(3S,3aS,6R,6aR)-2-Oxohexa­hydro­furo[3,2-b]furan-3,6-diyl dibenzoate

Piccialli, V.; Oliviero, G.; Zaccaria, S.; Centore, R.; Tuzi, A.

doi:10.1107/S160053681302391X

organic compounds

CRYSTALLOGRAPHIC
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ISSN: 2056-9890

Volume 69| Part 10| October 2013| Pages o1494-o1495

doi:10.1107/S160053681302391X

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(3S,3aS,6R,6aR)-2-Oxohexahydrofuro[3,2-b]furan-3,6-diyl dibenzoate

Vincenzo Piccialli,^a ^* Giorgia Oliviero,^b Sabrina Zaccaria,^a Roberto Centore ^a and Angela Tuzi ^a ^*

^aDipartimento di Scienze Chimiche, Università degli Studi di Napoli 'Federico II', Complesso di Monte S. Angelo, Via Cinthia, 80126 Napoli, Italy, and ^bDipartimento di Farmacia, Università degli Studi di Napoli 'Federico II', Via D. Montesano 49, 80131 Napoli, Italy
^*Correspondence e-mail: vinpicci@unina.it, angela.tuzi@unina.it

(Received 26 July 2013; accepted 26 August 2013; online 4 September 2013)

The title compound, C₂₀H₁₆O₇, contains a cis-fused γ-lactone tetrahydrofuran ring system functionalized with two benzoyloxy groups. Both rings adopt an envelope conformation. The molecule assumes an elongated shape and exibits non-crystallographic C₂ symmetry. The benzoyloxy groups are almost planar [maximum deviations of 0.0491 (15) and 0.0336 (17) Å for the O atoms] and their mean planes are inclined to one another by 16.51 (4)°. The crystal packing features weak C—H⋯O interactions. The aryl groups of adjacent molecules are parallel shifted with face-to-face contacts and a shortest intermolecular C⋯C distance of 3.482 (4) Å.

Related literature

For the use of carbohydrate in the synthesis of complex natural chiral substances, see: Hanessian (1993 ). For mannitol as chiral reagent and as a precursor of biologically active derivatives, see: Masaki et al. (1999 ); Lohray et al. (1999 ). For oxidative processes mediated by transition metal oxo-species, see: De Champdorè et al.. (1998 ); Piccialli (2007 ); Piccialli, Oliviero et al. (2013 ); Piccialli, Tuzi et al. (2013 ). For the catalytic use of chlorochromatoperiodate, see: Piccialli, D'Errico et al. (2013 ); Piccialli et al. (2012 ). For the synthesis of the precursor, see: Hockett et al. (1946 ).

Experimental

Crystal data

C₂₀H₁₆O₇
M_r = 368.33
Orthorhombic, P 2₁ 2₁ 2₁
a = 7.4870 (7) Å
b = 10.2050 (14) Å
c = 22.232 (2) Å
V = 1698.6 (3) Å³
Z = 4
Mo Kα radiation
μ = 0.11 mm⁻¹
T = 173 K
0.50 × 0.40 × 0.08 mm

Data collection

Bruker–Nonius KappaCCD diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2001 ) T_min = 0.947, T_max = 0.991
8078 measured reflections
2108 independent reflections
1797 reflections with I > 2σ(I)
R_int = 0.032

Refinement

R[F² > 2σ(F²)] = 0.034
wR(F²) = 0.078
S = 1.07
2108 reflections
244 parameters
H-atom parameters constrained
Δρ_max = 0.16 e Å⁻³
Δρ_min = −0.19 e Å⁻³

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C2—H2⋯O6ⁱ	1.00	2.34	2.974 (2)	121
C3—H3⋯O4ⁱⁱ	1.00	2.51	3.356 (3)	142
C10—H10⋯O7ⁱⁱⁱ	0.95	2.48	3.353 (3)	154
Symmetry codes: (i) $[x+{\script{1\over 2}}, -y+{\script{3\over 2}}, -z+1]$ ; (ii) $[x-{\script{1\over 2}}, -y+{\script{1\over 2}}, -z+1]$ ; (iii) x, y-1, z.

Data collection: COLLECT (Nonius, 1999 ); cell refinement: DIRAX/LSQ (Duisenberg et al., 2000 ); data reduction: EVALCCD (Duisenberg et al., 2003 ); program(s) used to solve structure: SIR97 (Altomare et al., 1999 ); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ); molecular graphics: ORTEP-3 for Windows (Farrugia, 2012 ) and Mercury (Macrae et al., 2006 ); software used to prepare material for publication: WinGX (Farrugia, 2012).

Supporting information

Crystal structure: contains datablocks global, I. DOI: 10.1107/S160053681302391X/zp2007sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S160053681302391X/zp2007Isup2.hkl

Supporting information file. DOI: 10.1107/S160053681302391X/zp2007Isup3.cml

checkCIF report

Comment top

D-mannitol plays an important role in organic synthesis as a readily available chiral building block (Hanessian, 1993). In addition, mannitol and its derivatives are widely used as chiral reagents and chiral auxiliaries (Masaki et al., 1999) and can be transformed into biologically active and pharmaceutically important compounds (Lohray et al., 1999). As a part of our ongoing interest in oxidative processes mediated by transition metals oxo-species (De Champdorè et al.. 1998; Piccialli, Oliviero, Borbone et al., 2013; Piccialli, Tuzi, Oliviero et al., 2013; Piccialli, 2007), and in particular in the synthesis of new THF-containing compounds, we recently focused on the catalytic use of chlorochromatoperiodate (CCP), a powerful oxidizing reagent generated by the condensation of pyridinium chlorochromate (PCC) and periodic acid (Piccialli, D'Errico, Borbone et al., 2013; Piccialli, Zaccaria, Oliviero et al., 2012).

The title compound, C₂₀H₁₈O₇, contains a functionalized cis–fused γ-lactone-tetrahydrofuran ring system, substituted at C2 and C5 positions with benzoyloxy groups. Both rings adopt an envelope conformation with O2 and C3 at the flap. The molecule assumes an elongated shape and exibits a C₂ symmetry of the benzoyloxy groups (Fig.2). The benzoyloxy groups are almost planar (maximum deviation from least square plane (O3/O4/C7—C13) is -0.0491 (15) Å for O3; maximum deviation from least square plane (O5/O6/C14—C20) is 0.0336 (17) Å for O6) and their mean planes are inclined with respect to each other by 16.51 (4)°. No strong H–bonding donor groups are present in the molecule. The crystal packing (Fig.3) is stabilized by weak intermolecular CH···O interactions. Aryl groups of adjacent molecules are parallel shifted with face-to-face contacts (shortest intermolecular distance is C12···C17ⁱ = 3.482 (4) Å, i = 1 + x, -1 + y, z).

Related literature top

For the use of carbohydrate in the synthesis of complex natural chiral substances, see: Hanessian (1993). For mannitol as chiral reagent and as a precursor of biologically active derivatives, see: Masaki et al. (1999); Lohray et al. (1999). For oxidative processes mediated by transition metal oxo-species, see: De Champdorè et al.. (1998); Piccialli (2007); Piccialli, Oliviero, Borbone et al. (2013); Piccialli, Tuzi, Oliviero et al. (2013). For the catalytic use of chlorochromatoperiodate, see: Piccialli, D'Errico, Borbone et al. (2013); Piccialli, Zaccaria, Oliviero et al. (2012). For the synthesis of the precursor, see: Hockett et al. (1946).

Experimental top

The title compound 2 has been synthesized by oxidation of bis-tetrahydrofuran 1 with chlorochromatoperiodate (CCP) according to the scheme in Fig. 1. Compound 1 has been obtained from mannitol according to literature (Hockett et al., 1946). Since the oxidative process does not affect any of the chiral centres of the molecule, the absolute configuration of 2 matches that of mannitol. Crystals suitable for X-ray analysis were obtained by recrystallization of 2 from methanol.

Compound 2: ¹H-NMR (200 MHz, CDCl₃) 8.23–8.03 (4H, m), 7.62 (2H, t, J= 7.6 Hz), 7.48 (4H, t, J= 7.5 Hz), 5.63 (1H, d, J= 5.6 Hz, H-2), 5.58–5.34 (2H, overlapped multiplets, H-4 and H-5), 5.06 (1H, dd, J= 5.6, 4.0 Hz, H-3), 4.33 (1H, dd, J= 9.3, 6.9 Hz, Ha-6), 4.03 (1H, dd, J= 9.3, 7.8 Hz, Hb-6); ¹³C-NMR (50 MHz, CDCl₃) 170.4, 165.8, 165.3, 133.9, 133.7, 130.2, 130.0, 129.8, 128.65, 128.56, 128.4, 128.2, 78.6, 76.1, 72.9, 69.4, 69.2.

Computing details top

Data collection: COLLECT (Nonius, 1999); cell refinement: DIRAX/LSQ (Duisenberg et al., 2000); data reduction: EVALCCD (Duisenberg et al., 2003); program(s) used to solve structure: SIR97 (Altomare et al., 1999); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 for Windows (Farrugia, 2012) and Mercury (Macrae et al., 2006); software used to prepare material for publication: WinGX (Farrugia, 2012).

Figures top

	Fig. 1. Synthesis of the title compound by chlorochromatoperiodate (CCP) catalyzed oxidation of 1.
	Fig. 2. ORTEP view of the the title compound. Thermal ellipsoids are drawn at 30% probability level.
	Fig. 3. Crystal packing viewed along b axis. Shortest aryl intermolecular C···C distance is shown as dashed line (i = 1 + x, -1 + y, z).

(3S,3aS,6R,6aR)-2-Oxohexahydrofuro[3,2-b]furan-3,6-diyl dibenzoate top

Crystal data top

C₂₀H₁₆O₇	F(000) = 768
M_r = 368.33	D_x = 1.440 Mg m⁻³
Orthorhombic, P2₁2₁2₁	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2ac 2ab	Cell parameters from 119 reflections
a = 7.4870 (7) Å	θ = 3.8–22.3°
b = 10.2050 (14) Å	µ = 0.11 mm⁻¹
c = 22.232 (2) Å	T = 173 K
V = 1698.6 (3) Å³	Block, white
Z = 4	0.50 × 0.40 × 0.08 mm

Data collection top

Bruker–Nonius KappaCCD diffractometer	2108 independent reflections
Radiation source: normal-focus sealed tube	1797 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.032
Detector resolution: 9 pixels mm^-1	θ_max = 27.5°, θ_min = 3.3°
CCD rotation images, thick slices scans	h = −9→5
Absorption correction: multi-scan (SADABS; Bruker, 2001)	k = −12→13
T_min = 0.947, T_max = 0.991	l = −28→28
8078 measured reflections

Refinement top

Refinement on F²	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F² > 2σ(F²)] = 0.034	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.078	H-atom parameters constrained
S = 1.07	w = 1/[σ²(F_o²) + (0.0383P)² + 0.2376P] where P = (F_o² + 2F_c²)/3
2108 reflections	(Δ/σ)_max < 0.001
244 parameters	Δρ_max = 0.16 e Å⁻³
0 restraints	Δρ_min = −0.19 e Å⁻³

Crystal data top

C₂₀H₁₆O₇	V = 1698.6 (3) Å³
M_r = 368.33	Z = 4
Orthorhombic, P2₁2₁2₁	Mo Kα radiation
a = 7.4870 (7) Å	µ = 0.11 mm⁻¹
b = 10.2050 (14) Å	T = 173 K
c = 22.232 (2) Å	0.50 × 0.40 × 0.08 mm

Data collection top

Bruker–Nonius KappaCCD diffractometer	2108 independent reflections
Absorption correction: multi-scan (SADABS; Bruker, 2001)	1797 reflections with I > 2σ(I)
T_min = 0.947, T_max = 0.991	R_int = 0.032
8078 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.034	0 restraints
wR(F²) = 0.078	H-atom parameters constrained
S = 1.07	Δρ_max = 0.16 e Å⁻³
2108 reflections	Δρ_min = −0.19 e Å⁻³
244 parameters

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	U_iso*/U_eq
C1	0.7473 (3)	0.5893 (2)	0.57766 (9)	0.0274 (5)
C2	0.7006 (3)	0.45523 (19)	0.55289 (9)	0.0256 (5)
H2	0.7605	0.4416	0.5132	0.031*
C3	0.5016 (3)	0.46156 (19)	0.54459 (9)	0.0248 (5)
H3	0.4587	0.4085	0.5096	0.030*
C4	0.4649 (3)	0.60851 (19)	0.53746 (9)	0.0260 (5)
H4	0.4546	0.6345	0.4942	0.031*
C5	0.2879 (3)	0.6297 (2)	0.57190 (9)	0.0276 (5)
H5	0.1904	0.6574	0.5439	0.033*
C6	0.2490 (3)	0.4957 (2)	0.59859 (11)	0.0324 (5)
H6A	0.2004	0.5045	0.6398	0.039*
H6B	0.1612	0.4480	0.5735	0.039*
C7	0.7436 (3)	0.2341 (2)	0.57841 (9)	0.0277 (5)
C8	0.8031 (3)	0.1437 (2)	0.62616 (9)	0.0267 (5)
C9	0.7809 (3)	0.0097 (2)	0.61663 (11)	0.0350 (6)
H9	0.7348	−0.0215	0.5795	0.042*
C10	0.8264 (4)	−0.0772 (2)	0.66150 (12)	0.0425 (7)
H10	0.8131	−0.1687	0.6551	0.051*
C11	0.8912 (4)	−0.0320 (2)	0.71559 (12)	0.0425 (6)
H11	0.9204	−0.0925	0.7465	0.051*
C12	0.9142 (4)	0.1007 (2)	0.72531 (11)	0.0369 (6)
H12	0.9591	0.1314	0.7627	0.044*
C13	0.8714 (3)	0.1880 (2)	0.68034 (10)	0.0320 (5)
H13	0.8889	0.2793	0.6865	0.038*
C14	0.3130 (3)	0.8490 (2)	0.60421 (9)	0.0271 (5)
C15	0.3326 (3)	0.9379 (2)	0.65625 (9)	0.0256 (5)
C16	0.3399 (3)	1.0720 (2)	0.64556 (10)	0.0330 (5)
H16	0.3290	1.1049	0.6058	0.040*
C17	0.3629 (4)	1.1568 (2)	0.69311 (11)	0.0381 (6)
H17	0.3679	1.2485	0.6860	0.046*
C18	0.3788 (4)	1.1098 (2)	0.75109 (10)	0.0382 (6)
H18	0.3943	1.1689	0.7837	0.046*
C19	0.3722 (4)	0.9768 (2)	0.76157 (10)	0.0349 (6)
H19	0.3843	0.9443	0.8014	0.042*
C20	0.3479 (3)	0.8907 (2)	0.71458 (9)	0.0282 (5)
H20	0.3418	0.7992	0.7221	0.034*
O1	0.6118 (2)	0.67337 (13)	0.56690 (6)	0.0276 (4)
O2	0.4158 (2)	0.42772 (14)	0.59961 (6)	0.0294 (4)
O3	0.7629 (2)	0.36076 (13)	0.59524 (6)	0.0272 (4)
O4	0.6838 (3)	0.20348 (14)	0.53016 (7)	0.0386 (4)
O5	0.3071 (2)	0.72131 (13)	0.62053 (6)	0.0268 (4)
O6	0.3053 (3)	0.88274 (15)	0.55255 (6)	0.0438 (5)
O7	0.8798 (2)	0.62237 (15)	0.60320 (8)	0.0403 (4)

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
C1	0.0279 (12)	0.0252 (11)	0.0292 (11)	−0.0009 (10)	0.0049 (10)	−0.0007 (8)
C2	0.0339 (14)	0.0222 (10)	0.0206 (9)	0.0002 (10)	0.0014 (9)	−0.0017 (8)
C3	0.0318 (13)	0.0251 (11)	0.0177 (9)	−0.0011 (10)	−0.0012 (9)	−0.0012 (8)
C4	0.0293 (13)	0.0264 (11)	0.0221 (10)	−0.0009 (10)	−0.0022 (9)	−0.0007 (8)
C5	0.0300 (13)	0.0289 (11)	0.0239 (10)	0.0003 (10)	−0.0025 (10)	−0.0022 (9)
C6	0.0274 (13)	0.0300 (12)	0.0397 (12)	−0.0024 (10)	0.0035 (11)	−0.0020 (9)
C7	0.0276 (12)	0.0250 (11)	0.0304 (11)	0.0039 (10)	0.0073 (10)	−0.0055 (8)
C8	0.0243 (12)	0.0254 (11)	0.0304 (10)	0.0043 (9)	0.0051 (10)	−0.0006 (9)
C9	0.0356 (15)	0.0260 (12)	0.0434 (13)	0.0029 (11)	0.0049 (12)	−0.0042 (9)
C10	0.0460 (17)	0.0242 (12)	0.0572 (16)	0.0052 (12)	0.0121 (14)	0.0036 (11)
C11	0.0402 (15)	0.0370 (13)	0.0504 (14)	0.0098 (12)	0.0072 (14)	0.0157 (12)
C12	0.0339 (15)	0.0401 (13)	0.0368 (12)	0.0060 (12)	−0.0029 (11)	0.0037 (10)
C13	0.0300 (13)	0.0286 (12)	0.0373 (12)	0.0045 (10)	−0.0009 (11)	0.0006 (9)
C14	0.0267 (13)	0.0269 (11)	0.0278 (10)	0.0039 (10)	−0.0028 (10)	0.0047 (9)
C15	0.0216 (12)	0.0292 (11)	0.0260 (10)	0.0011 (9)	0.0022 (9)	0.0012 (8)
C16	0.0365 (15)	0.0301 (11)	0.0323 (11)	−0.0007 (11)	0.0047 (10)	0.0066 (9)
C17	0.0419 (16)	0.0269 (11)	0.0455 (13)	−0.0077 (11)	0.0102 (12)	−0.0020 (10)
C18	0.0389 (15)	0.0370 (13)	0.0388 (12)	−0.0091 (12)	0.0047 (12)	−0.0110 (10)
C19	0.0364 (15)	0.0432 (13)	0.0252 (10)	−0.0033 (12)	0.0007 (10)	−0.0004 (10)
C20	0.0284 (13)	0.0292 (11)	0.0270 (10)	−0.0002 (10)	0.0008 (9)	0.0040 (9)
O1	0.0274 (9)	0.0222 (7)	0.0332 (8)	−0.0002 (7)	0.0008 (7)	−0.0023 (6)
O2	0.0310 (9)	0.0285 (7)	0.0289 (7)	−0.0023 (7)	0.0029 (7)	0.0048 (6)
O3	0.0341 (9)	0.0211 (7)	0.0263 (7)	0.0024 (6)	−0.0015 (7)	−0.0005 (6)
O4	0.0540 (12)	0.0322 (8)	0.0297 (8)	0.0067 (8)	−0.0043 (8)	−0.0092 (6)
O5	0.0332 (9)	0.0238 (7)	0.0233 (7)	0.0034 (7)	−0.0001 (7)	−0.0001 (6)
O6	0.0734 (14)	0.0335 (8)	0.0245 (7)	0.0041 (9)	−0.0101 (9)	0.0054 (6)
O7	0.0302 (10)	0.0341 (9)	0.0568 (10)	−0.0025 (8)	−0.0076 (9)	−0.0079 (8)

Geometric parameters (Å, º) top

C1—O7	1.191 (3)	C9—C10	1.377 (3)
C1—O1	1.350 (3)	C9—H9	0.9500
C1—C2	1.516 (3)	C10—C11	1.376 (4)
C2—O3	1.426 (2)	C10—H10	0.9500
C2—C3	1.502 (3)	C11—C12	1.381 (4)
C2—H2	1.0000	C11—H11	0.9500
C3—O2	1.424 (2)	C12—C13	1.377 (3)
C3—C4	1.533 (3)	C12—H12	0.9500
C3—H3	1.0000	C13—H13	0.9500
C4—O1	1.441 (3)	C14—O6	1.200 (2)
C4—C5	1.545 (3)	C14—O5	1.353 (2)
C4—H4	1.0000	C14—C15	1.477 (3)
C5—O5	1.436 (2)	C15—C20	1.388 (3)
C5—C6	1.519 (3)	C15—C16	1.390 (3)
C5—H5	1.0000	C16—C17	1.377 (3)
C6—O2	1.428 (3)	C16—H16	0.9500
C6—H6A	0.9900	C17—C18	1.381 (3)
C6—H6B	0.9900	C17—H17	0.9500
C7—O4	1.204 (3)	C18—C19	1.378 (3)
C7—O3	1.354 (2)	C18—H18	0.9500
C7—C8	1.475 (3)	C19—C20	1.377 (3)
C8—C13	1.385 (3)	C19—H19	0.9500
C8—C9	1.394 (3)	C20—H20	0.9500

O7—C1—O1	121.98 (19)	C10—C9—H9	120.3
O7—C1—C2	128.4 (2)	C8—C9—H9	120.3
O1—C1—C2	109.61 (19)	C11—C10—C9	120.3 (2)
O3—C2—C3	115.75 (18)	C11—C10—H10	119.9
O3—C2—C1	107.13 (16)	C9—C10—H10	119.9
C3—C2—C1	103.58 (18)	C10—C11—C12	120.6 (2)
O3—C2—H2	110.0	C10—C11—H11	119.7
C3—C2—H2	110.0	C12—C11—H11	119.7
C1—C2—H2	110.0	C13—C12—C11	119.5 (2)
O2—C3—C2	109.37 (17)	C13—C12—H12	120.3
O2—C3—C4	104.18 (16)	C11—C12—H12	120.3
C2—C3—C4	103.46 (18)	C12—C13—C8	120.4 (2)
O2—C3—H3	113.0	C12—C13—H13	119.8
C2—C3—H3	113.0	C8—C13—H13	119.8
C4—C3—H3	113.0	O6—C14—O5	122.07 (19)
O1—C4—C3	105.38 (17)	O6—C14—C15	125.32 (19)
O1—C4—C5	111.41 (15)	O5—C14—C15	112.60 (16)
C3—C4—C5	103.87 (17)	C20—C15—C16	119.9 (2)
O1—C4—H4	111.9	C20—C15—C14	121.81 (18)
C3—C4—H4	111.9	C16—C15—C14	118.32 (19)
C5—C4—H4	111.9	C17—C16—C15	119.5 (2)
O5—C5—C6	108.12 (16)	C17—C16—H16	120.2
O5—C5—C4	112.23 (18)	C15—C16—H16	120.2
C6—C5—C4	103.39 (18)	C16—C17—C18	120.6 (2)
O5—C5—H5	110.9	C16—C17—H17	119.7
C6—C5—H5	110.9	C18—C17—H17	119.7
C4—C5—H5	110.9	C19—C18—C17	119.8 (2)
O2—C6—C5	106.02 (19)	C19—C18—H18	120.1
O2—C6—H6A	110.5	C17—C18—H18	120.1
C5—C6—H6A	110.5	C20—C19—C18	120.3 (2)
O2—C6—H6B	110.5	C20—C19—H19	119.8
C5—C6—H6B	110.5	C18—C19—H19	119.8
H6A—C6—H6B	108.7	C19—C20—C15	119.9 (2)
O4—C7—O3	122.27 (19)	C19—C20—H20	120.0
O4—C7—C8	126.27 (19)	C15—C20—H20	120.0
O3—C7—C8	111.46 (17)	C1—O1—C4	111.24 (15)
C13—C8—C9	119.8 (2)	C3—O2—C6	105.25 (16)
C13—C8—C7	122.24 (19)	C7—O3—C2	115.35 (16)
C9—C8—C7	117.9 (2)	C14—O5—C5	115.34 (15)
C10—C9—C8	119.5 (2)

O7—C1—C2—O3	39.4 (3)	C7—C8—C13—C12	175.6 (2)
O1—C1—C2—O3	−140.40 (18)	O6—C14—C15—C20	−177.3 (3)
O7—C1—C2—C3	162.3 (2)	O5—C14—C15—C20	1.7 (3)
O1—C1—C2—C3	−17.6 (2)	O6—C14—C15—C16	1.2 (4)
O3—C2—C3—O2	31.1 (2)	O5—C14—C15—C16	−179.9 (2)
C1—C2—C3—O2	−85.81 (19)	C20—C15—C16—C17	0.2 (4)
O3—C2—C3—C4	141.68 (16)	C14—C15—C16—C17	−178.3 (2)
C1—C2—C3—C4	24.7 (2)	C15—C16—C17—C18	0.0 (4)
O2—C3—C4—O1	90.05 (19)	C16—C17—C18—C19	0.2 (4)
C2—C3—C4—O1	−24.3 (2)	C17—C18—C19—C20	−0.6 (4)
O2—C3—C4—C5	−27.2 (2)	C18—C19—C20—C15	0.9 (4)
C2—C3—C4—C5	−141.55 (16)	C16—C15—C20—C19	−0.6 (4)
O1—C4—C5—O5	7.1 (2)	C14—C15—C20—C19	177.8 (2)
C3—C4—C5—O5	120.05 (18)	O7—C1—O1—C4	−177.88 (19)
O1—C4—C5—C6	−109.20 (19)	C2—C1—O1—C4	2.0 (2)
C3—C4—C5—C6	3.8 (2)	C3—C4—O1—C1	14.2 (2)
O5—C5—C6—O2	−98.2 (2)	C5—C4—O1—C1	126.26 (18)
C4—C5—C6—O2	20.9 (2)	C2—C3—O2—C6	151.80 (17)
O4—C7—C8—C13	179.6 (3)	C4—C3—O2—C6	41.7 (2)
O3—C7—C8—C13	−0.8 (3)	C5—C6—O2—C3	−39.8 (2)
O4—C7—C8—C9	−3.5 (4)	O4—C7—O3—C2	2.5 (3)
O3—C7—C8—C9	176.2 (2)	C8—C7—O3—C2	−177.11 (18)
C13—C8—C9—C10	0.4 (4)	C3—C2—O3—C7	69.5 (2)
C7—C8—C9—C10	−176.7 (2)	C1—C2—O3—C7	−175.54 (18)
C8—C9—C10—C11	0.8 (4)	O6—C14—O5—C5	−1.1 (3)
C9—C10—C11—C12	−1.1 (4)	C15—C14—O5—C5	179.92 (18)
C10—C11—C12—C13	0.1 (4)	C6—C5—O5—C14	−169.6 (2)
C11—C12—C13—C8	1.1 (4)	C4—C5—O5—C14	77.1 (2)
C9—C8—C13—C12	−1.3 (4)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
C2—H2···O6ⁱ	1.00	2.34	2.974 (2)	121
C3—H3···O4ⁱⁱ	1.00	2.51	3.356 (3)	142
C10—H10···O7ⁱⁱⁱ	0.95	2.48	3.353 (3)	154

Symmetry codes: (i) x+1/2, −y+3/2, −z+1; (ii) x−1/2, −y+1/2, −z+1; (iii) x, y−1, z.

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
C2—H2···O6ⁱ	1.00	2.34	2.974 (2)	120.7
C3—H3···O4ⁱⁱ	1.00	2.51	3.356 (3)	141.5
C10—H10···O7ⁱⁱⁱ	0.95	2.48	3.353 (3)	153.6

Symmetry codes: (i) x+1/2, −y+3/2, −z+1; (ii) x−1/2, −y+1/2, −z+1; (iii) x, y−1, z.

Acknowledgements

The authors thank the Centro Interdipartimentale di Metodologie Chimico–Fisiche, Università degli Studi di Napoli "Federico II" for X-ray and NMR facilities.

References

Altomare, A., Burla, M. C., Camalli, M., Cascarano, G. L., Giacovazzo, C., Guagliardi, A., Moliterni, A. G. G., Polidori, G. & Spagna, R. (1999). J. Appl. Cryst. 32, 115–119. Web of Science CrossRef CAS IUCr Journals Google Scholar
Bruker . (2001). SADABS. Bruker AXS Inc., Madison, Wisconsin, USA. Google Scholar
De Champdorè, M., Lasalvia, M. & Piccialli, V. (1998). Tetrahedron Lett. 39, 9781–9784. Google Scholar
Duisenberg, A. J. M., Hooft, R. W. W., Schreurs, A. M. M. & Kroon, J. (2000). J. Appl. Cryst. 33, 893–898. Web of Science CrossRef CAS IUCr Journals Google Scholar
Duisenberg, A. J. M., Kroon-Batenburg, L. M. J. & Schreurs, A. M. M. (2003). J. Appl. Cryst. 36, 220–229. Web of Science CrossRef CAS IUCr Journals Google Scholar
Farrugia, L. J. (2012). J. Appl. Cryst. 45, 849–854. Web of Science CrossRef CAS IUCr Journals Google Scholar
Hanessian, S. (1993). Total synthesis of natural products `Chiron approach'. Organic Chemistry Series, edited by J. E. Baldwin. New York: Pergamon Press. Google Scholar
Hockett, R. C., Fletcher, H. G. Jr, Sheffield, E., Goepp, R. M. Jr & Soltzberg, S. (1946). J. Am. Chem. Soc. pp. 930–935. CrossRef Web of Science Google Scholar
Lohray, B. B., Baskaran, S., Rao, B. S., Reddy, B. Y. & Rao, I. N. (1999). Tetrahedron Lett. 40, 4855–4856. Web of Science CrossRef CAS Google Scholar
Macrae, C. F., Edgington, P. R., McCabe, P., Pidcock, E., Shields, G. P., Taylor, R., Towler, M. & van de Streek, J. (2006). J. Appl. Cryst. 39, 453–457. Web of Science CrossRef CAS IUCr Journals Google Scholar
Masaki, Y., Arasaki, H. & Itoh, A. (1999). Tetrahedron Lett. 40, 4829–4832. Web of Science CSD CrossRef CAS Google Scholar
Nonius, B. V. (1999). COLLECT. Nonius BV, Delft, The Netherlands. Google Scholar
Piccialli, V. (2007). Synthesis, pp. 2585–2607. Web of Science CrossRef Google Scholar
Piccialli, V., D'Errico, S., Borbone, N., Oliviero, G., Centore, R. & Zaccaria, S. (2013). Eur. J. Org. Chem. pp. 1781–1789. Web of Science CSD CrossRef Google Scholar
Piccialli, V., Oliviero, G., Borbone, N., Centore, R. & Tuzi, A. (2013). Acta Cryst. E69, o879–o880. CSD CrossRef CAS IUCr Journals Google Scholar
Piccialli, V., Tuzi, A., Oliviero, G., Borbone, N. & Centore, R. (2013). Acta Cryst. E69, o1109–o1110. CSD CrossRef CAS IUCr Journals Google Scholar
Piccialli, V., Zaccaria, S., Oliviero, G., D'Errico, S., D'Atri, V. & Borbone, N. (2012). Eur. J. Org. Chem. pp. 4293–4305. Web of Science CrossRef Google Scholar
Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. Web of Science CrossRef CAS IUCr Journals Google Scholar