2-[2-(Trimethyl­silyl)eth­yl]isoindoline-1,3-dione

Guzei, I.A.; Spencer, L.C.; Zakai, U.I.

doi:10.1107/S1600536809054105

organic compounds

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ISSN: 2056-9890

Volume 66| Part 1| January 2010| Pages o223-o224

doi:10.1107/S1600536809054105

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2-[2-(Trimethylsilyl)ethyl]isoindoline-1,3-dione

Ilia A. Guzei,^a ^* Lara C. Spencer ^a and Uzma I. Zakai ^a

^aDepartment of Chemistry, University of Wisconsin–Madison, 1101 University Ave, Madison, Wisconsin 53706, USA
^*Correspondence e-mail: iguzei@chem.wisc.edu

(Received 24 November 2009; accepted 15 December 2009; online 24 December 2009)

In the course of our studies of silicon-containing anticancer compounds, the title compound, C₁₃H₁₇NO₂Si, was synthesized. The geometrical parameters including the geometry about the Si atom are typical. The molecules form dimers via a weak C—H⋯O interaction described by the graph set R₂²(10). The dimers are assembled in rows stacked in the crystallographic b-axis direction via π–π interactions with a 3.332 (3) Å separation between the rows.

Related literature

For literature related to drug design see: Bains & Tacke (2003 ); Bikzhanova et al. (2007 ); Franz (2007 ); Franz et al. (2007 ); Gately & West (2007 ); Guzei,, Spencer, Zakai & Lynch (2010 ); Guzei, Spencer & Zakai (2010 ); Lee et al. (1993 , 1996 ); Sen & Roach (1995 ); Showell & Mills (2003 ); Tacke & Zilch (1986 ); Tsuge et al. (1985 ); Yoon et al. (1991 , 1992 , 1997 ). For a description of the Cambridge Structural Database, see: Allen (2002 ). Bond distances and angles were confirmed to be typical by a Mogul structural check (Bruno et al., 2002 ). For graph-set notation, see: Grell et al. (1999 ).

Experimental

Crystal data

C₁₃H₁₇NO₂Si
M_r = 247.37
Monoclinic, P 2₁ /n
a = 11.562 (5) Å
b = 6.411 (2) Å
c = 19.445 (8) Å
β = 95.176 (14)°
V = 1435.5 (10) Å³
Z = 4
Mo Kα radiation
μ = 0.16 mm⁻¹
T = 300 K
0.89 × 0.40 × 0.30 mm

Data collection

Bruker SMART X2S diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2009 ) T_min = 0.875, T_max = 0.955
9164 measured reflections
2701 independent reflections
1750 reflections with I > 2σ(I)
R_int = 0.036

Refinement

R[F² > 2σ(F²)] = 0.044
wR(F²) = 0.151
S = 0.99
2701 reflections
157 parameters
H-atom parameters constrained
Δρ_max = 0.15 e Å⁻³
Δρ_min = −0.16 e Å⁻³

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C11—H11⋯O2ⁱ	0.93	2.57	3.443 (4)	156
Symmetry code: (i) -x+1, -y+2, -z+1.

Data collection: APEX2 and GIS (Bruker, 2009); cell refinement: SAINT (Bruker, 2009); data reduction: SAINT; program(s) used to solve structure: SHELXTL (Sheldrick, 2008 ); program(s) used to refine structure: SHELXTL, OLEX2 (Dolomanov et al., 2009 ) and FCF_filter (Guzei, 2007 ); molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL, modiCIFer (Guzei, 2007) and publCIF (Westrip, 2010 ).

Supporting information

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536809054105/zs2025sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536809054105/zs2025Isup2.hkl

checkCIF report

Comment top

Sila phthalimides are important intermediates in photochemistry (Lee et al., 1993, 1996; Yoon et al., 1997, 1992, 1991) and organic synthesis (Bikzhanova et al., 2007; Tsuge et al., 1985). We have used methods of organosilicon chemistry (Franz, 2007; Franz et al., 2007; Gately & West, 2007; Tacke & Zilch, 1986; Showell & Mills, 2003) to prepare an array of substituted sila amines (Bikzhanova et al., 2007) and to fine-tune the properties of pharmocological drugs (Bains & Tacke, 2003). Sila phthalimides can be obtained from the respective chlorosilanes (Tsuge et al., 1985) or from alcohols by means of the Misunubu reaction (Sen & Roach, 1995) as in the present case. During our research toward silicon-containing anti-cancer drugs the title compound, (I), was isolated and characterized.

The bond distances and angles of (I) are typical as confirmed by the Mogul structural check (Bruno et al., 2002), and agree well with those for the related compounds 2-(3-(methyldiphenylsilyl)propyl)isoindoline-1,3-dione (Guzei, Spencer, Zakai & Lynch, 2010) and 2-(((4-methoxyphenyl)dimethylsilyl)methyl)isoindoline-1,3-dione (Guzei, Spencer & Zakai, 2010). Specifically, the average Si—C distances of 1.867 (3) Å for compound (I) are statistically similar to the 1.88 (3) Å average for 83 related compounds in the Cambridge Structural Database (Version 1.11, September 2009 release; Allen, 2002). The Si atom has a distorted tetrahedral geometry with angles ranging from 107.87 (11)° to 110.45 (11) °. The phthalate entity is expectedly planar within 0.0083 Å.

The molecules form dimers via a weak C11—H11···O2 interaction with a distance of 3.443 (4) Å and an angle of 155°. The pattern formed can be described in graph set notation as R₂²(10) (Grell et. al., 1999). The dimers are assembled into rows via weak π-π interactions with a distance of 3.366 (5) Å between atoms C13 in separate dimers. The rows are stacked in the crystallographic b direction.

Related literature top

For literature related to drug design see: Bains & Tacke (2003); Bikzhanova et al. (2007); Franz (2007); Franz et al. (2007); Gately & West (2007); Guzei, Spencer, Zakai & Lynch (2010); Guzei, Spencer & Zakai (2010); Lee et al. (1993, 1996); Sen & Roach (1995); Showell & Mills (2003); Tacke & Zilch (1986); Tsuge et al. (1985); Yoon et al. (1991, 1992, 1997). For a description of the Cambridge Structural Database, see: Allen (2002). Bond distances and angles were confirmed to be typical by a Mogul structural check (Bruno et al., 2002). For graph-set notation, see: Grell et al. (1999).

Experimental top

The title compound was obtained via a Mitsunubu reaction as described by Sen and co-workers (Sen & Roach, 1995). To a pre-dried 100 ml round bottom flask was added 2-(trimethylsilyl)ethanol (319 mg, 2.7 mmol). Additionally, potassium phthalimide (512 mg, 3.48 mmol) and triphenyl phosphine (913, 3.48 mmol) were added to the reaction flask. The flask was sealed with a rubber septum, evacuated, and then filled with an inert atmosphere (nitrogen). Subsequently, 30 ml of freshly distilled THF was added to the round bottom flask. In the dark, the flask was then wrapped with aluminium foil and diisopropyl azodicarboxylate (DIAD) was slowly syringed into the reaction flask. This mixture was allowed to stir at room temperature for four hours. Three ml of water was slowly injected into the reaction mixture, and the given suspension was allowed to stir for a few more minutes. The aluminium foil covering the reaction flask was removed and its contents were poured into an extraction flask. The aqueous phase was extracted 3–5 times with hexane and the resultant organic extracts were dried with MgSO₄ and filtered. The filtrate was mixed with silica gel and this slurry was dried under reduced pressure. The dry powder was loaded onto a pre-dry packed silica gel column and eluted with a gradient column. The desired material was collected using a 8:2 hexane:ethyl acetate mixture. The compound of interest was dried under reduced pressure and recrystallized from dichloromethane to afford lustrous white needles (0.35 g, 1.41 mmol, 52% yield) for X-ray crystallography. Manipulation of air and moisture sensitive compounds was performed using standard high-vacuum line techniques. All solvents and reagents were obtained from Aldrich. 2-(trimethylsilyl)ethanol was purchased from Gelest. ¹H NMR spectra were obtained on a Varian Unity 500 spectrometer, ¹³C {H} NMR spectra were obtained on a Varian 500 spectrometer operating at 125 MHz, ²⁹Si {H} NMR spectra were obtained on a Varian Unity spectrometer operating at 99 MHz. EI Mass spectra were determined on a Waters (Micromass) AutoSpec mass spectrometer. Melting points were determined on a Mel-Temp Laboratory Device. mp: 48–50°; ¹H NMR (500 MHz, CDCl₃) δ 0.04 (s, 9H, Si(Me₃)₃), 0.98 (m, 2H, CH₂), 3.69 (m, 2H, CH₂), 7.66 (dd, J=5.48, 3.01 Hz, 2H, ArH), 7.79 (dd, J=5.42, 3.06 Hz, 2H, ArH); ¹³C NMR (125 MHz, CDCl₃) δ -1.8 (SiMe), 17.0 (CH₂), 34.4 (CH₂), 123.0 (CH), 132.3 (CH), 133.7 (CH), 168.2 (CO); ²⁹Si NMR (99 MHz, CDCl₃) 0.01 (Si(Me₃)₃); MS (EI⁺) m/z (rel. intensity %) 247 (M⁺, 23), 246 (M-1, 100), 232 (50), 204 (75), 160 (26), 130 (55), 91 (49), 73 (39); HRMS (EI⁺): calcd. for C₁₃H₁₇NO₂Si (M⁺) 247.1024, found (M-1)⁺ 246.0945.

Computing details top

Data collection: GIS (Bruker, 2009); cell refinement: SAINT (Bruker, 2009); data reduction: SAINT (Bruker, 2009); program(s) used to solve structure: SHELXTL (Sheldrick, 2008); program(s) used to refine structure: SHELXTL (Sheldrick, 2008), OLEX2 (Dolomanov et al., 2009) and FCF_filter (Guzei, 2007); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008), modiCIFer (Guzei, 2007) and publCIF (Westrip, 2010).

Figures top

Fig. 1. Molecular structure of (I). The thermal ellipsoids are shown at 30% probability level.

2-[2-(Trimethylsilyl)ethyl]isoindoline-1,3-dione top

Crystal data top

C₁₃H₁₇NO₂Si	F(000) = 528
M_r = 247.37	D_x = 1.145 Mg m⁻³
Monoclinic, P2₁/n	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2yn	Cell parameters from 2755 reflections
a = 11.562 (5) Å	θ = 3.4–23.7°
b = 6.411 (2) Å	µ = 0.16 mm⁻¹
c = 19.445 (8) Å	T = 300 K
β = 95.176 (14)°	Needle, colourless
V = 1435.5 (10) Å³	0.89 × 0.40 × 0.30 mm
Z = 4

Data collection top

Bruker SMART X2S diffractometer	2701 independent reflections
Radiation source: micro-focus sealed tube	1750 reflections with I > 2σ(I)
Doubly curved silicon crystal monochromator	R_int = 0.036
ω scans	θ_max = 25.7°, θ_min = 3.4°
Absorption correction: multi-scan (SADABS; Bruker, 2009)	h = −14→14
T_min = 0.875, T_max = 0.955	k = −7→7
9164 measured reflections	l = −23→23

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)] = 0.044	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.151	H-atom parameters constrained
S = 0.99	w = 1/[σ²(F_o²) + (0.0922P)² + 0.0229P] where P = (F_o² + 2F_c²)/3
2701 reflections	(Δ/σ)_max = 0.010
157 parameters	Δρ_max = 0.15 e Å⁻³
0 restraints	Δρ_min = −0.16 e Å⁻³

Crystal data top

C₁₃H₁₇NO₂Si	V = 1435.5 (10) Å³
M_r = 247.37	Z = 4
Monoclinic, P2₁/n	Mo Kα radiation
a = 11.562 (5) Å	µ = 0.16 mm⁻¹
b = 6.411 (2) Å	T = 300 K
c = 19.445 (8) Å	0.89 × 0.40 × 0.30 mm
β = 95.176 (14)°

Data collection top

Bruker SMART X2S diffractometer	2701 independent reflections
Absorption correction: multi-scan (SADABS; Bruker, 2009)	1750 reflections with I > 2σ(I)
T_min = 0.875, T_max = 0.955	R_int = 0.036
9164 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.044	0 restraints
wR(F²) = 0.151	H-atom parameters constrained
S = 0.99	Δρ_max = 0.15 e Å⁻³
2701 reflections	Δρ_min = −0.16 e Å⁻³
157 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
Si1	0.90115 (5)	0.20211 (9)	0.38252 (3)	0.0610 (3)
O1	0.75423 (19)	0.2215 (3)	0.61648 (12)	0.1052 (7)
O2	0.60178 (16)	0.7082 (3)	0.46280 (10)	0.0929 (6)
N1	0.68492 (15)	0.4340 (3)	0.52646 (10)	0.0686 (5)
C1	0.8769 (3)	−0.0839 (4)	0.38950 (16)	0.0987 (9)
H1A	0.9213	−0.1366	0.4299	0.148*
H1B	0.9009	−0.1522	0.3492	0.148*
H1C	0.7959	−0.1103	0.3930	0.148*
C2	1.0592 (2)	0.2585 (5)	0.37947 (16)	0.1010 (9)
H2A	1.1015	0.2083	0.4209	0.152*
H2B	1.0705	0.4063	0.3757	0.152*
H2C	1.0869	0.1900	0.3402	0.152*
C3	0.8170 (3)	0.3029 (5)	0.30296 (15)	0.1078 (10)
H3A	0.8418	0.2326	0.2632	0.162*
H3B	0.8302	0.4500	0.2989	0.162*
H3C	0.7357	0.2778	0.3058	0.162*
C4	0.85121 (18)	0.3403 (3)	0.45914 (11)	0.0615 (6)
H4A	0.8976	0.2924	0.5001	0.074*
H4B	0.8659	0.4883	0.4543	0.074*
C5	0.72357 (19)	0.3103 (4)	0.47001 (13)	0.0773 (7)
H5A	0.6770	0.3469	0.4277	0.093*
H5B	0.7100	0.1640	0.4792	0.093*
C6	0.7031 (2)	0.3775 (4)	0.59582 (14)	0.0758 (7)
C7	0.6491 (2)	0.5451 (4)	0.63477 (13)	0.0724 (6)
C8	0.6418 (3)	0.5693 (6)	0.70431 (16)	0.0995 (9)
H8	0.6728	0.4707	0.7359	0.119*
C9	0.5867 (3)	0.7459 (7)	0.72558 (18)	0.1135 (11)
H9	0.5795	0.7658	0.7724	0.136*
C10	0.5424 (3)	0.8922 (6)	0.67926 (19)	0.1061 (10)
H10	0.5059	1.0092	0.6955	0.127*
C11	0.5502 (2)	0.8714 (4)	0.60893 (15)	0.0847 (8)
H11	0.5206	0.9715	0.5775	0.102*
C12	0.60455 (18)	0.6934 (4)	0.58821 (12)	0.0659 (6)
C13	0.62725 (19)	0.6246 (4)	0.51808 (13)	0.0679 (6)

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Si1	0.0681 (4)	0.0500 (4)	0.0653 (4)	−0.0086 (3)	0.0081 (3)	−0.0030 (3)
O1	0.1094 (16)	0.0863 (13)	0.1218 (16)	0.0091 (12)	0.0198 (13)	0.0246 (12)
O2	0.0852 (13)	0.1100 (14)	0.0822 (13)	0.0171 (11)	−0.0001 (10)	0.0038 (10)
N1	0.0528 (11)	0.0727 (12)	0.0818 (13)	−0.0037 (9)	0.0134 (9)	−0.0067 (10)
C1	0.119 (2)	0.0547 (15)	0.125 (2)	−0.0060 (14)	0.0245 (19)	−0.0052 (15)
C2	0.0817 (19)	0.113 (2)	0.113 (2)	−0.0169 (17)	0.0352 (17)	−0.0301 (18)
C3	0.140 (3)	0.100 (2)	0.0790 (18)	−0.0160 (19)	−0.0120 (18)	0.0127 (15)
C4	0.0537 (13)	0.0573 (12)	0.0731 (14)	−0.0078 (10)	0.0040 (10)	−0.0068 (10)
C5	0.0557 (14)	0.0794 (16)	0.0971 (18)	−0.0096 (12)	0.0096 (13)	−0.0228 (13)
C6	0.0624 (15)	0.0761 (16)	0.0902 (18)	−0.0133 (13)	0.0135 (12)	0.0076 (14)
C7	0.0562 (13)	0.0845 (16)	0.0787 (16)	−0.0124 (12)	0.0180 (12)	0.0012 (13)
C8	0.088 (2)	0.129 (3)	0.0849 (19)	−0.0080 (18)	0.0235 (15)	0.0079 (18)
C9	0.091 (2)	0.167 (3)	0.086 (2)	−0.014 (2)	0.0268 (18)	−0.025 (2)
C10	0.078 (2)	0.124 (3)	0.120 (3)	−0.0098 (18)	0.0273 (19)	−0.045 (2)
C11	0.0559 (14)	0.0910 (18)	0.108 (2)	−0.0047 (13)	0.0119 (13)	−0.0201 (16)
C12	0.0427 (11)	0.0765 (15)	0.0791 (15)	−0.0121 (11)	0.0095 (10)	−0.0134 (13)
C13	0.0469 (12)	0.0777 (15)	0.0789 (16)	−0.0061 (11)	0.0040 (11)	−0.0031 (13)

Geometric parameters (Å, º) top

Si1—C1	1.862 (2)	C4—C5	1.522 (3)
Si1—C2	1.869 (3)	C4—H4A	0.9700
Si1—C4	1.869 (2)	C4—H4B	0.9700
Si1—C3	1.867 (3)	C5—H5A	0.9700
O1—C6	1.212 (3)	C5—H5B	0.9700
O2—C13	1.213 (3)	C6—C7	1.484 (4)
N1—C6	1.394 (3)	C7—C8	1.371 (4)
N1—C13	1.395 (3)	C7—C12	1.380 (3)
N1—C5	1.457 (3)	C8—C9	1.381 (5)
C1—H1A	0.9600	C8—H8	0.9300
C1—H1B	0.9600	C9—C10	1.367 (5)
C1—H1C	0.9600	C9—H9	0.9300
C2—H2A	0.9600	C10—C11	1.385 (4)
C2—H2B	0.9600	C10—H10	0.9300
C2—H2C	0.9600	C11—C12	1.380 (3)
C3—H3A	0.9600	C11—H11	0.9300
C3—H3B	0.9600	C12—C13	1.479 (3)
C3—H3C	0.9600

C1—Si1—C2	110.31 (14)	H4A—C4—H4B	107.5
C1—Si1—C4	110.45 (11)	N1—C5—C4	113.77 (18)
C2—Si1—C4	107.87 (11)	N1—C5—H5A	108.8
C1—Si1—C3	109.30 (14)	C4—C5—H5A	108.8
C2—Si1—C3	110.16 (15)	N1—C5—H5B	108.8
C4—Si1—C3	108.73 (14)	C4—C5—H5B	108.8
C6—N1—C13	111.7 (2)	H5A—C5—H5B	107.7
C6—N1—C5	123.9 (2)	O1—C6—N1	124.2 (3)
C13—N1—C5	124.4 (2)	O1—C6—C7	130.1 (3)
Si1—C1—H1A	109.5	N1—C6—C7	105.8 (2)
Si1—C1—H1B	109.5	C8—C7—C12	121.1 (2)
H1A—C1—H1B	109.5	C8—C7—C6	130.6 (3)
Si1—C1—H1C	109.5	C12—C7—C6	108.3 (2)
H1A—C1—H1C	109.5	C7—C8—C9	117.3 (3)
H1B—C1—H1C	109.5	C7—C8—H8	121.3
Si1—C2—H2A	109.5	C9—C8—H8	121.3
Si1—C2—H2B	109.5	C10—C9—C8	121.4 (3)
H2A—C2—H2B	109.5	C10—C9—H9	119.3
Si1—C2—H2C	109.5	C8—C9—H9	119.3
H2A—C2—H2C	109.5	C9—C10—C11	122.1 (3)
H2B—C2—H2C	109.5	C9—C10—H10	119.0
Si1—C3—H3A	109.5	C11—C10—H10	119.0
Si1—C3—H3B	109.5	C10—C11—C12	116.1 (3)
H3A—C3—H3B	109.5	C10—C11—H11	122.0
Si1—C3—H3C	109.5	C12—C11—H11	122.0
H3A—C3—H3C	109.5	C11—C12—C7	122.1 (2)
H3B—C3—H3C	109.5	C11—C12—C13	129.7 (2)
C5—C4—Si1	115.09 (15)	C7—C12—C13	108.2 (2)
C5—C4—H4A	108.5	O2—C13—N1	124.5 (2)
Si1—C4—H4A	108.5	O2—C13—C12	129.5 (2)
C5—C4—H4B	108.5	N1—C13—C12	106.0 (2)
Si1—C4—H4B	108.5

C1—Si1—C4—C5	−59.0 (2)	C8—C9—C10—C11	0.1 (5)
C2—Si1—C4—C5	−179.61 (18)	C9—C10—C11—C12	0.5 (4)
C3—Si1—C4—C5	60.9 (2)	C10—C11—C12—C7	−0.3 (4)
C6—N1—C5—C4	−80.8 (3)	C10—C11—C12—C13	−179.8 (2)
C13—N1—C5—C4	98.0 (3)	C8—C7—C12—C11	−0.4 (3)
Si1—C4—C5—N1	−174.99 (17)	C6—C7—C12—C11	−178.9 (2)
C13—N1—C6—O1	−177.9 (2)	C8—C7—C12—C13	179.2 (2)
C5—N1—C6—O1	1.0 (4)	C6—C7—C12—C13	0.7 (2)
C13—N1—C6—C7	1.7 (2)	C6—N1—C13—O2	179.6 (2)
C5—N1—C6—C7	−179.43 (18)	C5—N1—C13—O2	0.7 (3)
O1—C6—C7—C8	−0.2 (5)	C6—N1—C13—C12	−1.3 (2)
N1—C6—C7—C8	−179.7 (2)	C5—N1—C13—C12	179.83 (18)
O1—C6—C7—C12	178.1 (3)	C11—C12—C13—O2	−1.0 (4)
N1—C6—C7—C12	−1.4 (2)	C7—C12—C13—O2	179.4 (2)
C12—C7—C8—C9	1.0 (4)	C11—C12—C13—N1	179.9 (2)
C6—C7—C8—C9	179.1 (3)	C7—C12—C13—N1	0.3 (2)
C7—C8—C9—C10	−0.8 (5)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
C11—H11···O2ⁱ	0.93	2.57	3.443 (4)	156

Symmetry code: (i) −x+1, −y+2, −z+1.

Experimental details

Crystal data
Chemical formula	C₁₃H₁₇NO₂Si
M_r	247.37
Crystal system, space group	Monoclinic, P2₁/n
Temperature (K)	300
a, b, c (Å)	11.562 (5), 6.411 (2), 19.445 (8)
β (°)	95.176 (14)
V (Å³)	1435.5 (10)
Z	4
Radiation type	Mo Kα
µ (mm⁻¹)	0.16
Crystal size (mm)	0.89 × 0.40 × 0.30

Data collection
Diffractometer	Bruker SMART X2S diffractometer
Absorption correction	Multi-scan (SADABS; Bruker, 2009)
T_min, T_max	0.875, 0.955
No. of measured, independent and observed [I > 2σ(I)] reflections	9164, 2701, 1750
R_int	0.036
(sin θ/λ)_max (Å⁻¹)	0.610

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.044, 0.151, 0.99
No. of reflections	2701
No. of parameters	157
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.15, −0.16

Computer programs: GIS (Bruker, 2009), SAINT (Bruker, 2009), SHELXTL (Sheldrick, 2008), OLEX2 (Dolomanov et al., 2009) and FCF_filter (Guzei, 2007), SHELXTL (Sheldrick, 2008), modiCIFer (Guzei, 2007) and publCIF (Westrip, 2010).

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
C11—H11···O2ⁱ	0.93	2.57	3.443 (4)	155.5

Symmetry code: (i) −x+1, −y+2, −z+1.

Acknowledgements

We thank Dr N. J. Hill (UW-Madison) for acquiring the data and Professor R. West (UW-Madison) for his support. We gratefully acknowledge Bruker sponsorship of this publication and also acknowledge grants NIH 1 S10 RRO 8389–01 and NSF CHE-9629688 for providing NMR spectrometers, and grant NSF CHE-9304546 for providing the mass spectrometer for this work.

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