 1.734 (11) |
C5—C6 | 1.523 (7) | S1A—C1A | 1.768 (8) |
O5—C20 | 1.444 (6) | S1B—S1C | 1.212 (7) |
C6—C7 | 1.515 (7) | S1B—C1C | 1.38 (3) |
C7—O7 | 1.418 (5) | S1B—O1B | 1.468 (8) |
C7—C8 | 1.567 (7) | S1B—O1C | 1.70 (2) |
C8—C19 | 1.540 (5) | S1B—C1B | 1.72 (2) |
C8—C9 | 1.551 (6) | S1B—C2B | 1.83 (2) |
C9—O9 | 1.223 (6) | S1B—C2C | 1.83 (4) |
C9—C10 | 1.522 (7) | O1B—O1C | 0.78 (2) |
C10—O10 | 1.421 (5) | O1B—S1C | 1.822 (11) |
C10—C11 | 1.509 (6) | C1B—S1C | 1.40 (3) |
C11—C12 | 1.343 (7) | C2B—C1C | 1.02 (3) |
C11—C15 | 1.530 (7) | C2B—S1C | 1.57 (2) |
C12—C18 | 1.505 (6) | S1C—O1C | 1.49 (2) |
C12—C13 | 1.524 (7) | S1C—C2C | 1.67 (4) |
C13—O13 | 1.428 (8) | S1C—C1C | 1.86 (3) |
C13—C14 | 1.548 (7) | | |
| | | |
O1—C1—C14 | 110.5 (4) | C26—C25—C24 | 119.5 (6) |
O1—C1—C15 | 109.9 (4) | C25—C26—C27 | 120.4 (6) |
C14—C1—C15 | 111.1 (4) | C26—C27—C22 | 120.6 (6) |
O1—C1—C2 | 102.2 (3) | O28—C28—O4 | 123.4 (4) |
C14—C1—C2 | 111.6 (4) | O28—C28—C29 | 126.9 (5) |
C15—C1—C2 | 111.3 (4) | O4—C28—C29 | 109.7 (5) |
O2—C2—C3 | 109.1 (3) | O1A—S1A—C2A | 104.7 (4) |
O2—C2—C1 | 102.8 (3) | O1A—S1A—C1A | 106.6 (4) |
C3—C2—C1 | 118.8 (3) | C2A—S1A—C1A | 95.7 (6) |
C21—O2—C2 | 118.1 (3) | S1C—S1B—C1C | 91.7 (11) |
C4—C3—C2 | 111.7 (3) | S1C—S1B—O1B | 85.1 (5) |
C4—C3—C8 | 110.3 (3) | C1C—S1B—O1B | 113.7 (11) |
C2—C3—C8 | 116.0 (3) | S1C—S1B—O1C | 58.9 (8) |
O4—C4—C20 | 107.9 (3) | C1C—S1B—O1C | 117.3 (12) |
O4—C4—C5 | 111.6 (3) | O1B—S1B—O1C | 27.1 (6) |
C20—C4—C5 | 85.8 (3) | S1C—S1B—C1B | 54.0 (13) |
O4—C4—C3 | 108.5 (3) | C1C—S1B—C1B | 122.9 (14) |
C20—C4—C3 | 120.4 (3) | O1B—S1B—C1B | 107.5 (9) |
C5—C4—C3 | 120.8 (3) | O1C—S1B—C1B | 85.0 (11) |
C28—O4—C4 | 116.4 (3) | S1C—S1B—C2B | 58.0 (9) |
O5—C5—C6 | 113.7 (4) | C1C—S1B—C2B | 33.7 (12) |
O5—C5—C4 | 90.8 (4) | O1B—S1B—C2B | 107.0 (6) |
C6—C5—C4 | 119.2 (4) | O1C—S1B—C2B | 95.8 (9) |
C20—O5—C5 | 91.8 (3) | C1B—S1B—C2B | 97.8 (14) |
C7—C6—C5 | 113.5 (4) | S1C—S1B—C2C | 62.7 (11) |
O7—C7—C6 | 108.3 (4) | C1C—S1B—C2C | 118.5 (15) |
O7—C7—C8 | 111.1 (4) | O1B—S1B—C2C | 117.8 (13) |
C6—C7—C8 | 111.4 (4) | O1C—S1B—C2C | 96.4 (14) |
C19—C8—C9 | 107.1 (3) | C1B—S1B—C2C | 11.6 (18) |
C19—C8—C7 | 112.2 (3) | C2B—S1B—C2C | 98.8 (13) |
C9—C8—C7 | 102.2 (3) | O1C—O1B—S1B | 93.2 (16) |
C19—C8—C3 | 113.8 (3) | O1C—O1B—S1C | 53.1 (15) |
C9—C8—C3 | 115.8 (3) | S1B—O1B—S1C | 41.5 (3) |
C7—C8—C3 | 105.4 (3) | S1C—C1B—S1B | 44.3 (7) |
O9—C9—C10 | 117.3 (4) | C1C—C2B—S1C | 89.2 (17) |
O9—C9—C8 | 119.3 (4) | C1C—C2B—S1B | 48.2 (15) |
C10—C9—C8 | 122.9 (4) | S1C—C2B—S1B | 41.0 (5) |
O10—C10—C11 | 111.9 (4) | S1B—S1C—C1B | 81.6 (14) |
O10—C10—C9 | 109.9 (4) | S1B—S1C—O1C | 77.1 (8) |
C11—C10—C9 | 113.2 (3) | C1B—S1C—O1C | 105.6 (13) |
C12—C11—C10 | 120.5 (4) | S1B—S1C—C2B | 81.1 (10) |
C12—C11—C15 | 120.0 (4) | C1B—S1C—C2B | 127.9 (12) |
C10—C11—C15 | 119.2 (4) | O1C—S1C—C2B | 117.6 (11) |
C11—C12—C18 | 125.5 (4) | S1B—S1C—C2C | 77.1 (14) |
C11—C12—C13 | 119.5 (4) | C1B—S1C—C2C | 10 (2) |
C18—C12—C13 | 114.9 (4) | O1C—S1C—C2C | 112.6 (15) |
O13—C13—C12 | 109.4 (4) | C2B—S1C—C2C | 118.0 (15) |
O13—C13—C14 | 109.7 (4) | S1B—S1C—O1B | 53.4 (4) |
C12—C13—C14 | 111.5 (4) | C1B—S1C—O1B | 105.0 (12) |
C1—C14—C13 | 118.1 (4) | O1C—S1C—O1B | 24.6 (7) |
C16—C15—C11 | 116.9 (4) | C2B—S1C—O1B | 103.0 (10) |
C16—C15—C17 | 105.2 (3) | C2C—S1C—O1B | 108.2 (13) |
C11—C15—C17 | 108.5 (4) | S1B—S1C—C1C | 47.7 (9) |
C16—C15—C1 | 109.7 (4) | C1B—S1C—C1C | 112.2 (15) |
C11—C15—C1 | 106.2 (4) | O1C—S1C—C1C | 102.9 (11) |
C17—C15—C1 | 110.2 (4) | C2B—S1C—C1C | 33.4 (9) |
O5—C20—C4 | 91.4 (3) | C2C—S1C—C1C | 103.1 (16) |
O21—C21—O2 | 124.3 (4) | O1B—S1C—C1C | 80.6 (9) |
O21—C21—C22 | 123.2 (4) | O1B—O1C—S1C | 102.3 (18) |
O2—C21—C22 | 112.5 (4) | O1B—O1C—S1B | 59.7 (14) |
C23—C22—C27 | 118.8 (5) | S1C—O1C—S1B | 44.1 (6) |
C23—C22—C21 | 123.0 (4) | C2B—C1C—S1B | 98 (2) |
C27—C22—C21 | 118.1 (5) | C2B—C1C—S1C | 57.5 (17) |
C24—C23—C22 | 119.8 (5) | S1B—C1C—S1C | 40.6 (7) |
C25—C24—C23 | 120.9 (6) | S1C—C2C—S1B | 40.2 (9) |
Hydrogen-bond geometry (Å, º) top
D—H···A | D—H | H···A | D···A | D—H···A |
O1—H1···O1B | 0.90 (1) | 1.98 (1) | 2.865 (10) | 166 (1) |
O1—H1···O1C | 0.90 (1) | 1.75 (2) | 2.631 (16) | 165 (1) |
O7—H7···O1A | 0.96 (1) | 1.73 (1) | 2.678 (8) | 169 (1) |
O13—H13···O9i | 0.99 (1) | 2.19 (1) | 3.128 (7) | 156 (1) |
O10—H10···O9 | 0.76 (1) | 2.10 (1) | 2.581 (5) | 122 (1) |
Symmetry code: (i) x−1, y, z. |
Experimental details
Crystal data |
Chemical formula | C29H36O10·2C2H6OS |
Mr | 700.83 |
Crystal system, space group | Monoclinic, P21 |
Temperature (K) | 293 |
a, b, c (Å) | 9.3677 (10), 21.991 (4), 9.4564 (11) |
β (°) | 115.827 (9) |
V (Å3) | 1753.5 (4) |
Z | 2 |
Radiation type | Mo Kα |
µ (mm−1) | 0.21 |
Crystal size (mm) | 0.5 × 0.4 × 0.3 |
|
Data collection |
Diffractometer | Bruker P4 diffractometer |
Absorption correction | – |
No. of measured, independent and observed [I > 2σ(I)] reflections | 4342, 4103, 3005 |
Rint | 0.025 |
(sin θ/λ)max (Å−1) | 0.649 |
|
Refinement |
R[F2 > 2σ(F2)], wR(F2), S | 0.056, 0.136, ? |
No. of reflections | 4100 |
No. of parameters | 436 |
No. of restraints | 1 |
H-atom treatment | H atoms treated by a mixture of independent and constrained refinement |
Δρmax, Δρmin (e Å−3) | 0.34, −0.26 |
Absolute structure | Flack (1983) |
Absolute structure parameter | 0.08 (15) |
Selected geometric parameters (Å, º) topC1—C14 | 1.539 (7) | C6—C7 | 1.515 (7) |
C1—C15 | 1.561 (6) | C7—C8 | 1.567 (7) |
C1—C2 | 1.566 (6) | C8—C9 | 1.551 (6) |
C2—C3 | 1.561 (6) | C9—C10 | 1.522 (7) |
C3—C4 | 1.551 (5) | C10—C11 | 1.509 (6) |
C3—C8 | 1.579 (5) | C11—C12 | 1.343 (7) |
C4—C20 | 1.529 (6) | C11—C15 | 1.530 (7) |
C5—O5 | 1.456 (6) | C12—C13 | 1.524 (7) |
C5—C6 | 1.523 (7) | C13—C14 | 1.548 (7) |
O5—C20 | 1.444 (6) | | |
| | | |
C14—C1—C15 | 111.1 (4) | C6—C7—C8 | 111.4 (4) |
C14—C1—C2 | 111.6 (4) | C9—C8—C7 | 102.2 (3) |
C15—C1—C2 | 111.3 (4) | C19—C8—C3 | 113.8 (3) |
C3—C2—C1 | 118.8 (3) | C9—C8—C3 | 115.8 (3) |
C4—C3—C2 | 111.7 (3) | C7—C8—C3 | 105.4 (3) |
C4—C3—C8 | 110.3 (3) | C10—C9—C8 | 122.9 (4) |
C2—C3—C8 | 116.0 (3) | C11—C10—C9 | 113.2 (3) |
C20—C4—C5 | 85.8 (3) | C12—C11—C10 | 120.5 (4) |
C20—C4—C3 | 120.4 (3) | C12—C11—C15 | 120.0 (4) |
C5—C4—C3 | 120.8 (3) | C10—C11—C15 | 119.2 (4) |
O5—C5—C6 | 113.7 (4) | C11—C12—C13 | 119.5 (4) |
O5—C5—C4 | 90.8 (4) | C12—C13—C14 | 111.5 (4) |
C6—C5—C4 | 119.2 (4) | C1—C14—C13 | 118.1 (4) |
C20—O5—C5 | 91.8 (3) | C11—C15—C1 | 106.2 (4) |
C7—C6—C5 | 113.5 (4) | O5—C20—C4 | 91.4 (3) |
Hydrogen-bond geometry (Å, º) top
D—H···A | D—H | H···A | D···A | D—H···A |
O1—H1···O1B | 0.900 (6) | 1.984 (10) | 2.865 (10) | 166.3 (6) |
O1—H1···O1C | 0.900 (6) | 1.754 (16) | 2.631 (16) | 164.8 (5) |
O7—H7···O1A | 0.958 (6) | 1.733 (8) | 2.678 (8) | 168.6 (5) |
O13—H13···O9i | 0.993 (8) | 2.194 (7) | 3.128 (7) | 156.1 (8) |
O10—H10···O9 | 0.755 (7) | 2.101 (5) | 2.581 (5) | 121.9 (5) |
Symmetry code: (i) x−1, y, z. |
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The success of paclitaxel and docetaxel (also known as taxol and taxotere, respectively) as anticancer drugs has prompted study of the crystal structures of these and related taxanes. These studies have revealed the structures of both paclitaxel (Mastropaolo et al., 1995) and docetaxel (Gueritte-Voegelein et al., 1990) as well as 2-carbamate taxol (Gao & Golik, 1995), baccatin V (Castellano & Hodder, 1973), 7-mesylpaclitaxel (Gao & Chen, 1996), baccatin III (Gabetta et al., 1995) and 10-deacetyl-7-epitaxol (Gao & Parker, 1996) which share a common tetracyclic ring structure and substitution pattern with paclitaxcel and docetaxel. However, no studies have yet appeared describing the crystal structure of 10-deacetyl baccatin III used in the semi-synthetic production of both paclitaxel and docetaxel. In addition baccatin III derivatives display unusual reactivity as a result of a congested tertiary structure. A description of the structure of 10-deacetyl baccatin III, (I), is therefore of interest. \sch
A crystal of 10-deacetyl baccatin III serendipitously appeared upon evaporation of a dimethyl sulfoxide (DMSO) solution under vacuum. The crystal was of sufficient quality to be subjected to X-ray analysis. The solid obtained contains two DMSO molecules acting as hydrogen-bond acceptors to the hydroxy H atoms at O1 and O7 (Figure 1). Hydrogen-bonding data are given in Table 2. Disorder is observed in the DMSO molecule which is hydrogen-bonded to O1 and consists primarily of inversion about the sulfur atom. Refinement of this DMSO found an approximately 2:1 occupancy of the B and C forms, respectively. This disorder is expected to cause a corresponding change in the H1—O1—C1—C2 dihedral angle due to H1 following the oxygen of DMSO from one form to another. This subtle change is not discernable in the position of the O1 atom and is not expected for the H1 as the present study would be insensitive to the motion of a hydrogen atom. However, previous work (Harper & Grant, 2000) suggests that the difference may be important in solid-state NMR analyses currently being pursued in our laboratory. The OH at position C13 serves as a hydrogen-bond donor to the C9 carbonyl in a neighboring molecule. The C9 carbonyl additionally forms a weak intramolecular hydrogen bond with the OH at C10. The carbonyl of the benzoyl moiety in an adjacent molecule and the S1A sulfur of the DMSO appear to interact via an intermolecular electrostatic dipole-dipole interaction [S1A···O21 = 3.265 (5) Å (2 - x, 1/2 + y, 1 - z), O1A—S1A···O21 = 170.3 (4)°]. This type of electrostatic interaction suggests an additional possible role for the benzoyl group in the bioactivity of taxanes.
The present analysis also identifies differences in 10-deacetyl baccatin III relative to the related compounds docetaxel and baccatin III. Docetaxel differs most significant from 10-deacetyl baccatin III in the relative orientation of the benzoyl's carboxyl and benzene groups. Deviations from co-planarity, as found in docetaxel, are likely to be costly in terms of π-electron delocalization. This study, in conjunction with the earlier studies on related derivatives, establishes that the benzoyl group exhibits an unexpected conformational flexibility that may be relevant to the bioactivity of taxanes.
The structure of 10-deacetyl baccatin III also differs from the most closely related analog, baccatin III, primarily in the cyclooctane and cyclohexane rings. Most significantly, eight corresponding dihedral angles differ by more than 7° [with three of these (C3—C2—C1—O1, C5—C6—C7—C8, and C7—C6—C5—O5) differing by nearly 10°]. Accompanying these differences are significantly shorter bond lengths at C6—C7 and C9—C10 of 10-deacetyl baccatin III. The observation of a shorter C9—C10 bond length in 10-deacetyl baccatin III (1.523 Å versus 1.580 Å in baccatin III) supports Gabetta's contention (Gabetta et al., 1995) that `···linear strain in baccatin III derivatives is affected by acylation···'.