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Acta Cryst. (2007). E63, o3372    [ doi:10.1107/S1600536807031376 ]

rac-N-(6a-Butyl-6-chloro-2-oxoperhydrofuro[3,2-b]furan-3-yl)-2,2,2-trifluoroacetamide

J. Erdsack, M. Schürmann, H. Preut and N. Krause

Abstract top

The title compound, C12H15ClF3NO4, is a side product in a synthesis of novel furanomycin derivatives. The stereochemistry at the bicyclic core is consistent with a halolactonization step. However, racemization also occurred via an unknown mechanism. The five-membered rings are nearly perpendicular to each other [torsion angle at the common bond: -95.6 (2)°].

Comment top

The title compound, (I),is a side product in the preparation of novel furanomycin derivatives using the gold-catalyzed cyclization of α-hydroxyallenes (Hoffmann-Röder & Krause, 2001; Erdsack & Krause, 2007) (Fig. 1). The torsion angle O3—C3a—C6a—O1 is −95.6 (2)°. Although the synthesis started from enantiomerically pure L-serine, compound (I) crystallizes in a achiral space group (P1): in the arbitrarily chosen asymmetric molecule, the configurations of the stereogenic centres are C3 R, C3A S, C6 R, and C6A R. This raecemization is in contrast to a related compound (Erdsack, Schürmann et al., 2007).

Related literature top

For related literature, see: Erdsack & Krause (2007); Erdsack et al. (2007); Hoffmann-Röder & Krause (2001).

Experimental top

A small amount of the title compound which arose as a side product in the gold-catalyzed cyclization of α-hydroxyallenes (Erdsack & Krause, 2007) was suspended in a few drops of iso-hexane. Ethyl acetate was added dropwise until the compound was complete dissolved, and colourless blocks of (I) were obtained by slow evaporation at ambient temperature.

Refinement top

The H atoms were placed in calculated positions, with C—H = 0.96–0.98 and N—H = 0.86 Å and refined as riding, with Uiso= 1.5Ueq; the methyl groups were allowed to rotate but not to tip. The –CF3 fluorine atoms are disordered over two positions of equal occupancy.

Computing details top

Data collection: COLLECT (Nonius, 1998); cell refinement: DENZO and SCALEPACK (Otwinowski & Minor, 1997); data reduction: DENZO and SCALEPACK; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL-Plus (Sheldrick, 1991); software used to prepare material for publication: SHELXTL and PLATON (Spek, 2003).

Figures top
[Figure 1] Fig. 1. : The molecular structure of (I) with displacement ellipsoids shown at the 20% probability level (arbitrary spheres for the H atoms). The F atoms are disordered over two positions; only one is shown.
rac-N-(6a-Butyl-6-chloro-2-oxoperhydrofuro[3,2-b]furan-3-yl)-2,2,2- trifluoroacetamide top
Crystal data top
C12H15ClF3NO4Z = 2
Mr = 329.70F(000) = 340
Triclinic, P1Dx = 1.482 Mg m−3
Hall symbol: -P 1Mo Kα radiation, λ = 0.71073 Å
a = 7.674 (3) ÅCell parameters from 8179 reflections
b = 9.586 (3) Åθ = 3.1–25.3°
c = 11.590 (4) ŵ = 0.31 mm−1
α = 66.904 (13)°T = 291 K
β = 76.782 (14)°Block, colourless
γ = 71.684 (13)°0.10 × 0.08 × 0.08 mm
V = 739.1 (4) Å3
Data collection top
Nonius KappaCCD area-detector
diffractometer		959 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tubeRint = 0.031
graphiteθmax = 25.3°, θmin = 3.1°
Detector resolution: 19 vertical, 18 horizontal pixels mm-1h = −9→9
185 frames via ω–rotation (Δω = 2°) and two times 190 s per frame (four sets at different κ–angles) scansk = −10→11
8179 measured reflectionsl = −13→13
2680 independent reflections
Refinement top
Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: fullHydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.031H-atom parameters constrained
wR(F2) = 0.079 w = [1.0 exp(4.90(sinθ/λ)2)]/[σ2(Fo2)]
S = 0.91(Δ/σ)max < 0.001
2680 reflectionsΔρmax = 0.14 e Å−3
219 parametersΔρmin = −0.12 e Å−3
0 restraintsExtinction correction: SHELXL97, Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
Primary atom site location: structure-invariant direct methodsExtinction coefficient: 0.0297 (18)
Crystal data top
C12H15ClF3NO4γ = 71.684 (13)°
Mr = 329.70V = 739.1 (4) Å3
Triclinic, P1Z = 2
a = 7.674 (3) ÅMo Kα radiation
b = 9.586 (3) ŵ = 0.31 mm−1
c = 11.590 (4) ÅT = 291 K
α = 66.904 (13)°0.10 × 0.08 × 0.08 mm
β = 76.782 (14)°
Data collection top
Nonius KappaCCD area-detector
diffractometer		959 reflections with I > 2σ(I)
8179 measured reflectionsRint = 0.031
2680 independent reflectionsθmax = 25.3°
Refinement top
R[F2 > 2σ(F2)] = 0.031H-atom parameters constrained
wR(F2) = 0.079Δρmax = 0.14 e Å−3
S = 0.91Δρmin = −0.12 e Å−3
2680 reflectionsAbsolute structure: ?
219 parametersFlack parameter: ?
0 restraintsRogers parameter: ?
Special details top

Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes.

Refinement. Refinement of F2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F2, conventional R-factors R are based on F, with F set to zero for negative F2. The threshold expression of F2 > σ(F2) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F2 are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/UeqOcc. (<1)
Cl0.33628 (12)0.95641 (10)0.80355 (9)0.0743 (3)
O10.8738 (3)0.7457 (2)0.79610 (18)0.0569 (6)
C20.9876 (5)0.7001 (4)0.8845 (3)0.0513 (8)
O21.1278 (3)0.5984 (2)0.88767 (19)0.0630 (6)
C30.9078 (4)0.7944 (3)0.9721 (3)0.0465 (8)
H30.97230.87740.94640.070*
C3A0.7091 (4)0.8701 (3)0.9452 (3)0.0500 (8)
H3A0.66880.97650.94800.075*
O30.5884 (3)0.7760 (2)1.02971 (18)0.0617 (6)
C50.5403 (5)0.6972 (4)0.9643 (3)0.0677 (10)
H5A0.41790.67990.99760.102*
H5B0.62840.59680.97270.102*
C60.5449 (4)0.8043 (3)0.8274 (3)0.0577 (9)
H60.56700.74550.77050.087*
C6A0.7094 (4)0.8714 (3)0.8124 (3)0.0494 (8)
C70.7242 (4)1.0219 (3)0.7034 (3)0.0583 (9)
H7A0.83771.04620.70330.087*
H7B0.62201.10640.71700.087*
C80.7227 (5)1.0161 (4)0.5739 (3)0.0705 (10)
H8A0.60930.99180.57360.106*
H8B0.82540.93220.55960.106*
C90.7371 (6)1.1697 (5)0.4656 (3)0.0884 (12)
H9A0.84331.19970.47160.133*
H9B0.75841.15220.38600.133*
C100.5713 (7)1.3005 (5)0.4645 (4)0.1211 (17)
H10A0.46301.26680.47090.182*
H10B0.58051.38700.38710.182*
H10C0.56271.33250.53480.182*
N0.9323 (3)0.6989 (3)1.1019 (2)0.0534 (7)
H00.88770.61801.13630.080*
C111.0213 (4)0.7313 (4)1.1703 (3)0.0548 (8)
O41.0949 (3)0.8376 (3)1.13432 (19)0.0769 (8)
C121.0293 (8)0.6182 (6)1.3066 (4)0.0761 (12)
F1A1.019 (3)0.691 (2)1.3743 (14)0.142 (8)0.50
F2A0.896 (3)0.543 (2)1.347 (2)0.131 (8)0.50
F3A1.189 (3)0.5103 (18)1.3085 (15)0.152 (6)0.50
F1B0.950 (3)0.6885 (19)1.3945 (14)0.125 (6)0.50
F2B0.950 (3)0.509 (2)1.3365 (19)0.120 (7)0.50
F3B1.1950 (19)0.557 (2)1.3374 (14)0.151 (7)0.50
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Cl0.0550 (6)0.0754 (7)0.0948 (7)−0.0065 (5)−0.0206 (5)−0.0334 (5)
O10.0550 (15)0.0568 (14)0.0650 (15)−0.0057 (12)−0.0121 (12)−0.0312 (11)
C20.051 (2)0.044 (2)0.058 (2)−0.0196 (19)−0.0050 (19)−0.0110 (18)
O20.0540 (16)0.0506 (14)0.0762 (16)−0.0040 (13)−0.0103 (13)−0.0193 (12)
C30.050 (2)0.0396 (18)0.051 (2)−0.0147 (17)−0.0094 (16)−0.0127 (16)
C3A0.056 (2)0.0449 (18)0.053 (2)−0.0140 (18)−0.0075 (17)−0.0184 (15)
O30.0581 (16)0.0673 (15)0.0614 (14)−0.0248 (13)−0.0031 (11)−0.0194 (12)
C50.062 (3)0.058 (2)0.087 (3)−0.019 (2)−0.014 (2)−0.024 (2)
C60.048 (2)0.053 (2)0.080 (3)−0.0040 (18)−0.0157 (18)−0.0339 (19)
C6A0.046 (2)0.0496 (19)0.061 (2)−0.0094 (17)−0.0120 (16)−0.0271 (17)
C70.067 (2)0.053 (2)0.058 (2)−0.0166 (19)−0.0177 (17)−0.0156 (17)
C80.080 (3)0.077 (3)0.057 (2)−0.014 (2)−0.0190 (19)−0.025 (2)
C90.104 (4)0.095 (3)0.060 (2)−0.033 (3)−0.016 (2)−0.011 (2)
C100.142 (5)0.083 (3)0.115 (4)−0.011 (3)−0.049 (3)−0.006 (3)
N0.0655 (19)0.0454 (16)0.0494 (16)−0.0208 (15)−0.0139 (14)−0.0074 (13)
C110.057 (2)0.051 (2)0.053 (2)−0.0059 (18)−0.0176 (17)−0.0144 (17)
O40.097 (2)0.0751 (17)0.0720 (16)−0.0455 (16)−0.0281 (13)−0.0117 (13)
C120.098 (5)0.073 (3)0.060 (3)−0.028 (3)−0.024 (3)−0.013 (3)
F1A0.28 (2)0.159 (10)0.036 (5)−0.148 (12)−0.003 (8)−0.023 (5)
F2A0.148 (9)0.171 (17)0.076 (6)−0.108 (11)−0.011 (5)0.009 (9)
F3A0.196 (13)0.097 (6)0.126 (9)0.036 (6)−0.103 (8)−0.010 (5)
F1B0.195 (11)0.099 (7)0.061 (6)−0.032 (8)0.015 (6)−0.027 (5)
F2B0.24 (2)0.065 (4)0.066 (7)−0.070 (8)−0.052 (10)0.011 (4)
F3B0.084 (7)0.213 (16)0.097 (7)−0.010 (8)−0.047 (5)0.006 (8)
Geometric parameters (Å, °) top
Cl—C61.784 (3)C8—H8A0.9700
O1—C21.350 (3)C8—H8B0.9700
O1—C6A1.481 (3)C9—C101.477 (5)
C2—O21.200 (3)C9—H9A0.9700
C2—C31.521 (4)C9—H9B0.9700
C3—N1.441 (3)C10—H10A0.9600
C3—C3A1.514 (4)C10—H10B0.9600
C3—H30.9800C10—H10C0.9600
C3A—O31.431 (3)N—C111.329 (3)
C3A—C6A1.534 (4)N—H00.8600
C3A—H3A0.9800C11—O41.205 (3)
O3—C51.425 (3)C11—C121.528 (5)
C5—C61.515 (4)C12—F1A1.213 (16)
C5—H5A0.9700C12—F2B1.269 (16)
C5—H5B0.9700C12—F3B1.290 (15)
C6—C6A1.537 (4)C12—F3A1.328 (18)
C6—H60.9800C12—F2A1.332 (18)
C6A—C71.516 (4)C12—F1B1.364 (16)
C7—C81.526 (4)F1A—F1B0.53 (4)
C7—H7A0.9700F1A—F3B1.65 (3)
C7—H7B0.9700F3A—F3B0.67 (3)
C8—C91.532 (4)
C2—O1—C6A111.6 (2)C10—C9—C8113.9 (3)
O2—C2—O1121.7 (3)C10—C9—H9A108.8
O2—C2—C3128.7 (3)C8—C9—H9A108.8
O1—C2—C3109.6 (3)C10—C9—H9B108.8
N—C3—C3A115.4 (2)C8—C9—H9B108.8
N—C3—C2111.9 (3)H9A—C9—H9B107.7
C3A—C3—C2104.3 (2)C9—C10—H10A109.5
N—C3—H3108.3C9—C10—H10B109.5
C3A—C3—H3108.3H10A—C10—H10B109.5
C2—C3—H3108.3C9—C10—H10C109.5
O3—C3A—C3111.3 (2)H10A—C10—H10C109.5
O3—C3A—C6A107.2 (2)H10B—C10—H10C109.5
C3—C3A—C6A104.3 (2)C11—N—C3122.4 (2)
O3—C3A—H3A111.2C11—N—H0118.8
C3—C3A—H3A111.2C3—N—H0118.8
C6A—C3A—H3A111.2O4—C11—N126.4 (3)
C5—O3—C3A108.9 (2)O4—C11—C12119.1 (3)
O3—C5—C6105.6 (2)N—C11—C12114.5 (3)
O3—C5—H5A110.6F1A—C12—F2B123.9 (13)
C6—C5—H5A110.6F1A—C12—F3B82.6 (12)
O3—C5—H5B110.6F2B—C12—F3B108.5 (13)
C6—C5—H5B110.6F1A—C12—F3A111.9 (13)
H5A—C5—H5B108.8F2B—C12—F3A87.0 (13)
C5—C6—C6A101.5 (2)F3B—C12—F3A29.8 (12)
C5—C6—Cl110.3 (2)F1A—C12—F2A110.0 (14)
C6A—C6—Cl110.6 (2)F2B—C12—F2A20.3 (18)
C5—C6—H6111.3F3B—C12—F2A124.4 (14)
C6A—C6—H6111.3F3A—C12—F2A106.7 (12)
Cl—C6—H6111.3F1A—C12—F1B22.8 (16)
O1—C6A—C7108.3 (2)F2B—C12—F1B104.4 (13)
O1—C6A—C3A104.4 (2)F3B—C12—F1B100.4 (11)
C7—C6A—C3A116.8 (2)F3A—C12—F1B126.9 (11)
O1—C6A—C6104.2 (2)F2A—C12—F1B88.2 (13)
C7—C6A—C6118.1 (3)F1A—C12—C11108.9 (9)
C3A—C6A—C6103.5 (2)F2B—C12—C11115.1 (10)
C6A—C7—C8114.2 (2)F3B—C12—C11113.4 (7)
C6A—C7—H7A108.7F3A—C12—C11106.8 (9)
C8—C7—H7A108.7F2A—C12—C11112.6 (11)
C6A—C7—H7B108.7F1B—C12—C11113.8 (8)
C8—C7—H7B108.7F1B—F1A—C1295 (3)
H7A—C7—H7B107.6F1B—F1A—F3B131 (4)
C7—C8—C9113.2 (3)C12—F1A—F3B50.7 (9)
C7—C8—H8A108.9F3B—F3A—C1272 (3)
C9—C8—H8A108.9F1A—F1B—C1262 (3)
C7—C8—H8B108.9F3A—F3B—C1278 (3)
C9—C8—H8B108.9F3A—F3B—F1A124 (3)
H8A—C8—H8B107.8C12—F3B—F1A46.7 (8)
C6A—O1—C2—O2179.4 (2)O4—C11—C12—F3B−53.6 (12)
C6A—O1—C2—C3−0.1 (3)N—C11—C12—F3B125.6 (10)
O2—C2—C3—N−39.3 (4)O4—C11—C12—F3A−84.7 (9)
O1—C2—C3—N140.1 (2)N—C11—C12—F3A94.6 (9)
O2—C2—C3—C3A−164.7 (3)O4—C11—C12—F2A158.6 (11)
O1—C2—C3—C3A14.7 (3)N—C11—C12—F2A−22.1 (12)
N—C3—C3A—O3−30.3 (3)O4—C11—C12—F1B60.2 (11)
C2—C3—C3A—O392.8 (2)N—C11—C12—F1B−120.5 (10)
N—C3—C3A—C6A−145.6 (2)F2B—C12—F1A—F1B−34 (5)
C2—C3—C3A—C6A−22.5 (3)F3B—C12—F1A—F1B−141 (4)
C3—C3A—O3—C5−103.4 (3)F3A—C12—F1A—F1B−136 (4)
C6A—C3A—O3—C510.1 (3)F2A—C12—F1A—F1B−17 (4)
C3A—O3—C5—C6−30.0 (3)C11—C12—F1A—F1B107 (4)
O3—C5—C6—C6A36.8 (3)F2B—C12—F1A—F3B107.3 (16)
O3—C5—C6—Cl−80.5 (2)F3A—C12—F1A—F3B5.6 (15)
C2—O1—C6A—C7110.7 (2)F2A—C12—F1A—F3B124.0 (14)
C2—O1—C6A—C3A−14.4 (3)F1B—C12—F1A—F3B141 (4)
C2—O1—C6A—C6−122.7 (2)C11—C12—F1A—F3B−112.2 (9)
O3—C3A—C6A—O1−95.6 (2)F1A—C12—F3A—F3B−11 (3)
C3—C3A—C6A—O122.6 (2)F2B—C12—F3A—F3B−137 (3)
O3—C3A—C6A—C7144.8 (3)F2A—C12—F3A—F3B−132 (3)
C3—C3A—C6A—C7−97.0 (3)F1B—C12—F3A—F3B−31 (3)
O3—C3A—C6A—C613.2 (3)C11—C12—F3A—F3B108 (2)
C3—C3A—C6A—C6131.4 (2)F3B—F1A—F1B—C12−40 (3)
C5—C6—C6A—O179.4 (3)F2B—C12—F1B—F1A151 (4)
Cl—C6—C6A—O1−163.56 (18)F3B—C12—F1B—F1A39 (4)
C5—C6—C6A—C7−160.4 (3)F3A—C12—F1B—F1A54 (4)
Cl—C6—C6A—C7−43.4 (3)F2A—C12—F1B—F1A164 (4)
C5—C6—C6A—C3A−29.6 (3)C11—C12—F1B—F1A−82 (4)
Cl—C6—C6A—C3A87.5 (3)C12—F3A—F3B—F1A9(2)
O1—C6A—C7—C862.9 (3)F1A—C12—F3B—F3A170 (3)
C3A—C6A—C7—C8−179.7 (3)F2B—C12—F3B—F3A46 (3)
C6—C6A—C7—C8−55.2 (4)F2A—C12—F3B—F3A60 (3)
C6A—C7—C8—C9179.8 (3)F1B—C12—F3B—F3A155 (3)
C7—C8—C9—C10−69.0 (4)C11—C12—F3B—F3A−83 (3)
C3A—C3—N—C11−118.5 (3)F2B—C12—F3B—F1A−123.4 (13)
C2—C3—N—C11122.5 (3)F3A—C12—F3B—F1A−170 (3)
C3—N—C11—O4−2.0 (5)F2A—C12—F3B—F1A−109.2 (16)
C3—N—C11—C12178.8 (4)F1B—C12—F3B—F1A−14.3 (14)
O4—C11—C12—F1A36.3 (13)C11—C12—F3B—F1A107.4 (11)
N—C11—C12—F1A−144.4 (12)F1B—F1A—F3B—F3A43 (6)
O4—C11—C12—F2B−179.4 (12)C12—F1A—F3B—F3A−12 (3)
N—C11—C12—F2B−0.1 (13)F1B—F1A—F3B—C1256 (5)
references
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