supplementary materials


ff2087 scheme

Acta Cryst. (2012). E68, o3331    [ doi:10.1107/S1600536812045278 ]

Westphalen's diol diacetate: 19(10[rightwards arrow]5)-abeo-5[beta]-cholest-9-ene-3[beta],6[beta]-diyl diacetate

J. Ramírez Hernández, J. Sandoval-Ramírez, S. Meza-Reyes, J. L. Vega Báez and S. Bernès

Abstract top

The structure of the title steroid [alternative name: 3[beta],6[beta]-diacetoxy-5[beta]-methyl-19-norcholest-9(10)-ene], C31H50O4, confirms the generally accepted mechanism for the rearrangement of a cholestan-5[alpha]-ol derivative reported a century ago by Westphalen. The methyl group at position 10 of the starting material migrates to position 5 in the steroidal nucleus, while a [Delta]9 bond is formed, as indicated by the C=C bond length of 1.347 (4) Å. The methyl transposition leaves the 5R configuration unchanged, with the methyl oriented towards the [beta] face. During the rearrangement, the steroidal B ring experiences a conformational distortion from chair to envelope with the C atom at position 6 as the flap. In the title structure, the isopropyl group of the side chain is disordered over two positions, with occupancies of 0.733 (10) and 0.267 (10). The carbonyl O atom in the acetyl group at C3 is also disordered with an occupancy ratio of 0.62 (4):0.38 (4).

Comment top

The Westphalen rearrangement is a useful synthetic tool in steroid chemistry, involving, for example, a 10β to 5β methyl shift, which has been used for the preparation of Δ9 steroids and 19-nor steroidal derivatives. It was originally applied in the cholestane series, and was further expanded, for instance, to 20-ketopregnanes (Rodig et al., 1961), and more recently, to androstane (Knights & Hanson, 2004) and pregnane series (Pinto et al., 2008, 2009). The mechanism of the rearrangement has been studied (Kočovský & Černý, 1977; Kočovský et al., 1979), although it is not fully understood in a general case, because complex competing reaction pathways are in action (for a review on these mechanisms, see section 2 in Kamernitskii et al., 1987, and references cited therein). A consensus has been reached, however, for products prepared under the Westphalen conditions in the cholestane series. Treatment with acetic anhydride and sulfuric acid promotes dehydration of the cholestan-5α-ol substrate, and the resulting carbocation is rearranged through the methyl 1,2-shift, before formation of the olefinic bond Δ9. The empty p orbital of the carbocation is electronically stabilized by the electron density of the O atom of the acetate at C6. With such a mechanism, a single epimer is expected as product, with the methyl at C5 oriented towards the β face. This stereochemistry has been confirmed in all the studied cases, but, surprisingly, the product of the very first report by Westphalen (1915) was never X-ray characterized.

During a study on the optimization of reaction conditions for the Westphalen rearrangement carried out on 5-hydroxy-5α-cholestane-3β,6β-diyl diacetate, which was the substrate used by Westphalen, we obtained in 80% yield the rearrangement product (see Experimental). The molecular structure (Fig. 1) and the absolute configuration for chiral centers are as expected. The saturated A and C rings have a chair conformation, while the B ring, which includes the C9C10 double bond, is distorted to a half-chair conformation, close to an envelope with C6 as flap. Finally, the D ring adopts a half-chair conformation twisted on C13—C14. The observed conformation is indeed very similar to that described by Pinto et al. (2008) for the closely related derivative 3β-acetoxy-6β-hydroxy-5β-methyl-19-norcholest-9(10)-ene. An overlay between the steroidal nucleus of this structure and that of the title molecule gives a r.m.s. deviation limited to 0.156 Å, the largest deviation arising from the side chain. This group presents a degree of flexibility, as reflected by the disorder detected in the title compound for the isopropyl group. The same conformation for the A-D ring system was also observed for a Westphalen product in the pregnane series (Pinto et al., 2009).

Related literature top

For the initial report on the Westphalen rearrangement, see: Westphalen (1915). For applications in steroid synthesis, see: Rodig et al. (1961); Knights & Hanson (2004); Pinto et al. (2008, 2009). For mechanistic aspects of this rearrangement, see: Kočovský & Černý (1977); Kočovský et al. (1979); Kamernitskii et al. (1987).

Experimental top

5-Hydroxy-5α-cholestane-3β,6β-diyl diacetate (6.1 g, 12.09 mmol) was treated with acetic anhydride (150 ml) for 20 min at 363 K. Then, NaHSO4 was added (1.74 g, 12.78 mmol) and stirred until complete consumption of the starting material (ca. 30 min). The mixture was poured in a 500 ml Erlenmeyer with pyridine and ice and vigorously stirred. The product, which deposited on the glass vessel, was dissolved in ethyl acetate, and then washed with saline solution, 5% HCl, distilled water, and finally 10% NaHCO3. This phase was dried over Na2SO4, and the solvent evaporated under reduced pressure. The crude (80% yield) was chromatographed over silicagel with petroleum ether and ethyl acetate (95:5) and crystallized from ethyl acetate. When KHSO4 was used, the Westphalen compound was obtained in 35% yield.

Refinement top

The isopropyl group in the lateral chain was found to be disordered over two positions, C251/C261/C271 and C252/C262/C272, and occupancies converged to 0.733 (10) and 0.267 (10), respectively. Both parts were restrained to have similar displacement parameters and geometry (SIMU and SAME restraints; Sheldrick, 2008). On the other side of the molecule, the carbonyl O atom in the acetyl group at C3 is also disordered over two sites, O301 and O302, with occupancies 0.62 (4) and 0.38 (4). All H atoms were placed in calculated positions and refined as riding to their carrier C atoms. C—H bond lengths were set to 0.96 (methyl) 0.97 (methylene) or 0.98 Å (methine), and isotropic parameters for H atoms were calculated as Uiso(H) = xUeq(carrier C) with x = 1.5 (methyl) or x = 1.2 (methylene and methine groups). Friedel pairs (714) were merged, and absolute configuration assigned by fixing the configuration of known chiral centers.

Computing details top

Data collection: XSCANS (Siemens, 1996); cell refinement: XSCANS (Siemens, 1996); data reduction: XSCANS (Siemens, 1996); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).

Figures top
[Figure 1] Fig. 1. ORTEP view of the title molecule, with displacement ellipsoids for non-H atoms at the 30% probability level. For disordered parts, sites with occupancy less than 0.5 have been omitted.
19(10 5)-abeo-5β-cholest-9-ene-3β,6β-diyl diacetate top
Crystal data top
C31H50O4Dx = 1.083 Mg m3
Mr = 486.71Melting point: 393 K
Orthorhombic, P212121Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2ac 2abCell parameters from 70 reflections
a = 9.2846 (15) Åθ = 4.4–12.6°
b = 10.7203 (18) ŵ = 0.07 mm1
c = 29.982 (4) ÅT = 298 K
V = 2984.2 (8) Å3Prism, colourless
Z = 40.6 × 0.5 × 0.5 mm
F(000) = 1072
Data collection top
Siemens P4
diffractometer
Rint = 0.043
Radiation source: fine-focus sealed tubeθmax = 26.2°, θmin = 2.0°
Graphite monochromatorh = 111
ω scansk = 131
4350 measured reflectionsl = 371
3393 independent reflections3 standard reflections every 97 reflections
2827 reflections with I > 2σ(I) intensity decay: 0.5%
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)] = 0.048H-atom parameters constrained
wR(F2) = 0.136 w = 1/[σ2(Fo2) + (0.0701P)2 + 0.3625P]
where P = (Fo2 + 2Fc2)/3
S = 1.05(Δ/σ)max < 0.001
3393 reflectionsΔρmax = 0.14 e Å3
364 parametersΔρmin = 0.13 e Å3
57 restraintsExtinction correction: SHELXL97 (Sheldrick, 2008), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
0 constraintsExtinction coefficient: 0.0087 (15)
Primary atom site location: structure-invariant direct methods
Crystal data top
C31H50O4V = 2984.2 (8) Å3
Mr = 486.71Z = 4
Orthorhombic, P212121Mo Kα radiation
a = 9.2846 (15) ŵ = 0.07 mm1
b = 10.7203 (18) ÅT = 298 K
c = 29.982 (4) Å0.6 × 0.5 × 0.5 mm
Data collection top
Siemens P4
diffractometer
Rint = 0.043
4350 measured reflectionsθmax = 26.2°
3393 independent reflections3 standard reflections every 97 reflections
2827 reflections with I > 2σ(I) intensity decay: 0.5%
Refinement top
R[F2 > 2σ(F2)] = 0.048H-atom parameters constrained
wR(F2) = 0.136Δρmax = 0.14 e Å3
S = 1.05Δρmin = 0.13 e Å3
3393 reflectionsAbsolute structure: ?
364 parametersFlack parameter: ?
57 restraintsRogers parameter: ?
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/UeqOcc. (<1)
C10.2670 (3)0.4760 (3)0.61696 (10)0.0641 (7)
H1A0.24660.54010.59500.077*
H1B0.18140.46480.63510.077*
C20.3009 (4)0.3544 (3)0.59299 (9)0.0726 (8)
H2A0.21870.32990.57510.087*
H2B0.38210.36700.57310.087*
C30.3362 (3)0.2514 (3)0.62582 (9)0.0650 (7)
H3A0.36500.17610.60960.078*
C40.4562 (3)0.2908 (3)0.65690 (9)0.0606 (7)
H4A0.54540.29120.64010.073*
H4B0.46560.22780.67990.073*
C50.4402 (3)0.4198 (2)0.68004 (8)0.0527 (6)
C60.5907 (3)0.4565 (2)0.69696 (8)0.0532 (6)
H6A0.65940.44810.67230.064*
C70.5959 (3)0.5892 (2)0.71400 (7)0.0574 (6)
H7A0.68990.60630.72670.069*
H7B0.52400.60070.73710.069*
C80.5666 (3)0.6791 (2)0.67539 (7)0.0516 (6)
H8A0.53610.75880.68830.062*
C90.4467 (3)0.6345 (2)0.64463 (7)0.0507 (5)
C100.3898 (3)0.5190 (2)0.64651 (8)0.0514 (6)
C110.4104 (3)0.7329 (3)0.61009 (8)0.0585 (6)
H11A0.37270.80630.62500.070*
H11B0.33620.70120.59040.070*
C120.5432 (3)0.7699 (3)0.58233 (8)0.0586 (6)
H12A0.51730.83800.56260.070*
H12B0.57150.69960.56390.070*
C130.6728 (3)0.8100 (2)0.61110 (8)0.0517 (6)
C140.6972 (3)0.7048 (2)0.64575 (7)0.0513 (6)
H14A0.71290.62850.62850.062*
C150.8427 (3)0.7366 (3)0.66716 (8)0.0632 (7)
H15A0.88910.66250.67890.076*
H15B0.83140.79700.69100.076*
C160.9295 (3)0.7920 (3)0.62790 (9)0.0659 (7)
H16A1.00630.73560.61930.079*
H16B0.97180.87120.63650.079*
C170.8231 (3)0.8106 (3)0.58856 (8)0.0551 (6)
H17A0.82850.73500.57030.066*
C180.6419 (3)0.9375 (3)0.63309 (10)0.0661 (7)
H18A0.55660.93150.65110.099*
H18B0.62790.99940.61040.099*
H18C0.72200.96100.65150.099*
C190.3317 (3)0.4091 (3)0.71907 (8)0.0590 (6)
H19A0.35840.34050.73790.089*
H19B0.23670.39530.70740.089*
H19C0.33260.48490.73610.089*
C200.8656 (3)0.9204 (3)0.55802 (9)0.0666 (7)
H20Z0.85800.99740.57550.080*
C210.7641 (4)0.9322 (5)0.51798 (12)0.1005 (13)
H21A0.66820.94940.52830.151*
H21B0.76430.85550.50140.151*
H21C0.79600.99900.49910.151*
C221.0228 (4)0.9080 (3)0.54214 (11)0.0741 (8)
H22A1.08460.90120.56810.089*
H22B1.03210.83110.52530.089*
C231.0756 (4)1.0143 (4)0.51364 (15)0.0984 (12)
H23A1.05901.09180.52950.118*
H23B1.01861.01680.48660.118*
C241.2325 (4)1.0079 (4)0.50092 (13)0.0883 (10)
H24A1.25870.92110.49690.106*0.733 (10)
H24B1.28931.04020.52550.106*0.733 (10)
H24C1.24310.94320.47860.106*0.267 (10)
H24D1.28620.98140.52700.106*0.267 (10)
C2511.2727 (7)1.0799 (5)0.4585 (3)0.088 (2)0.733 (10)
H25A1.21271.04540.43460.105*0.733 (10)
C2611.2338 (10)1.2166 (6)0.4617 (3)0.116 (3)0.733 (10)
H26A1.13141.22490.46510.175*0.733 (10)
H26B1.26401.25870.43510.175*0.733 (10)
H26C1.28121.25280.48700.175*0.733 (10)
C2711.4250 (7)1.0578 (8)0.4448 (3)0.127 (3)0.733 (10)
H27A1.44790.97110.44830.190*0.733 (10)
H27B1.48811.10700.46310.190*0.733 (10)
H27C1.43721.08120.41410.190*0.733 (10)
C2521.3037 (13)1.1263 (15)0.4829 (5)0.076 (4)0.267 (10)
H25B1.28281.19720.50250.092*0.267 (10)
C2621.233 (4)1.145 (4)0.4374 (8)0.192 (14)0.267 (10)
H26D1.13581.11400.43830.288*0.267 (10)
H26E1.28631.10100.41510.288*0.267 (10)
H26F1.23121.23250.43030.288*0.267 (10)
C2721.4604 (18)1.109 (3)0.4784 (16)0.204 (14)0.267 (10)
H27D1.50241.09780.50730.306*0.267 (10)
H27E1.50161.18200.46460.306*0.267 (10)
H27F1.47951.03750.46020.306*0.267 (10)
O280.2039 (2)0.22733 (18)0.65042 (8)0.0734 (6)
C290.1753 (4)0.1143 (3)0.66520 (13)0.0832 (10)
O3010.2663 (9)0.0327 (8)0.6663 (4)0.095 (3)0.62 (4)
O3020.228 (4)0.0265 (18)0.6439 (17)0.186 (12)0.38 (4)
C310.0398 (4)0.1098 (4)0.69085 (16)0.1018 (12)
H31A0.02540.02690.70220.153*
H31B0.03920.13200.67180.153*
H31C0.04510.16740.71530.153*
O320.63096 (19)0.36908 (19)0.73216 (5)0.0608 (5)
C330.7731 (3)0.3523 (3)0.73874 (9)0.0630 (7)
O340.8643 (2)0.4020 (3)0.71683 (8)0.0900 (8)
C350.8011 (3)0.2691 (3)0.77742 (10)0.0759 (8)
H35A0.90280.25460.78000.114*
H35B0.75240.19110.77300.114*
H35C0.76620.30790.80420.114*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
C10.0599 (16)0.0645 (16)0.0680 (16)0.0031 (14)0.0182 (13)0.0092 (13)
C20.0761 (18)0.0797 (19)0.0621 (14)0.0114 (17)0.0165 (15)0.0051 (15)
C30.0641 (16)0.0630 (16)0.0680 (15)0.0010 (14)0.0006 (13)0.0091 (13)
C40.0592 (15)0.0591 (15)0.0635 (14)0.0069 (13)0.0008 (13)0.0015 (12)
C50.0540 (13)0.0563 (13)0.0478 (11)0.0030 (12)0.0023 (11)0.0047 (11)
C60.0536 (13)0.0625 (14)0.0436 (11)0.0021 (12)0.0039 (11)0.0126 (11)
C70.0614 (14)0.0685 (15)0.0423 (10)0.0083 (13)0.0085 (11)0.0050 (11)
C80.0563 (14)0.0524 (13)0.0462 (11)0.0029 (12)0.0032 (11)0.0014 (10)
C90.0485 (12)0.0577 (13)0.0460 (11)0.0033 (12)0.0038 (10)0.0042 (11)
C100.0481 (12)0.0595 (13)0.0466 (11)0.0009 (12)0.0067 (10)0.0054 (11)
C110.0557 (14)0.0617 (14)0.0580 (13)0.0024 (13)0.0094 (12)0.0116 (12)
C120.0628 (15)0.0628 (15)0.0503 (12)0.0024 (13)0.0088 (11)0.0135 (12)
C130.0532 (13)0.0533 (13)0.0487 (11)0.0003 (11)0.0001 (11)0.0031 (11)
C140.0545 (13)0.0561 (13)0.0431 (11)0.0013 (12)0.0045 (10)0.0027 (10)
C150.0590 (15)0.0795 (18)0.0512 (12)0.0108 (15)0.0083 (11)0.0059 (13)
C160.0588 (15)0.0781 (18)0.0608 (14)0.0087 (15)0.0020 (12)0.0067 (14)
C170.0582 (14)0.0583 (14)0.0487 (11)0.0006 (12)0.0014 (11)0.0027 (11)
C180.0716 (17)0.0560 (14)0.0709 (15)0.0020 (14)0.0103 (15)0.0015 (13)
C190.0593 (15)0.0602 (15)0.0576 (13)0.0002 (12)0.0054 (12)0.0065 (13)
C200.0692 (17)0.0693 (16)0.0614 (14)0.0007 (15)0.0067 (14)0.0113 (13)
C210.086 (2)0.133 (3)0.083 (2)0.017 (2)0.0076 (19)0.054 (2)
C220.0759 (19)0.0755 (19)0.0708 (16)0.0012 (16)0.0130 (15)0.0091 (16)
C230.085 (2)0.093 (3)0.116 (3)0.004 (2)0.036 (2)0.030 (2)
C240.077 (2)0.093 (2)0.095 (2)0.0035 (19)0.0192 (18)0.014 (2)
C2510.081 (3)0.089 (4)0.094 (4)0.031 (3)0.022 (3)0.009 (3)
C2610.131 (6)0.089 (4)0.129 (6)0.019 (4)0.030 (5)0.025 (4)
C2710.085 (4)0.140 (6)0.156 (7)0.028 (4)0.051 (5)0.004 (5)
C2520.073 (7)0.076 (8)0.080 (8)0.024 (7)0.001 (7)0.014 (7)
C2620.21 (3)0.23 (3)0.14 (2)0.06 (3)0.01 (2)0.07 (2)
C2720.094 (13)0.19 (3)0.32 (4)0.067 (16)0.03 (2)0.03 (3)
O280.0671 (12)0.0578 (11)0.0954 (14)0.0046 (10)0.0088 (11)0.0056 (11)
C290.082 (2)0.0616 (18)0.107 (2)0.0112 (18)0.0187 (19)0.0178 (18)
O3010.096 (4)0.056 (4)0.132 (6)0.021 (3)0.031 (4)0.009 (3)
O3020.22 (2)0.100 (8)0.24 (3)0.058 (10)0.132 (19)0.068 (12)
C310.091 (2)0.079 (2)0.135 (3)0.015 (2)0.029 (2)0.012 (2)
O320.0512 (9)0.0758 (12)0.0553 (9)0.0015 (9)0.0064 (8)0.0217 (9)
C330.0545 (15)0.0722 (17)0.0622 (14)0.0075 (14)0.0023 (13)0.0093 (14)
O340.0587 (11)0.1137 (19)0.0976 (15)0.0029 (12)0.0072 (11)0.0390 (15)
C350.0668 (17)0.087 (2)0.0740 (16)0.0147 (17)0.0089 (15)0.0185 (16)
Geometric parameters (Å, º) top
C1—C101.516 (4)C19—H19C0.9600
C1—C21.521 (4)C20—C211.532 (5)
C1—H1A0.9700C20—C221.541 (4)
C1—H1B0.9700C20—H20Z0.9800
C2—C31.516 (4)C21—H21A0.9600
C2—H2A0.9700C21—H21B0.9600
C2—H2B0.9700C21—H21C0.9600
C3—O281.456 (3)C22—C231.507 (4)
C3—C41.513 (4)C22—H22A0.9700
C3—H3A0.9800C22—H22B0.9700
C4—C51.554 (4)C23—C241.507 (5)
C4—H4A0.9700C23—H23A0.9700
C4—H4B0.9700C23—H23B0.9700
C5—C101.537 (3)C24—C2511.534 (7)
C5—C61.538 (4)C24—C2521.530 (14)
C5—C191.548 (3)C24—H24A0.9700
C6—O321.460 (3)C24—H24B0.9700
C6—C71.513 (4)C24—H24C0.9700
C6—H6A0.9800C24—H24D0.9699
C7—C81.530 (3)C251—C2611.512 (8)
C7—H7A0.9700C251—C2711.492 (8)
C7—H7B0.9700C251—H25A0.9800
C8—C91.523 (3)C261—H26A0.9600
C8—C141.528 (3)C261—H26B0.9600
C8—H8A0.9800C261—H26C0.9600
C9—C101.347 (4)C271—H27A0.9600
C9—C111.516 (3)C271—H27B0.9600
C11—C121.539 (4)C271—H27C0.9600
C11—H11A0.9700C252—C2621.529 (17)
C11—H11B0.9700C252—C2721.473 (17)
C12—C131.542 (4)C252—H25B0.9800
C12—H12A0.9700C262—H26D0.9600
C12—H12B0.9700C262—H26E0.9600
C13—C181.545 (4)C262—H26F0.9600
C13—C141.550 (3)C272—H27D0.9600
C13—C171.550 (3)C272—H27E0.9600
C14—C151.535 (3)C272—H27F0.9600
C14—H14A0.9800O28—C291.317 (4)
C15—C161.545 (4)C29—O3011.216 (7)
C15—H15A0.9700C29—O3021.238 (17)
C15—H15B0.9700C29—C311.475 (5)
C16—C171.551 (4)C31—H31A0.9600
C16—H16A0.9700C31—H31B0.9600
C16—H16B0.9700C31—H31C0.9600
C17—C201.543 (4)O32—C331.346 (3)
C17—H17A0.9800C33—O341.197 (3)
C18—H18A0.9600C33—C351.486 (4)
C18—H18B0.9600C35—H35A0.9600
C18—H18C0.9600C35—H35B0.9600
C19—H19A0.9600C35—H35C0.9600
C19—H19B0.9600
C10—C1—C2112.4 (2)C16—C17—H17A106.6
C10—C1—H1A109.1C13—C18—H18A109.5
C2—C1—H1A109.1C13—C18—H18B109.5
C10—C1—H1B109.1H18A—C18—H18B109.5
C2—C1—H1B109.1C13—C18—H18C109.5
H1A—C1—H1B107.8H18A—C18—H18C109.5
C3—C2—C1111.3 (2)H18B—C18—H18C109.5
C3—C2—H2A109.4C5—C19—H19A109.5
C1—C2—H2A109.4C5—C19—H19B109.5
C3—C2—H2B109.4H19A—C19—H19B109.5
C1—C2—H2B109.4C5—C19—H19C109.5
H2A—C2—H2B108.0H19A—C19—H19C109.5
O28—C3—C4111.0 (2)H19B—C19—H19C109.5
O28—C3—C2106.0 (2)C21—C20—C22110.3 (3)
C4—C3—C2110.8 (2)C21—C20—C17111.8 (3)
O28—C3—H3A109.6C22—C20—C17111.1 (2)
C4—C3—H3A109.6C21—C20—H20Z107.8
C2—C3—H3A109.6C22—C20—H20Z107.8
C3—C4—C5117.0 (2)C17—C20—H20Z107.8
C3—C4—H4A108.1C20—C21—H21A109.5
C5—C4—H4A108.1C20—C21—H21B109.5
C3—C4—H4B108.1H21A—C21—H21B109.5
C5—C4—H4B108.1C20—C21—H21C109.5
H4A—C4—H4B107.3H21A—C21—H21C109.5
C10—C5—C6108.4 (2)H21B—C21—H21C109.5
C10—C5—C19110.4 (2)C23—C22—C20114.7 (3)
C6—C5—C19111.16 (19)C23—C22—H22A108.6
C10—C5—C4110.67 (19)C20—C22—H22A108.6
C6—C5—C4106.7 (2)C23—C22—H22B108.6
C19—C5—C4109.5 (2)C20—C22—H22B108.6
O32—C6—C7110.59 (19)H22A—C22—H22B107.6
O32—C6—C5107.9 (2)C22—C23—C24115.1 (3)
C7—C6—C5112.4 (2)C22—C23—H23A108.5
O32—C6—H6A108.6C24—C23—H23A108.5
C7—C6—H6A108.6C22—C23—H23B108.5
C5—C6—H6A108.6C24—C23—H23B108.5
C6—C7—C8109.34 (18)H23A—C23—H23B107.5
C6—C7—H7A109.8C23—C24—C251115.0 (4)
C8—C7—H7A109.8C23—C24—C252118.0 (6)
C6—C7—H7B109.8C23—C24—H24A108.5
C8—C7—H7B109.8C23—C24—H24B108.5
H7A—C7—H7B108.3C23—C24—H24C107.8
C9—C8—C14106.51 (18)C23—C24—H24D107.8
C9—C8—C7113.0 (2)C251—C24—H24A108.5
C14—C8—C7114.4 (2)C251—C24—H24B108.5
C9—C8—H8A107.6C252—C24—H24C107.8
C14—C8—H8A107.6C252—C24—H24D107.8
C7—C8—H8A107.6H24A—C24—H24B107.5
C10—C9—C11125.5 (2)H24C—C24—H24D107.1
C10—C9—C8123.4 (2)C261—C251—C271113.5 (6)
C11—C9—C8111.0 (2)C261—C251—C24112.1 (6)
C9—C10—C1123.4 (2)C271—C251—C24112.3 (6)
C9—C10—C5123.0 (2)C261—C251—H25A106.1
C1—C10—C5113.6 (2)C271—C251—H25A106.1
C9—C11—C12111.7 (2)C24—C251—H25A106.1
C9—C11—H11A109.3C262—C252—C272111.1 (19)
C12—C11—H11A109.3C262—C252—C24103.8 (18)
C9—C11—H11B109.3C272—C252—C24111.0 (15)
C12—C11—H11B109.3C262—C252—H25B110.3
H11A—C11—H11B107.9C272—C252—H25B110.3
C11—C12—C13113.2 (2)C24—C252—H25B110.3
C11—C12—H12A108.9C252—C262—H26D109.5
C13—C12—H12A108.9C252—C262—H26E109.5
C11—C12—H12B108.9C252—C262—H26F109.5
C13—C12—H12B108.9H26D—C262—H26E109.5
H12A—C12—H12B107.7H26D—C262—H26F109.5
C12—C13—C18109.9 (2)H26E—C262—H26F109.5
C12—C13—C14106.6 (2)C252—C272—H27D109.5
C18—C13—C14112.64 (19)C252—C272—H27E109.5
C12—C13—C17117.36 (19)C252—C272—H27F109.5
C18—C13—C17110.5 (2)H27D—C272—H27E109.5
C14—C13—C1799.4 (2)H27D—C272—H27F109.5
C8—C14—C15119.70 (18)H27E—C272—H27F109.5
C8—C14—C13113.9 (2)C29—O28—C3120.2 (3)
C15—C14—C13104.3 (2)O301—C29—O28122.1 (5)
C8—C14—H14A106.0O302—C29—O28116.5 (14)
C15—C14—H14A106.0O301—C29—C31123.7 (5)
C13—C14—H14A106.0O302—C29—C31125.5 (10)
C14—C15—C16103.04 (19)O28—C29—C31112.2 (3)
C14—C15—H15A111.2C29—C31—H31A109.5
C16—C15—H15A111.2C29—C31—H31B109.5
C14—C15—H15B111.2H31A—C31—H31B109.5
C16—C15—H15B111.2C29—C31—H31C109.5
H15A—C15—H15B109.1H31A—C31—H31C109.5
C15—C16—C17107.3 (2)H31B—C31—H31C109.5
C15—C16—H16A110.3C33—O32—C6116.3 (2)
C17—C16—H16A110.3O34—C33—O32123.6 (3)
C15—C16—H16B110.3O34—C33—C35124.9 (3)
C17—C16—H16B110.3O32—C33—C35111.5 (2)
H16A—C16—H16B108.5C33—C35—H35A109.5
C20—C17—C13119.5 (2)C33—C35—H35B109.5
C20—C17—C16112.7 (2)H35A—C35—H35B109.5
C13—C17—C16103.94 (19)C33—C35—H35C109.5
C20—C17—H17A106.6H35A—C35—H35C109.5
C13—C17—H17A106.6H35B—C35—H35C109.5
C10—C1—C2—C357.8 (3)C12—C13—C14—C858.3 (3)
C1—C2—C3—O2866.2 (3)C18—C13—C14—C862.3 (3)
C1—C2—C3—C454.4 (3)C17—C13—C14—C8179.29 (19)
O28—C3—C4—C568.0 (3)C12—C13—C14—C15169.4 (2)
C2—C3—C4—C549.5 (3)C18—C13—C14—C1570.0 (3)
C3—C4—C5—C1044.6 (3)C17—C13—C14—C1547.0 (2)
C3—C4—C5—C6162.4 (2)C8—C14—C15—C16164.2 (2)
C3—C4—C5—C1977.2 (3)C13—C14—C15—C1635.3 (3)
C10—C5—C6—O32174.13 (19)C14—C15—C16—C179.6 (3)
C19—C5—C6—O3252.7 (3)C12—C13—C17—C2079.2 (3)
C4—C5—C6—O3266.6 (2)C18—C13—C17—C2047.9 (3)
C10—C5—C6—C751.9 (2)C14—C13—C17—C20166.5 (2)
C19—C5—C6—C769.5 (3)C12—C13—C17—C16154.1 (2)
C4—C5—C6—C7171.17 (19)C18—C13—C17—C1678.8 (3)
O32—C6—C7—C8174.9 (2)C14—C13—C17—C1639.8 (2)
C5—C6—C7—C864.5 (3)C15—C16—C17—C20150.2 (3)
C6—C7—C8—C941.3 (3)C15—C16—C17—C1319.4 (3)
C6—C7—C8—C1480.8 (3)C13—C17—C20—C2160.8 (3)
C14—C8—C9—C10115.5 (3)C16—C17—C20—C21176.7 (3)
C7—C8—C9—C1010.9 (3)C13—C17—C20—C22175.5 (2)
C14—C8—C9—C1160.0 (3)C16—C17—C20—C2253.0 (3)
C7—C8—C9—C11173.6 (2)C21—C20—C22—C2358.0 (4)
C11—C9—C10—C17.3 (4)C17—C20—C22—C23177.5 (3)
C8—C9—C10—C1177.8 (2)C20—C22—C23—C24175.5 (3)
C11—C9—C10—C5174.8 (2)C22—C23—C24—C252164.3 (8)
C8—C9—C10—C50.0 (4)C22—C23—C24—C251156.2 (4)
C2—C1—C10—C9128.1 (3)C23—C24—C251—C26157.6 (8)
C2—C1—C10—C553.8 (3)C252—C24—C251—C26146.2 (10)
C6—C5—C10—C919.8 (3)C23—C24—C251—C271173.3 (5)
C19—C5—C10—C9102.2 (3)C252—C24—C251—C27182.9 (11)
C4—C5—C10—C9136.5 (3)C23—C24—C252—C272172 (2)
C6—C5—C10—C1162.2 (2)C251—C24—C252—C27294 (2)
C19—C5—C10—C175.9 (3)C23—C24—C252—C26269 (2)
C4—C5—C10—C145.5 (3)C251—C24—C252—C26225.6 (19)
C10—C9—C11—C12118.3 (3)C4—C3—O28—C2991.3 (3)
C8—C9—C11—C1257.1 (3)C2—C3—O28—C29148.3 (3)
C9—C11—C12—C1353.6 (3)C3—O28—C29—O30113.5 (9)
C11—C12—C13—C1870.6 (3)C3—O28—C29—O30228 (3)
C11—C12—C13—C1451.7 (3)C3—O28—C29—C31177.6 (3)
C11—C12—C13—C17162.0 (2)C7—C6—O32—C3382.4 (3)
C9—C8—C14—C15172.7 (2)C5—C6—O32—C33154.3 (2)
C7—C8—C14—C1547.2 (3)C6—O32—C33—O342.0 (4)
C9—C8—C14—C1362.9 (3)C6—O32—C33—C35175.8 (2)
C7—C8—C14—C13171.6 (2)
Acknowledgements top

We thank VIEP–BUAP for financial support.

references
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