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Acta Cryst. (2007). E63, o3371    [ doi:10.1107/S1600536807031388 ]

(3R,3aS,6R,6aR)-tert-Butyl N-(6-chloro-2-oxo-6a-phenylperhydrofuro[3,2-b]furan-3-yl)carbamate

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

Abstract top

The chiral title compound, C17H20ClNO5, arose as a side product during the synthesis of novel furanomycin derivatives. The stereochemistry at the bicyclic core is consistent with a halolactonization step. The five-membered rings are nearly perpendicular to each other [torsion angle at the common bond: -88.3 (3)°].

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). It was obtained after an aldehyde oxidation in the presence of NaClO2 and chlorolactonization of the resulted boc-protected amino acid intermediate by hypochloric acid, a degradation product of the oxidant (Erdsack & Krause, 2007). A crystal structure determination of (I) has now been carried out to establish the relative configuration of the stereogenic centers at the bicyclic core. Fig. 1 shows that the relative configuration of C6 and C6a is consistent with the stereospecific halolactonization step. The torsion angle O3—C7—C10—O1 is −88.3 (3)°. The configurations of the stereogenic C atoms in (I) (C3 R, C3a S, C6 R and C6a R) were established by refining the Flack (1983) absolute structure parameter; they are consistent with those of the equivalent atoms in the starting material (Erdsack et al., 2007).

Related literature top

For related literature, see: Erdsack & Krause (2007); Erdsack et al. (2007); Flack (1983); Hoffmann-Röder & Krause (2001).

Experimental top

In a Schlenk tube equipped with a magnetic stirrer bar, 47 mg (0.15 mmol) of tert-butyl-(1R,2S)-[2-hydroxy-1-(3-phenyl-2,5-dihydrofuran-2-yl)-ethyl]-carbamate (synthesis of this compound will be described elsewhere; Erdsack & Krause 2007) was dissolved in dry dichloromethane (1.5 ml) under argon and cooled to 273 K. With stirring, 87 mg (0.23 mmol) of Dess-Martin periodinane was added in one portion. After 2 h, the mixture was diluted with diethyl ether (3 ml), quenched with sat. aq. NaHCO3 and sat. aq. Na2S2O3 1:1 (5 ml) and diluted with additional 3 ml of diethyl ether. After a few minutes with stirring at r.t., the biphasic mixture came clear. The organic phase was separated and the residue was extracted with diethyl ether (3 × 10 ml). The combined organic layers were washed with aq. sat. NaHCO3 and brine and dried with MgSO4. The solution was filtered and the solvent was evaporated. The crude aldehyde was dissolved in a 1:1 mixture of t-BuOH/THF (5 ml). The flask was sealed with a rubber septum and was cooled to 273 K. With vigorous stirring, a solution of NaClO2 (80%, technical grade, 52 mg, 0.46 mmol) and NaH2PO4*H2O (82 mg, 0.46 mmol) in 1 ml water was slowly added dropwise via syringe over 30 min. The reaction mixture came yellow and was allowed to stir at r.t. overnight. The mixture was diluted with water (15 ml) and extracted with diethyl ether (3 × 15 ml). The combined organic layers were dried (MgSO4), filtered and the solvent was evaporated. The residue was purified by column chromatography on silica gel (iso-hexane/EtOAc 4:1 v/v) to give 28 mg (53%) of the lactone (I) as a solid, which was suspended in a few drops of iso-hexane. Ethyl acetate was added dropwise until the compound was completely dissolved, and colourless needles of (I) were obtained by slow evaporation at ambient temperature; mp 432 K; [α]D21 − 44.0 (c 1.40, CHCl3); IR (KBr pellet), cm−1: 3419 (m), 3323 (m), 3062 (w), 2979 (m), 2932 (m), 2885 (w), 1801 (s), 1712 (s), 1510 (m), 1451 (m), 1393 (m), 1368 (m), 1253 (m), 1163 (s), 1104 (m), 1062 (m), 942 (s), 865 (m), 751 (m), 734 (m), 699 (m), 665 (w), 577 (w), 514 (w); 1H NMR (400 MHz, CDCl3): δ (p.p.m.): 7.48 − 7.43 (m, 5 H), 5.22 (dd, J = 6.3, 13.6 Hz, 1 H), 4.69 (dd, J = 4.0, 8.6 Hz, 1 H), 4.62 (d, J = 3.4 Hz, 1 H), 4.51 (dd, J = 3.9, 10.5 Hz, 1 H), 4.32 (d, J = 10.5 Hz, 1 H), 1.46 (m, 9 H); 13C NMR (100.6 MHz, CDCl3): δ (p.p.m.) 172.0, 155.2, 132.1, 129.8, 128.7, 127.0, 94.8, 81.0, 80.1, 76.9, 63.3, 54.1, 28.2 HRMS (ESI): m/z calculated for C17H21O5N35Cl: [M + H]+ = 354.11028, found 354.11002

Refinement top

The H atoms were placed in calculated positions, with C—H = 0.93–0.98 and N—H = 0.86 Å and were refined as riding, with Uiso(H) = 1.5Ueq; the methyl groups were allowed to rotate but not to tip.

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: SHELXL97 and PLATON (Spek, 2003).

Figures top
[Figure 1] Fig. 1. : The molecular structure of (I) with displacement ellipsoids shown at the 30% probability level (arbitrary spheres for the H atoms).
(3R,3aS,6R,6aR)-tert-Butyl N-(6-chloro-2-oxo-6a-phenylperhydrofuro[3,2-b]furan-3-yl)carbamate top
Crystal data top
C17H20ClNO5F(000) = 744
Mr = 353.79Dx = 1.342 Mg m−3
Orthorhombic, P212121Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2ac 2abCell parameters from 14042 reflections
a = 6.1519 (7) Åθ = 3.1–25.8°
b = 12.029 (2) ŵ = 0.24 mm−1
c = 23.655 (4) ÅT = 291 K
V = 1750.5 (5) Å3Needle, colourless
Z = 40.44 × 0.08 × 0.08 mm
Data collection top
Nonius KappaCCD
diffractometer		1085 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tubeRint = 0.036
graphiteθmax = 25.8°, θmin = 3.1°
Detector resolution: 19 vertical, 18 horizontal pixels mm-1h = −7→7
309 frames via ω–rotation (Δω=1%) and two times 120 s per frame (three sets at different κ–angles) scansk = 0→14
14042 measured reflectionsl = 0→28
3280 independent reflections
Refinement top
Refinement on F2Hydrogen site location: inferred from neighbouring sites
Least-squares matrix: fullH-atom parameters constrained
R[F2 > 2σ(F2)] = 0.029 [1.0exp(7.10(sinθ/λ)2)]/[σ2(Fo2)]
wR(F2) = 0.079(Δ/σ)max < 0.001
S = 1.01Δρmax = 0.10 e Å−3
3280 reflectionsΔρmin = −0.11 e Å−3
221 parametersExtinction correction: SHELXL97, Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
0 restraintsExtinction coefficient: 0.0215 (9)
Primary atom site location: structure-invariant direct methodsAbsolute structure: Flack (1983), 1313 Friedel pairs
Secondary atom site location: difference Fourier mapFlack parameter: 0.08 (10)
Crystal data top
C17H20ClNO5V = 1750.5 (5) Å3
Mr = 353.79Z = 4
Orthorhombic, P212121Mo Kα radiation
a = 6.1519 (7) ŵ = 0.24 mm−1
b = 12.029 (2) ÅT = 291 K
c = 23.655 (4) Å0.44 × 0.08 × 0.08 mm
Data collection top
Nonius KappaCCD
diffractometer		1085 reflections with I > 2σ(I)
14042 measured reflectionsRint = 0.036
3280 independent reflectionsθmax = 25.8°
Refinement top
R[F2 > 2σ(F2)] = 0.029H-atom parameters constrained
wR(F2) = 0.079Δρmax = 0.10 e Å−3
S = 1.01Δρmin = −0.11 e Å−3
3280 reflectionsAbsolute structure: Flack (1983), 1313 Friedel pairs
221 parametersFlack parameter: 0.08 (10)
0 restraints
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*/Ueq
Cl0.6643 (2)0.59959 (10)0.85442 (5)0.1028 (4)
O10.5371 (4)0.6930 (2)0.97543 (10)0.0741 (7)
O20.0232 (4)0.5437 (2)1.04297 (11)0.0772 (8)
O30.1997 (4)0.5179 (2)0.96171 (11)0.0702 (7)
O40.5678 (5)0.4974 (2)1.14730 (11)0.0925 (9)
O50.5498 (4)0.6773 (2)1.17002 (11)0.0832 (8)
N0.4380 (4)0.6243 (2)1.08588 (12)0.0678 (8)
H00.39380.69171.08220.102*
C10.4893 (6)0.4053 (3)0.92572 (15)0.0687 (10)
C20.3421 (8)0.3404 (4)0.89794 (16)0.0938 (14)
H20.20480.36810.88940.141*
C30.3975 (9)0.2339 (4)0.88258 (19)0.1040 (17)
H30.29770.18970.86350.156*
C40.5945 (10)0.1938 (4)0.8950 (2)0.1002 (16)
H40.63140.12190.88430.150*
C50.7399 (9)0.2570 (4)0.9230 (2)0.1152 (18)
H50.87610.22810.93170.173*
C60.6885 (8)0.3633 (4)0.93866 (18)0.0982 (14)
H60.78910.40660.95810.147*
C70.4274 (6)0.5205 (3)0.94081 (14)0.0601 (10)
C80.4180 (6)0.6041 (3)0.89390 (14)0.0701 (10)
H80.29050.59280.86970.105*
C90.4034 (6)0.7103 (3)0.92654 (15)0.0781 (12)
H9A0.45700.77210.90420.117*
H9B0.25430.72540.93750.117*
C100.5502 (5)0.5787 (3)0.98781 (15)0.0626 (10)
H100.70110.55300.99060.094*
C110.4212 (5)0.5507 (3)1.03969 (15)0.0649 (10)
H110.46840.47721.05270.097*
C120.1912 (7)0.5391 (3)1.01752 (18)0.0662 (10)
C130.5233 (6)0.5907 (4)1.13647 (18)0.0727 (11)
C140.6347 (7)0.6647 (4)1.22849 (16)0.0861 (13)
C150.8603 (6)0.6207 (5)1.22662 (17)0.132 (2)
H15A0.92230.62301.26380.199*
H15B0.94620.66531.20150.199*
H15C0.85810.54531.21330.199*
C160.6267 (10)0.7804 (4)1.24998 (17)0.156 (3)
H16A0.48210.80911.24580.234*
H16B0.72630.82571.22890.234*
H16C0.66670.78131.28920.234*
C170.4855 (7)0.5924 (4)1.26134 (17)0.1118 (15)
H17A0.34080.62211.25960.168*
H17B0.53250.58961.30000.168*
H17C0.48660.51881.24560.168*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Cl0.1244 (9)0.0872 (8)0.0967 (8)0.0053 (8)0.0295 (7)0.0076 (7)
O10.0901 (18)0.0578 (18)0.0744 (18)−0.0033 (16)−0.0172 (15)0.0027 (13)
O20.0676 (17)0.0769 (19)0.0872 (19)0.0014 (16)−0.0038 (15)0.0033 (15)
O30.0584 (16)0.0840 (19)0.0682 (17)0.0018 (16)−0.0079 (14)−0.0048 (14)
O40.126 (2)0.0707 (19)0.0810 (19)0.0217 (19)−0.0200 (18)0.0004 (17)
O50.112 (2)0.0692 (19)0.0681 (17)−0.0006 (18)−0.0191 (16)0.0014 (15)
N0.080 (2)0.059 (2)0.0639 (19)0.0043 (18)−0.0168 (17)0.0010 (17)
C10.069 (3)0.065 (3)0.073 (3)0.001 (3)−0.002 (2)0.000 (2)
C20.107 (4)0.085 (3)0.089 (3)0.003 (3)−0.019 (3)−0.018 (3)
C30.130 (5)0.085 (4)0.096 (3)−0.016 (3)−0.008 (3)−0.017 (3)
C40.143 (5)0.059 (3)0.099 (4)0.003 (4)0.015 (4)0.003 (3)
C50.111 (5)0.071 (4)0.163 (5)0.015 (3)−0.013 (4)0.013 (4)
C60.093 (3)0.058 (3)0.144 (4)0.007 (3)−0.016 (3)−0.009 (3)
C70.054 (2)0.056 (3)0.070 (3)0.003 (2)−0.004 (2)−0.001 (2)
C80.074 (2)0.069 (3)0.067 (2)0.007 (3)−0.004 (2)0.004 (2)
C90.091 (3)0.068 (3)0.076 (3)0.006 (2)−0.016 (3)0.004 (2)
C100.059 (2)0.058 (3)0.070 (2)0.000 (2)−0.004 (2)−0.001 (2)
C110.064 (2)0.061 (3)0.070 (2)−0.002 (2)−0.016 (2)−0.006 (2)
C120.062 (3)0.057 (3)0.079 (3)0.000 (2)−0.008 (3)0.000 (2)
C130.068 (3)0.075 (3)0.075 (3)0.001 (3)−0.001 (2)−0.002 (3)
C140.107 (4)0.099 (4)0.053 (3)−0.004 (3)−0.018 (3)0.010 (2)
C150.085 (3)0.220 (6)0.092 (3)0.000 (4)−0.021 (3)0.021 (4)
C160.279 (8)0.100 (4)0.088 (4)−0.015 (5)−0.055 (5)−0.023 (3)
C170.112 (3)0.146 (4)0.078 (3)0.005 (4)0.009 (3)0.010 (3)
Geometric parameters (Å, °) top
Cl—C81.781 (3)C6—H60.9300
O1—C101.409 (4)C7—C81.499 (4)
O1—C91.434 (4)C7—C101.516 (4)
O2—C121.197 (4)C8—C91.496 (5)
O3—C121.346 (4)C8—H80.9800
O3—C71.486 (4)C9—H9A0.9700
O4—C131.183 (4)C9—H9B0.9700
O5—C131.320 (4)C10—C111.500 (4)
O5—C141.486 (4)C10—H100.9800
N—C131.368 (4)C11—C121.516 (5)
N—C111.410 (4)C11—H110.9800
N—H00.8600C14—C161.483 (5)
C1—C61.360 (5)C14—C171.484 (5)
C1—C21.364 (5)C14—C151.486 (5)
C1—C71.481 (5)C15—H15A0.9600
C2—C31.374 (6)C15—H15B0.9600
C2—H20.9300C15—H15C0.9600
C3—C41.337 (6)C16—H16A0.9600
C3—H30.9300C16—H16B0.9600
C4—C51.347 (6)C16—H16C0.9600
C4—H40.9300C17—H17A0.9600
C5—C61.369 (5)C17—H17B0.9600
C5—H50.9300C17—H17C0.9600
C10—O1—C9110.0 (3)O1—C10—C11111.0 (3)
C12—O3—C7111.0 (3)O1—C10—C7105.6 (3)
C13—O5—C14121.5 (3)C11—C10—C7103.5 (3)
C13—N—C11121.4 (3)O1—C10—H10112.1
C13—N—H0119.3C11—C10—H10112.1
C11—N—H0119.3C7—C10—H10112.1
C6—C1—C2119.6 (4)N—C11—C10117.0 (3)
C6—C1—C7121.6 (4)N—C11—C12113.2 (3)
C2—C1—C7118.7 (4)C10—C11—C12103.4 (3)
C1—C2—C3119.7 (5)N—C11—H11107.6
C1—C2—H2120.1C10—C11—H11107.6
C3—C2—H2120.1C12—C11—H11107.6
C4—C3—C2120.2 (5)O2—C12—O3122.4 (3)
C4—C3—H3119.9O2—C12—C11128.9 (4)
C2—C3—H3119.9O3—C12—C11108.7 (4)
C3—C4—C5120.4 (5)O4—C13—O5126.2 (4)
C3—C4—H4119.8O4—C13—N123.9 (4)
C5—C4—H4119.8O5—C13—N109.9 (4)
C4—C5—C6120.4 (5)C16—C14—C17110.5 (4)
C4—C5—H5119.8C16—C14—O5102.2 (3)
C6—C5—H5119.8C17—C14—O5109.3 (3)
C1—C6—C5119.6 (5)C16—C14—C15112.0 (4)
C1—C6—H6120.2C17—C14—C15112.6 (4)
C5—C6—H6120.2O5—C14—C15109.7 (3)
C1—C7—O3107.6 (3)C14—C15—H15A109.5
C1—C7—C8117.4 (3)C14—C15—H15B109.5
O3—C7—C8102.9 (3)H15A—C15—H15B109.5
C1—C7—C10118.7 (3)C14—C15—H15C109.5
O3—C7—C10103.6 (3)H15A—C15—H15C109.5
C8—C7—C10104.6 (3)H15B—C15—H15C109.5
C7—C8—C9101.1 (3)C14—C16—H16A109.5
C7—C8—Cl109.6 (3)C14—C16—H16B109.5
C9—C8—Cl110.3 (3)H16A—C16—H16B109.5
C7—C8—H8111.8C14—C16—H16C109.5
C9—C8—H8111.8H16A—C16—H16C109.5
Cl—C8—H8111.8H16B—C16—H16C109.5
O1—C9—C8105.0 (3)C14—C17—H17A109.5
O1—C9—H9A110.8C14—C17—H17B109.5
C8—C9—H9A110.8H17A—C17—H17B109.5
O1—C9—H9B110.8C14—C17—H17C109.5
C8—C9—H9B110.8H17A—C17—H17C109.5
H9A—C9—H9B108.8H17B—C17—H17C109.5
C6—C1—C2—C3−0.9 (6)C9—O1—C10—C73.9 (4)
C7—C1—C2—C3178.8 (4)C1—C7—C10—O1152.5 (3)
C1—C2—C3—C40.3 (7)O3—C7—C10—O1−88.3 (3)
C2—C3—C4—C50.4 (8)C8—C7—C10—O119.3 (4)
C3—C4—C5—C6−0.5 (8)C1—C7—C10—C11−90.8 (4)
C2—C1—C6—C50.9 (7)O3—C7—C10—C1128.5 (3)
C7—C1—C6—C5−178.8 (4)C8—C7—C10—C11136.0 (3)
C4—C5—C6—C1−0.2 (8)C13—N—C11—C10−116.8 (4)
C6—C1—C7—O3−138.5 (4)C13—N—C11—C12123.1 (4)
C2—C1—C7—O341.8 (4)O1—C10—C11—N−42.8 (4)
C6—C1—C7—C8106.1 (5)C7—C10—C11—N−155.7 (3)
C2—C1—C7—C8−73.6 (5)O1—C10—C11—C1282.5 (4)
C6—C1—C7—C10−21.4 (5)C7—C10—C11—C12−30.4 (4)
C2—C1—C7—C10158.9 (4)C7—O3—C12—O2178.3 (3)
C12—O3—C7—C1110.8 (3)C7—O3—C12—C11−3.7 (4)
C12—O3—C7—C8−124.7 (3)N—C11—C12—O2−32.6 (6)
C12—O3—C7—C10−15.9 (4)C10—C11—C12—O2−160.2 (4)
C1—C7—C8—C9−167.4 (3)N—C11—C12—O3149.5 (3)
O3—C7—C8—C974.6 (3)C10—C11—C12—O321.9 (4)
C10—C7—C8—C9−33.4 (4)C14—O5—C13—O4−2.5 (7)
C1—C7—C8—Cl−50.9 (4)C14—O5—C13—N178.3 (3)
O3—C7—C8—Cl−168.9 (2)C11—N—C13—O4−7.9 (6)
C10—C7—C8—Cl83.1 (3)C11—N—C13—O5171.3 (3)
C10—O1—C9—C8−25.6 (4)C13—O5—C14—C16−177.6 (4)
C7—C8—C9—O136.0 (4)C13—O5—C14—C17−60.5 (5)
Cl—C8—C9—O1−79.9 (3)C13—O5—C14—C1563.4 (5)
C9—O1—C10—C11−107.7 (3)
references
References top

Erdsack, J. & Krause, N. (2007). Synthesis In preparation. Update?

Erdsack, J., Schürmann, M., Preut, H. & Krause, N. (2007). Acta Cryst. E63, o664–o665.

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Hoffmann-Röder, A. & Krause, N. (2001). Org. Lett. 3, 2537–2538.

Nonius (1998). COLLECT. Nonius BV, Delft, The Netherlands.

Otwinowski, Z. & Minor, W. (1997). Methods in Enzymology, Vol. 276, Macromolecular Crystallography, Part A, edited by C. W. Carter Jr & R. M. Sweet, pp. 307–326. New York: Academic Press.

Sheldrick, G. M. (1991). SHELXTL-Plus (Release 4.1). Siemens Analytical X-ray Instruments Inc., Madison, Wisconsin, USA.

Sheldrick, G. M. (1997). SHELXS97 and SHELXL97. University of Göttingen, Germany.

Spek, A. L. (2003). J. Appl. Cryst. 36, 7–13.