Ethyl 1-O-tert-butyl­dimethyl­silyl-2,3-O-isopropyl­idene-5-[(2′S)-tetra­hydro­pyran-2-yl­oxy]-d-glycero-α-d-manno-hepto­furonate

Soengas, R.G.; Valencia, L.; Estévez, J.C.; Estévez, R.J.

doi:10.1107/S1600536808021193

organic compounds

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ISSN: 2056-9890

Volume 64| Part 8| August 2008| Page o1478

doi:10.1107/S1600536808021193

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Ethyl 1-O-tert-butyldimethylsilyl-2,3-O-isopropylidene-5-[(2′S)-tetrahydropyran-2-yloxy]-D-glycero-α-D-manno-heptofuronate

Raquel G. Soengas,^a Laura Valencia,^b Juan C. Estévez ^a and Ramón J. Estévez ^a ^*

^aDepartamento de Química Orgánica, Universidade de Santiago de Compostela, 15782 Santiago de Compostela, Spain, and ^bDepartamento de Química Inorgánica, Facultade de Química, Universidad de Vigo, 36310 Vigo, Pontevedra, Spain
^*Correspondence e-mail: ramon.estevez@usc.es

(Received 29 May 2008; accepted 8 July 2008; online 12 July 2008)

The title compound {systematic name: (2S,3R)-ethyl 3-[(3aS,4R,6S,6aS)-6-tert-butyldimethylsilyloxy-2,2-dimethylperhydrofuro[3,4-d][1,3]dioxol-4-yl]-2-nitro-3-[(S)-tetrahydro-2H-pyran-2-yloxy]propanoate}, C₂₃H₄₁NO₁₀Si, is the product of the Henry reaction of 1-O-tert-butyldimethylsilyl-2,3-O-isopropylidene-α-D-lyxo-pentadialdo-1,4-furanose with ethyl nitroacetate and the subsequent protection of its C-5 hydroxy group as tetrahydropyranyl, in order to avoid the retro-Henry reaction. The tetrahydropyranyl group adopts a chair conformation. The absolute configuration, assumed from the synthesis, was confirmed from the diffraction data.

Related literature

For the preparation of the aldehyde precursor of the title compound, see: Brewster et al. (1987 ). For the Henry reaction, see: Soengas et al. (2003a ). For the protection as tetrahydropyran, see: Soengas et al. (2003b ). For other related literature, see: Gruner et al. (2002 ); Lillelund et al. (2002 ); Ogawa et al. (2005 ); Chakraborty et al. (2002 ).

Experimental

Crystal data

C₂₃H₄₁NO₁₀Si
M_r = 519.66
Orthorhombic, P 2₁ 2₁ 2₁
a = 15.593 (3) Å
b = 9.563 (4) Å
c = 19.690 (3) Å
V = 2935.9 (15) Å³
Z = 4
Cu Kα radiation
μ = 1.13 mm⁻¹
T = 293 (2) K
0.48 × 0.40 × 0.32 mm

Data collection

Enraf–Nonius TurboCAD-4 diffractometer
Absorption correction: ψ scan (North et al., 1968 ) T_min = 0.614, T_max = 0.714
6473 measured reflections
5898 independent reflections
3434 reflections with I > 2σ(I)
R_int = 0.037
3 standard reflections every 167 reflections intensity decay: 4%

Refinement

R[F² > 2σ(F²)] = 0.066
wR(F²) = 0.264
S = 1.11
5898 reflections
325 parameters
H-atom parameters constrained
Δρ_max = 0.21 e Å⁻³
Δρ_min = −0.27 e Å⁻³
Absolute structure: Flack (1983 ), 2569 Friedel pairs
Flack parameter: 0.04 (8)

Data collection: CAD-4 EXPRESS (Enraf–Nonius, 1994 ); cell refinement: CAD-4 EXPRESS; data reduction: XCAD4 (Harms & Wocadlo, 1995 ); 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, 1997 ); software used to prepare material for publication: WinGX (Farrugia, 1999 ).

Supporting information

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536808021193/cf2203sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536808021193/cf2203Isup2.hkl

checkCIF report

Comment top

Nitro-sugars are very important as precursors of a wide range of natural and synthetic products with relevant properties (Gruner et al., 2002), as aminopoliols (Lillelund et al.., 2002; Ogawa et al., 2005), polyhydroxylated amino acids (Chakraborty et al.., 2002), etc. The title nitro-sugar compound (3), C₂₃H₄₁NO₁₀Si, is the product of the Henry reaction (Soengas et al., 2003a) of 1-O-tert-butyldimethylsilyl-2,3-O-isopropylidene-a-D-lyxo-pentadialdo-1,4-furanose (1) (Brewster et al., 1987) with ethyl nitroacetate to give ethyl 1-O-tert-butyldimethylsilyl-2,3-O-isopropylidene-D-glycero-a-D-manno-heptofuronate (2) and the subsequent protection of its C5 hydroxy group as tetrahydropyranyl (Soengas et al., 2003b), in order to avoid the retro Henry reaction. The molecular structure is represented in Fig. 1. Bond lengths and angles are within the expected values. The tetrahydropyranyl group adopts a chair conformation. The absolute configuration was assumed from the synthesis and confirmed by the X-ray crystal structure determination.

Related literature top

For the preparation of the aldehyde precursor of the title compound, see: Brewster et al. (1987). For the Henry reaction, see: Soengas et al. (2003a). For the protection as tetrahydropyran, see: Soengas et al. (2003b). For other related literature, see: Gruner et al. (2002); Lillelund et al. (2002); Ogawa et al. (2005); Chakraborty et al. (2002).

Experimental top

Ethyl nitroacetate (0.26 ml, 2.36 mmol) and sodium methoxide (1.12 g, 2.28 mmol) were added to a solution of 1-O-tert-butyldimethylsilyl-2,3-O-isopropylidene-α-D-lyxo-pentadialdo-1,4-furanose (1) (0.62 g, 2.1 mmol) in dry methanol (6 ml), cooled at 273 K under argon. The reaction mixture was stirred at room temperature for 5 h and then neutralized with DOWEX 50W resin, filtered, evaporated in vacuo, and the resulting residue submitted to flash column chromatography (ethyl acetate/hexane 1:6) to give the epimeric mixture of ethyl 1-O-tert-butyldimethylsilyl-2,3-O-isopropylidene-D-glycero-a-D-manno-heptofuronate (2) (0.63 g, 70% yield) as an unstable gum.

Dry tetrahydropyran (0.39 ml, 4.32 mmol) and pyridinium p-toluenesulfonate (0.12 g, 0.43 mmol) were added to a solution of the above epimeric mixture (0.63 g, 1.45 mmol) in dry dichloromethane (12 ml). The solution was stirred at room temperature for 24 h, then diethyl ether (18 ml) was added and the mixture washed with brine (12 ml), dried with anhydrous sodium sulfate, filtered and evaporated in vacuo to give a residue that was purified by flash column chromatography (ethyl acetate/hexane 1:9) to give an oil; after crystallization from hexane this gave the title compound (3) (0.24 g, 32%) as a white crystalline solid. mp 369–370 K; [a]_D²⁰ +108.0° (c, 1 in CHCl₃); IR (NaCl, cm^-1) 1762 (C=O), 1569, 1373 (NO₂); ¹H NMR (300 MHz, CDCl₃) δ 0.09, 0.13 (2 × s, 6H, SiMe₂); 0.89 (s, 9H, Si^tBu); 1.30 (t, 3H, J = 7.2 Hz, –CH₃); 1.32, 1.46 (2 × s, 6H, –CH₃); 1.54–1.72 (m, 6H, OTHP); 3.56–3.69 (m, 1H, OTHP); 3.83–3.89 (m, 1H, OTHP); 4.15–4.36 (m, 2H); 4.55 (d, 1H, J_3,4 = 5.5 Hz, H3); 4.66 (dd, 1H, J_2,1 = 3.8 Hz, J_3,2 = 9.5 Hz, H2); 4.74–4.79 (m, 2H); 4.96 (s, 1H), 5.23 (s, 1H), 5.81 (d, 1H, J_1,2 = 3.8 Hz, H1). ¹³C NMR (75.4 MHz, CDCl₃) δ -5.86, -4.60, 13.93, 17.88, 18.88, 25.06, 25.18, 25.15, 25.56, 26.15, 30.58, 62.44, 74.51,77.80, 79.85, 86.69, 89.78, 101.05, 101.44, 112.50, 162.32. MS(EI) (m/z,%) 504 (M⁺-15, 0.1), 436 (1), 190 (3), 129 (14), 85 (100); Found C 53.15, H 7.94, N 2.74 C₂₃H₄₁NO₁₀Si requires C 53.16, H 7.95, N 2.70. The reaction scheme is shown in Fig. 2. Crystals for X-ray diffraction were obtained from ethanol.

Computing details top

Data collection: CAD-4 EXPRESS (Enraf–Nonius, 1994); cell refinement: CAD-4 EXPRESS (Enraf–Nonius, 1994); data reduction: XCAD4 (Harms & Wocadlo, 1995); 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, 1997); software used to prepare material for publication: WinGX (Farrugia, 1999).

Figures top

	Fig. 1. The molecular structure of (3), with atom labels and 50% probability displacement ellipsoids. H atoms have been omitted.
	Fig. 2. Chemical reaction scheme.

(2S,3R)-ethyl 3-[(3aS,4R,6S,6aS)-6-tert- butyldimethylsilyloxy-2,2-dimethylperhydrofuro[3,4-d][1,3]dioxol- 4-yl]-2-nitro-3-[(S)-tetrahydro-2H-pyran-2-yloxy]propanoate top

Crystal data top

C₂₃H₄₁NO₁₀Si	D_x = 1.176 Mg m⁻³
M_r = 519.66	Cu Kα radiation, λ = 1.54184 Å
Orthorhombic, P2₁2₁2₁	Cell parameters from 18 reflections
a = 15.593 (3) Å	θ = 17.6–42.2°
b = 9.563 (4) Å	µ = 1.13 mm⁻¹
c = 19.690 (3) Å	T = 293 K
V = 2935.9 (15) Å³	Prism, colourless
Z = 4	0.48 × 0.40 × 0.32 mm
F(000) = 1120

Data collection top

Enraf–Nonius TurboCAD-4 diffractometer	3434 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	R_int = 0.037
Graphite monochromator	θ_max = 73.4°, θ_min = 3.6°
Non–profiled ω/2θ scans	h = −19→0
Absorption correction: ψ scan (North et al., 1968)	k = −11→0
T_min = 0.614, T_max = 0.714	l = −24→24
6473 measured reflections	3 standard reflections every 167 reflections
5898 independent reflections	intensity decay: 4%

Refinement top

Refinement on F²	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F² > 2σ(F²)] = 0.066	H-atom parameters constrained
wR(F²) = 0.264	w = 1/[σ²(F_o²) + (0.1249P)² + 1.1254P] where P = (F_o² + 2F_c²)/3
S = 1.11	(Δ/σ)_max < 0.001
5898 reflections	Δρ_max = 0.22 e Å⁻³
325 parameters	Δρ_min = −0.27 e Å⁻³
0 restraints	Absolute structure: Flack (1983), 2569 Friedel pairs
Primary atom site location: structure-invariant direct methods	Absolute structure parameter: 0.04 (8)

Crystal data top

C₂₃H₄₁NO₁₀Si	V = 2935.9 (15) Å³
M_r = 519.66	Z = 4
Orthorhombic, P2₁2₁2₁	Cu Kα radiation
a = 15.593 (3) Å	µ = 1.13 mm⁻¹
b = 9.563 (4) Å	T = 293 K
c = 19.690 (3) Å	0.48 × 0.40 × 0.32 mm

Data collection top

Enraf–Nonius TurboCAD-4 diffractometer	3434 reflections with I > 2σ(I)
Absorption correction: ψ scan (North et al., 1968)	R_int = 0.037
T_min = 0.614, T_max = 0.714	3 standard reflections every 167 reflections
6473 measured reflections	intensity decay: 4%
5898 independent reflections

Refinement top

R[F² > 2σ(F²)] = 0.066	H-atom parameters constrained
wR(F²) = 0.264	Δρ_max = 0.22 e Å⁻³
S = 1.11	Δρ_min = −0.27 e Å⁻³
5898 reflections	Absolute structure: Flack (1983), 2569 Friedel pairs
325 parameters	Absolute structure parameter: 0.04 (8)
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

	x	y	z	U_iso*/U_eq
O1	0.3708 (2)	0.3276 (4)	0.43815 (17)	0.0688 (9)
C2	0.4611 (3)	0.3178 (7)	0.4327 (3)	0.0722 (14)
H2	0.4895	0.3750	0.4673	0.087*
C3	0.4804 (3)	0.1651 (6)	0.4427 (3)	0.0713 (13)
H3	0.5281	0.1338	0.4142	0.086*
C4	0.3965 (3)	0.0870 (6)	0.4260 (3)	0.0696 (13)
H4	0.4041	0.0158	0.3908	0.084*
C5	0.3381 (3)	0.2059 (6)	0.4035 (2)	0.0666 (13)
H5	0.3447	0.2194	0.3545	0.080*
O6	0.4953 (2)	0.1368 (5)	0.51299 (19)	0.0879 (11)
C7	0.4381 (4)	0.0343 (7)	0.5360 (3)	0.0780 (15)
O8	0.3698 (2)	0.0295 (5)	0.4890 (2)	0.0854 (12)
C9	0.4844 (7)	−0.1044 (9)	0.5337 (7)	0.181 (6)
H9A	0.4487	−0.1755	0.5534	0.271*
H9B	0.5369	−0.0976	0.5589	0.271*
H9C	0.4969	−0.1282	0.4874	0.271*
C10	0.4081 (6)	0.0680 (17)	0.6031 (4)	0.194 (7)
H10A	0.3768	0.1545	0.6017	0.290*
H10B	0.4562	0.0774	0.6331	0.290*
H10C	0.3712	−0.0052	0.6191	0.290*
O11	0.4874 (2)	0.3565 (4)	0.36718 (17)	0.0756 (9)
Si12	0.50307 (12)	0.51726 (18)	0.33863 (9)	0.0858 (5)
C13	0.4458 (7)	0.6418 (10)	0.3943 (6)	0.166 (5)
H13A	0.3886	0.6087	0.4023	0.249*
H13B	0.4435	0.7318	0.3727	0.249*
H13C	0.4757	0.6497	0.4368	0.249*
C14	0.4610 (7)	0.5262 (12)	0.2497 (5)	0.148 (4)
H14A	0.4664	0.4362	0.2286	0.222*
H14B	0.4933	0.5939	0.2244	0.222*
H14C	0.4017	0.5532	0.2506	0.222*
C15	0.6207 (5)	0.5470 (9)	0.3385 (4)	0.107 (2)
C16	0.6623 (6)	0.4457 (13)	0.2889 (5)	0.156 (4)
H16A	0.7196	0.4765	0.2789	0.233*
H16B	0.6294	0.4425	0.2478	0.233*
H16C	0.6644	0.3541	0.3088	0.233*
C17	0.6555 (5)	0.5320 (17)	0.4098 (4)	0.173 (6)
H17A	0.6508	0.4363	0.4240	0.259*
H17B	0.6231	0.5904	0.4400	0.259*
H17C	0.7146	0.5599	0.4105	0.259*
C18	0.6407 (8)	0.6965 (12)	0.3132 (5)	0.175 (5)
H18A	0.7015	0.7115	0.3139	0.263*
H18B	0.6132	0.7633	0.3424	0.263*
H18C	0.6196	0.7075	0.2677	0.263*
C19	0.2448 (3)	0.1860 (7)	0.4193 (2)	0.0733 (15)
H19	0.2402	0.1481	0.4654	0.088*
O20	0.2148 (2)	0.0833 (5)	0.37335 (18)	0.0860 (12)
C21	0.1697 (4)	−0.0350 (9)	0.4032 (3)	0.099 (2)
H21	0.2024	−0.0686	0.4424	0.118*
C22	0.1651 (6)	−0.1488 (9)	0.3517 (4)	0.117 (3)
H22A	0.1470	−0.2345	0.3738	0.141*
H22B	0.2219	−0.1644	0.3331	0.141*
C23	0.1036 (7)	−0.1158 (13)	0.2942 (4)	0.141 (4)
H23A	0.1261	−0.0396	0.2670	0.169*
H23B	0.0971	−0.1971	0.2652	0.169*
C24	0.0191 (6)	−0.0760 (14)	0.3231 (5)	0.153 (4)
H24A	−0.0055	−0.1549	0.3471	0.184*
H24B	−0.0197	−0.0496	0.2869	0.184*
C25	0.0308 (5)	0.0476 (13)	0.3724 (5)	0.143 (4)
H25A	0.0524	0.1280	0.3476	0.172*
H25B	−0.0242	0.0725	0.3919	0.172*
O26	0.0894 (3)	0.0124 (7)	0.4255 (2)	0.1160 (17)
C27	0.1881 (4)	0.3190 (8)	0.4150 (3)	0.0892 (19)
H27	0.1297	0.2906	0.4273	0.107*
N28	0.1840 (4)	0.3743 (8)	0.3432 (3)	0.110 (2)
O29	0.2476 (3)	0.3920 (8)	0.3110 (3)	0.135 (2)
O30	0.1129 (4)	0.4028 (11)	0.3218 (3)	0.194 (4)
C31	0.2115 (5)	0.4367 (11)	0.4606 (4)	0.104 (2)
O32	0.2205 (4)	0.5543 (8)	0.4431 (4)	0.143 (2)
O33	0.2157 (3)	0.3927 (6)	0.5243 (2)	0.1067 (15)
C34	0.2439 (11)	0.4994 (13)	0.5745 (5)	0.188 (6)
H34A	0.2957	0.5446	0.5582	0.225*
H34B	0.1998	0.5702	0.5792	0.225*
C35	0.2591 (10)	0.4413 (15)	0.6345 (7)	0.204 (6)
H35A	0.2092	0.3909	0.6492	0.307*
H35B	0.2724	0.5129	0.6670	0.307*
H35C	0.3067	0.3781	0.6308	0.307*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
O1	0.0590 (17)	0.083 (2)	0.0645 (19)	0.0041 (17)	0.0043 (15)	0.0023 (17)
C2	0.062 (3)	0.092 (4)	0.063 (3)	0.001 (3)	0.003 (2)	−0.002 (3)
C3	0.060 (3)	0.088 (4)	0.067 (3)	0.002 (3)	0.007 (2)	0.015 (3)
C4	0.067 (3)	0.082 (3)	0.059 (3)	0.001 (3)	−0.002 (2)	0.001 (3)
C5	0.054 (2)	0.093 (4)	0.053 (2)	0.000 (2)	0.0011 (19)	−0.004 (2)
O6	0.0667 (19)	0.122 (3)	0.075 (2)	−0.020 (2)	−0.0152 (18)	0.030 (2)
C7	0.072 (3)	0.092 (4)	0.070 (3)	−0.010 (3)	−0.014 (2)	0.017 (3)
O8	0.070 (2)	0.104 (3)	0.082 (2)	−0.018 (2)	−0.0152 (18)	0.032 (2)
C9	0.160 (9)	0.090 (6)	0.292 (15)	−0.005 (6)	−0.124 (10)	0.046 (7)
C10	0.115 (6)	0.37 (2)	0.091 (5)	−0.079 (10)	0.017 (5)	−0.051 (8)
O11	0.074 (2)	0.084 (2)	0.0693 (19)	−0.0028 (19)	0.0122 (17)	0.0124 (17)
Si12	0.0864 (10)	0.0890 (11)	0.0821 (9)	−0.0053 (10)	−0.0054 (8)	0.0167 (9)
C13	0.180 (10)	0.097 (6)	0.221 (12)	0.021 (6)	0.074 (9)	0.001 (7)
C14	0.161 (8)	0.161 (9)	0.123 (6)	−0.035 (7)	−0.053 (6)	0.056 (7)
C15	0.107 (5)	0.140 (6)	0.075 (4)	−0.040 (5)	0.012 (4)	0.020 (4)
C16	0.123 (7)	0.198 (11)	0.146 (8)	−0.020 (7)	0.051 (6)	−0.017 (8)
C17	0.105 (6)	0.316 (17)	0.097 (6)	−0.070 (8)	−0.027 (4)	0.043 (8)
C18	0.204 (11)	0.182 (10)	0.140 (8)	−0.114 (9)	−0.012 (7)	0.043 (7)
C19	0.055 (2)	0.118 (5)	0.046 (2)	−0.001 (3)	−0.0017 (19)	0.005 (3)
O20	0.078 (2)	0.127 (3)	0.0523 (18)	−0.021 (2)	−0.0011 (17)	0.010 (2)
C21	0.085 (4)	0.145 (6)	0.067 (3)	−0.019 (4)	−0.009 (3)	0.013 (4)
C22	0.135 (6)	0.116 (6)	0.101 (5)	−0.029 (5)	0.007 (5)	0.016 (5)
C23	0.144 (8)	0.188 (10)	0.090 (5)	−0.059 (7)	−0.017 (5)	−0.007 (5)
C24	0.112 (7)	0.228 (12)	0.119 (7)	−0.055 (7)	−0.033 (5)	0.017 (7)
C25	0.088 (5)	0.213 (11)	0.129 (7)	−0.014 (6)	−0.036 (5)	0.006 (7)
O26	0.089 (3)	0.181 (5)	0.078 (3)	−0.028 (3)	0.007 (2)	0.010 (3)
C27	0.063 (3)	0.141 (6)	0.064 (3)	0.015 (3)	0.006 (2)	0.015 (4)
N28	0.080 (3)	0.169 (6)	0.080 (3)	0.041 (4)	0.001 (3)	0.033 (4)
O29	0.096 (3)	0.208 (6)	0.101 (3)	0.043 (4)	0.023 (3)	0.067 (4)
O30	0.095 (4)	0.361 (12)	0.125 (5)	0.065 (5)	−0.021 (3)	0.084 (6)
C31	0.083 (4)	0.132 (7)	0.099 (5)	0.043 (5)	0.008 (4)	0.005 (5)
O32	0.157 (5)	0.122 (5)	0.152 (6)	0.039 (4)	−0.002 (4)	0.018 (4)
O33	0.103 (3)	0.138 (4)	0.079 (3)	0.026 (3)	0.010 (2)	−0.013 (3)
C34	0.318 (17)	0.149 (9)	0.096 (7)	0.064 (10)	−0.028 (9)	−0.043 (7)
C35	0.236 (14)	0.219 (15)	0.158 (11)	0.051 (12)	−0.025 (10)	−0.081 (11)

Geometric parameters (Å, º) top

O1—C2	1.415 (6)	C17—H17A	0.960
O1—C5	1.442 (6)	C17—H17B	0.960
C2—O11	1.403 (6)	C17—H17C	0.960
C2—C3	1.504 (8)	C18—H18A	0.960
C2—H2	0.980	C18—H18B	0.960
C3—O6	1.428 (6)	C18—H18C	0.960
C3—C4	1.542 (7)	C19—O20	1.414 (7)
C3—H3	0.980	C19—C27	1.552 (9)
C4—O8	1.419 (6)	C19—H19	0.980
C4—C5	1.523 (8)	O20—C21	1.456 (8)
C4—H4	0.980	C21—O26	1.403 (9)
C5—C19	1.499 (7)	C21—C22	1.488 (11)
C5—H5	0.980	C21—H21	0.980
O6—C7	1.401 (7)	C22—C23	1.517 (11)
C7—O8	1.410 (6)	C22—H22A	0.970
C7—C10	1.438 (10)	C22—H22B	0.970
C7—C9	1.511 (11)	C23—C24	1.485 (14)
C9—H9A	0.960	C23—H23A	0.970
C9—H9B	0.960	C23—H23B	0.970
C9—H9C	0.960	C24—C25	1.539 (15)
C10—H10A	0.960	C24—H24A	0.970
C10—H10B	0.960	C24—H24B	0.970
C10—H10C	0.960	C25—O26	1.429 (9)
O11—Si12	1.655 (4)	C25—H25A	0.970
Si12—C13	1.849 (9)	C25—H25B	0.970
Si12—C15	1.856 (7)	C27—C31	1.486 (12)
Si12—C14	1.871 (8)	C27—N28	1.510 (8)
C13—H13A	0.960	C27—H27	0.980
C13—H13B	0.960	N28—O29	1.188 (7)
C13—H13C	0.960	N28—O30	1.217 (7)
C14—H14A	0.960	C31—O32	1.184 (10)
C14—H14B	0.960	C31—O33	1.323 (9)
C14—H14C	0.960	O33—C34	1.487 (12)
C15—C17	1.511 (10)	C34—C35	1.327 (15)
C15—C16	1.521 (13)	C34—H34A	0.970
C15—C18	1.545 (12)	C34—H34B	0.970
C16—H16A	0.960	C35—H35A	0.960
C16—H16B	0.960	C35—H35B	0.960
C16—H16C	0.960	C35—H35C	0.960

C2—O1—C5	105.2 (4)	C15—C17—H17A	109.5
O11—C2—O1	110.1 (4)	C15—C17—H17B	109.5
O11—C2—C3	108.6 (4)	H17A—C17—H17B	109.5
O1—C2—C3	104.7 (4)	C15—C17—H17C	109.5
O11—C2—H2	111.1	H17A—C17—H17C	109.5
O1—C2—H2	111.1	H17B—C17—H17C	109.5
C3—C2—H2	111.1	C15—C18—H18A	109.5
O6—C3—C2	110.1 (5)	C15—C18—H18B	109.5
O6—C3—C4	104.7 (4)	H18A—C18—H18B	109.5
C2—C3—C4	105.8 (4)	C15—C18—H18C	109.5
O6—C3—H3	111.9	H18A—C18—H18C	109.5
C2—C3—H3	111.9	H18B—C18—H18C	109.5
C4—C3—H3	111.9	O20—C19—C5	106.1 (4)
O8—C4—C5	111.6 (4)	O20—C19—C27	110.2 (4)
O8—C4—C3	104.5 (4)	C5—C19—C27	115.9 (5)
C5—C4—C3	102.0 (4)	O20—C19—H19	108.1
O8—C4—H4	112.7	C5—C19—H19	108.1
C5—C4—H4	112.7	C27—C19—H19	108.1
C3—C4—H4	112.7	C19—O20—C21	116.2 (4)
O1—C5—C19	110.4 (4)	O26—C21—O20	107.8 (7)
O1—C5—C4	104.7 (4)	O26—C21—C22	114.0 (6)
C19—C5—C4	115.1 (5)	O20—C21—C22	108.5 (5)
O1—C5—H5	108.8	O26—C21—H21	108.8
C19—C5—H5	108.8	O20—C21—H21	108.8
C4—C5—H5	108.8	C22—C21—H21	108.8
C7—O6—C3	109.9 (4)	C21—C22—C23	112.8 (8)
O6—C7—O8	107.0 (4)	C21—C22—H22A	109.0
O6—C7—C10	110.3 (7)	C23—C22—H22A	109.0
O8—C7—C10	111.3 (6)	C21—C22—H22B	109.0
O6—C7—C9	107.5 (6)	C23—C22—H22B	109.0
O8—C7—C9	108.2 (6)	H22A—C22—H22B	107.8
C10—C7—C9	112.3 (9)	C24—C23—C22	109.1 (7)
C7—O8—C4	109.8 (4)	C24—C23—H23A	109.9
C7—C9—H9A	109.5	C22—C23—H23A	109.9
C7—C9—H9B	109.5	C24—C23—H23B	109.9
H9A—C9—H9B	109.5	C22—C23—H23B	109.9
C7—C9—H9C	109.5	H23A—C23—H23B	108.3
H9A—C9—H9C	109.5	C23—C24—C25	109.5 (7)
H9B—C9—H9C	109.5	C23—C24—H24A	109.8
C7—C10—H10A	109.5	C25—C24—H24A	109.8
C7—C10—H10B	109.5	C23—C24—H24B	109.8
H10A—C10—H10B	109.5	C25—C24—H24B	109.8
C7—C10—H10C	109.5	H24A—C24—H24B	108.2
H10A—C10—H10C	109.5	O26—C25—C24	110.9 (9)
H10B—C10—H10C	109.5	O26—C25—H25A	109.5
C2—O11—Si12	126.9 (4)	C24—C25—H25A	109.5
O11—Si12—C13	109.0 (4)	O26—C25—H25B	109.5
O11—Si12—C15	106.8 (3)	C24—C25—H25B	109.5
C13—Si12—C15	112.3 (5)	H25A—C25—H25B	108.1
O11—Si12—C14	108.0 (4)	C21—O26—C25	114.6 (6)
C13—Si12—C14	110.9 (6)	C31—C27—N28	108.1 (7)
C15—Si12—C14	109.8 (4)	C31—C27—C19	116.6 (5)
Si12—C13—H13A	109.5	N28—C27—C19	111.2 (5)
Si12—C13—H13B	109.5	C31—C27—H27	106.8
H13A—C13—H13B	109.5	N28—C27—H27	106.8
Si12—C13—H13C	109.5	C19—C27—H27	106.8
H13A—C13—H13C	109.5	O29—N28—O30	122.9 (6)
H13B—C13—H13C	109.5	O29—N28—C27	120.9 (5)
Si12—C14—H14A	109.5	O30—N28—C27	116.2 (6)
Si12—C14—H14B	109.5	O32—C31—O33	124.9 (9)
H14A—C14—H14B	109.5	O32—C31—C27	124.9 (8)
Si12—C14—H14C	109.5	O33—C31—C27	110.1 (8)
H14A—C14—H14C	109.5	C31—O33—C34	115.2 (8)
H14B—C14—H14C	109.5	C35—C34—O33	111.0 (12)
C17—C15—C16	112.5 (9)	C35—C34—H34A	109.4
C17—C15—C18	108.3 (8)	O33—C34—H34A	109.4
C16—C15—C18	107.3 (8)	C35—C34—H34B	109.4
C17—C15—Si12	109.8 (5)	O33—C34—H34B	109.4
C16—C15—Si12	109.0 (6)	H34A—C34—H34B	108.0
C18—C15—Si12	109.9 (7)	C34—C35—H35A	109.5
C15—C16—H16A	109.5	C34—C35—H35B	109.5
C15—C16—H16B	109.5	H35A—C35—H35B	109.5
H16A—C16—H16B	109.5	C34—C35—H35C	109.5
C15—C16—H16C	109.5	H35A—C35—H35C	109.5
H16A—C16—H16C	109.5	H35B—C35—H35C	109.5
H16B—C16—H16C	109.5

C5—O1—C2—O11	76.7 (5)	C14—Si12—C15—C16	−53.3 (8)
C5—O1—C2—C3	−39.8 (5)	O11—Si12—C15—C18	−179.2 (6)
O11—C2—C3—O6	151.5 (4)	C13—Si12—C15—C18	−59.8 (7)
O1—C2—C3—O6	−90.9 (5)	C14—Si12—C15—C18	64.0 (8)
O11—C2—C3—C4	−95.9 (5)	O1—C5—C19—O20	168.6 (4)
O1—C2—C3—C4	21.7 (5)	C4—C5—C19—O20	−73.1 (5)
O6—C3—C4—O8	3.3 (6)	O1—C5—C19—C27	45.9 (6)
C2—C3—C4—O8	−113.0 (5)	C4—C5—C19—C27	164.2 (4)
O6—C3—C4—C5	119.7 (4)	C5—C19—O20—C21	127.8 (5)
C2—C3—C4—C5	3.3 (5)	C27—C19—O20—C21	−105.9 (6)
C2—O1—C5—C19	166.9 (4)	C19—O20—C21—O26	71.9 (6)
C2—O1—C5—C4	42.4 (5)	C19—O20—C21—C22	−164.1 (5)
O8—C4—C5—O1	84.2 (5)	O26—C21—C22—C23	48.8 (9)
C3—C4—C5—O1	−26.8 (5)	O20—C21—C22—C23	−71.3 (8)
O8—C4—C5—C19	−37.1 (6)	C21—C22—C23—C24	−52.3 (11)
C3—C4—C5—C19	−148.2 (4)	C22—C23—C24—C25	56.2 (11)
C2—C3—O6—C7	122.7 (5)	C23—C24—C25—O26	−58.1 (11)
C4—C3—O6—C7	9.4 (6)	O20—C21—O26—C25	69.9 (8)
C3—O6—C7—O8	−18.8 (6)	C22—C21—O26—C25	−50.6 (10)
C3—O6—C7—C10	−140.0 (7)	C24—C25—O26—C21	54.9 (10)
C3—O6—C7—C9	97.3 (6)	O20—C19—C27—C31	179.8 (5)
O6—C7—O8—C4	21.1 (7)	C5—C19—C27—C31	−59.7 (7)
C10—C7—O8—C4	141.7 (8)	O20—C19—C27—N28	−55.6 (6)
C9—C7—O8—C4	−94.4 (7)	C5—C19—C27—N28	64.9 (7)
C5—C4—O8—C7	−124.3 (5)	C31—C27—N28—O29	79.4 (9)
C3—C4—O8—C7	−14.8 (6)	C19—C27—N28—O29	−49.8 (10)
O1—C2—O11—Si12	82.7 (5)	C31—C27—N28—O30	−98.5 (9)
C3—C2—O11—Si12	−163.2 (4)	C19—C27—N28—O30	132.2 (8)
C2—O11—Si12—C13	−19.6 (6)	N28—C27—C31—O32	3.7 (10)
C2—O11—Si12—C15	101.9 (5)	C19—C27—C31—O32	129.9 (8)
C2—O11—Si12—C14	−140.2 (5)	N28—C27—C31—O33	179.9 (5)
O11—Si12—C15—C17	−60.2 (9)	C19—C27—C31—O33	−54.0 (7)
C13—Si12—C15—C17	59.2 (9)	O32—C31—O33—C34	−7.5 (12)
C14—Si12—C15—C17	−177.0 (9)	C27—C31—O33—C34	176.4 (8)
O11—Si12—C15—C16	63.5 (6)	C31—O33—C34—C35	−170.2 (11)
C13—Si12—C15—C16	−177.1 (7)

Experimental details

Crystal data
Chemical formula	C₂₃H₄₁NO₁₀Si
M_r	519.66
Crystal system, space group	Orthorhombic, P2₁2₁2₁
Temperature (K)	293
a, b, c (Å)	15.593 (3), 9.563 (4), 19.690 (3)
V (Å³)	2935.9 (15)
Z	4
Radiation type	Cu Kα
µ (mm⁻¹)	1.13
Crystal size (mm)	0.48 × 0.40 × 0.32

Data collection
Diffractometer	Enraf–Nonius TurboCAD-4 diffractometer
Absorption correction	ψ scan (North et al., 1968)
T_min, T_max	0.614, 0.714
No. of measured, independent and observed [I > 2σ(I)] reflections	6473, 5898, 3434
R_int	0.037
(sin θ/λ)_max (Å⁻¹)	0.621

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.066, 0.264, 1.11
No. of reflections	5898
No. of parameters	325
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.22, −0.27
Absolute structure	Flack (1983), 2569 Friedel pairs
Absolute structure parameter	0.04 (8)

Computer programs: CAD-4 EXPRESS (Enraf–Nonius, 1994), XCAD4 (Harms & Wocadlo, 1995), SIR97 (Altomare et al., 1999), SHELXL97 (Sheldrick, 2008), ORTEP-3 for Windows (Farrugia, 1997), WinGX (Farrugia, 1999).

Acknowledgements

We gratefully acknowledge the Spanish Education Secretary and the Xunta de Galicia for financial support and the Spanish Education Secretary for a grant to RGS. Intensity measurements were performed at the Unidade de Raios X, RIAIDT, University of Santiago de Compostela.

References

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