(2S)-Ethyl 2-[(Ss)-benzyl­sulfinyl­amino]-3,3-dimethylbutanoate

Zheng, W.; Sun, X.; Sun, J.; Wei, B.-G.

doi:10.1107/S1600536808028717

organic compounds

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ISSN: 2056-9890

Volume 64| Part 10| October 2008| Page o1933

doi:10.1107/S1600536808028717

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(2S)-Ethyl 2-[(S_s)-benzylsulfinylamino]-3,3-dimethylbutanoate

Wei Zheng,^a Xun Sun,^a ^* Jie Sun ^b and Bang-Guo Wei ^c

^aDepartment of Chemistry of Natural Drugs, School of Pharmacy, Fudan University, Shanghai 200032, People's Republic of China, ^bShanghai Institute of Organic Chemistry, Shanghai 200032, People's Republic of China, and ^cDepartment of Chemistry, Fudan University, Shanghai 200032, People's Republic of China
^*Correspondence e-mail: sunxunf@shmu.edu.cn

(Received 30 July 2008; accepted 8 September 2008; online 13 September 2008)

The title compound, C₁₅H₂₃NO₃S, is an unexpected 1,3-migration product in the addition of benzylzinc bromide to N-tert-butanesulfinyl iminoacetate. In the crystal structure, molecules are linked by N—H⋯O hydrogen bonds and weak C—H⋯O hydrogen bonds.

Related literature

For general background, see: Ellman et al. (2002 ); Lin et al. (2008 ); Daniel & Stockman (2006 ). For the synthesis of the titled compound, see: Sun et al. (2008 ).

Experimental

Crystal data

C₁₅H₂₃NO₃S
M_r = 297.40
Monoclinic, P 2₁
a = 11.166 (2) Å
b = 7.1917 (14) Å
c = 11.460 (2) Å
β = 115.473 (3)°
V = 830.8 (3) Å³
Z = 2
Mo Kα radiation
μ = 0.20 mm⁻¹
T = 293 (2) K
0.49 × 0.41 × 0.17 mm

Data collection

Bruker SMART APEX CCD area-detector diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2001 ) T_min = 0.908, T_max = 0.967
4782 measured reflections
3221 independent reflections
2661 reflections with I > 2σ(I)
R_int = 0.120

Refinement

R[F² > 2σ(F²)] = 0.054
wR(F²) = 0.134
S = 0.97
3221 reflections
189 parameters
2 restraints
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.43 e Å⁻³
Δρ_min = −0.23 e Å⁻³
Absolute structure: Flack (1983 ), 1295 Friedel pairs
Flack parameter: −0.09 (11)

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C7—H7B⋯O1	0.96	2.61	3.234 (5)	123
C9—H9B⋯O3ⁱ	0.97	2.48	3.296 (5)	142
N1—H1A⋯O3ⁱ	0.859 (17)	2.13 (2)	2.932 (3)	156 (3)
Symmetry code: (i) $[-x, y-{\script{1\over 2}}, -z+1]$ .

Data collection: SMART (Bruker, 2001); cell refinement: SAINT (Bruker, 2001); data reduction: SAINT; 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: SHELXTL.

Supporting information

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536808028717/zl2133sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536808028717/zl2133Isup2.hkl

checkCIF report

Comment top

N-tert-Butanesulfinylamide has received considerable attention in the auxiliary-aided asymmetric synthesis of a broad range of chiral amines (Ellman et al., 2002; Stockman et al., 2006; Lin et al., 2008). In our research on the asymmetric addition of organozinc reagents to chiral N-tert-butanesulfinyl iminoacetates, an unexpected rearrangement product was obtained instead of the desired nucleophilic addition product. The structure of the compound obtained by 1,3-migration of the tert-butyl group was determined to be (2S)-ethyl 3,3-dimethyl-2-((S_s)-benzylsulfinylamino)butanoate. The reaction sequence (Sun et al., 2008) is briefly shown in Fig. 4. The absolute configuration at the sulfur atom (as determined by the Flack parameter) is S as in the starting material. The new chiral center at C1 also exhibits an S-configuration. We believe this unusual rearrangement reaction could be developed to be a novel and convenient approach to prepare tert-leucine.

The crystal packing in the title compound is stabilized by an intramolecular hydrogen interaction (C7—H7B···O1) and by two intermolecular hydrogen bonds (N1—H1A···O3ⁱ and C9—H9B···O3ⁱ, symmetry operator: (i) -x, y-1/2, -z+1) which lead to the formation of an one-dimensional hydrogen bonded chain along the b axis as shown in Fig. 3.

Related literature top

For related literature, see: Ellman et al. (2002); Lin et al. (2008); Sun et al. (2008); Daniel & Stockman (2006).

Experimental top

To a solution of ethyl N-(tert-butanesulfinyl)iminoacetate (1 mmol) and Ni(acac)₂ (10 mol%) in anhydrous THF (10 ml) was added freshly prepared benzylzinc bromide (2.5 ml, 1 M in THF) at 195 K under an argon atmosphere. Then the mixture was allowed to warm to room temperature. After stirring for another 6 h, the reaction was quenched with saturated aqueous NH₄Cl (4 ml). The mixture was extracted with EtOAc (10 ml) twice. The combined organic phases were washed with brine and dried with anhydrous Na₂SO₄. After concentrating under reduced pressure, the residue was purified by silica gel chromatography to give the title compound (yield: 47%). Suitable crystals were obtained by recrystallization from acetone (m.p. 421–423 K). [α]_D²⁵ 132.2 (c = 0.60, CHCl₃). ¹H NMR (δ, CDCl₃) 7.31-7.42 (m, 5H), 4.33 (d, J = 9.0, 1H), 4.12-4.20 (m, 2H), 4.03 (s, 2H), 3.48 (d, J = 9.0, 1H), 1.24 (t, J = 7.0, 3H), 0.83 (s, 9H). HRMS for (C₁₅H₂₃NO₃S) found 289.1469, Calcd 289.1477.

Computing details top

Data collection: SMART (Bruker, 2001); cell refinement: SMART (Bruker, 2001); data reduction: SAINT (Bruker, 2001); 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: SHELXTL (Sheldrick, 2008).

Figures top

	Fig. 1. Plot of C₁₅H₂₃NO₃S with 50% probability levels. H atoms are drawn as spheres of arbitrary radius.
	Fig. 2. Hydrogen bonding in the title compound. Symmetry code: (i) -x, y-1/2, -z+1.
	Fig. 3. Molecular packing plot showing the one-dimensional polymeric chains of the title compound. Hydrogen bond interactions are shown as dashed lines.
	Fig. 4. Reaction sequence.

(2S)-Ethyl 2-[(S_s)-benzylsulfinylamino]-3,3-dimethylbutanoate top

Crystal data top

C₁₅H₂₃NO₃S	F(000) = 320
M_r = 297.40	D_x = 1.189 Mg m⁻³
Monoclinic, P2₁	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2yb	Cell parameters from 1845 reflections
a = 11.166 (2) Å	θ = 3.4–23.9°
b = 7.1917 (14) Å	µ = 0.20 mm⁻¹
c = 11.460 (2) Å	T = 293 K
β = 115.473 (3)°	Prismatic, colorless
V = 830.8 (3) Å³	0.49 × 0.41 × 0.17 mm
Z = 2

Data collection top

Bruker SMART APEX CCD area-detector diffractometer	3221 independent reflections
Radiation source: fine-focus sealed tube	2661 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.120
ϕ and ω scans	θ_max = 27.0°, θ_min = 2.0°
Absorption correction: multi-scan (SADABS; Bruker, 2001)	h = −11→14
T_min = 0.908, T_max = 0.967	k = −8→9
4782 measured reflections	l = −14→13

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)] = 0.055	H atoms treated by a mixture of independent and constrained refinement
wR(F²) = 0.134	w = 1/[σ²(F_o²) + (0.0662P)²] where P = (F_o² + 2F_c²)/3
S = 0.97	(Δ/σ)_max = 0.001
3221 reflections	Δρ_max = 0.43 e Å⁻³
189 parameters	Δρ_min = −0.23 e Å⁻³
2 restraints	Absolute structure: Flack (1983), 1295 Friedel pairs
Primary atom site location: structure-invariant direct methods	Absolute structure parameter: −0.09 (11)

Crystal data top

C₁₅H₂₃NO₃S	V = 830.8 (3) Å³
M_r = 297.40	Z = 2
Monoclinic, P2₁	Mo Kα radiation
a = 11.166 (2) Å	µ = 0.20 mm⁻¹
b = 7.1917 (14) Å	T = 293 K
c = 11.460 (2) Å	0.49 × 0.41 × 0.17 mm
β = 115.473 (3)°

Data collection top

Bruker SMART APEX CCD area-detector diffractometer	3221 independent reflections
Absorption correction: multi-scan (SADABS; Bruker, 2001)	2661 reflections with I > 2σ(I)
T_min = 0.908, T_max = 0.967	R_int = 0.120
4782 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.055	H atoms treated by a mixture of independent and constrained refinement
wR(F²) = 0.134	Δρ_max = 0.43 e Å⁻³
S = 0.97	Δρ_min = −0.23 e Å⁻³
3221 reflections	Absolute structure: Flack (1983), 1295 Friedel pairs
189 parameters	Absolute structure parameter: −0.09 (11)
2 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
S1	0.04167 (7)	0.26178 (12)	0.67424 (6)	0.0442 (2)
O1	0.3061 (3)	0.0339 (4)	0.5596 (3)	0.0741 (8)
O2	0.4124 (3)	0.2630 (5)	0.6946 (2)	0.0696 (7)
O3	0.0313 (3)	0.3869 (4)	0.5670 (2)	0.0665 (7)
N1	0.1252 (2)	0.0717 (4)	0.6804 (2)	0.0420 (6)
C1	0.2690 (3)	0.0814 (4)	0.7500 (3)	0.0397 (6)
H1	0.2901	0.1873	0.8094	0.048*
C2	0.3305 (3)	0.1206 (5)	0.6568 (3)	0.0501 (8)
C3	0.4801 (5)	0.3093 (8)	0.6131 (5)	0.0923 (17)
H3A	0.5348	0.2058	0.6108	0.111*
H3B	0.4155	0.3353	0.5255	0.111*
C4	0.5613 (6)	0.4705 (9)	0.6677 (5)	0.108 (2)
H4A	0.5056	0.5775	0.6547	0.162*
H4B	0.6189	0.4900	0.6263	0.162*
H4C	0.6136	0.4516	0.7586	0.162*
C5	0.3281 (3)	−0.0954 (5)	0.8332 (3)	0.0478 (7)
C6	0.4791 (4)	−0.0865 (6)	0.8887 (4)	0.0681 (10)
H6A	0.5167	−0.1912	0.9445	0.102*
H6B	0.5099	0.0264	0.9371	0.102*
H6C	0.5057	−0.0892	0.8194	0.102*
C7	0.2792 (4)	−0.2720 (5)	0.7539 (4)	0.0649 (10)
H7A	0.3185	−0.3781	0.8076	0.097*
H7B	0.3039	−0.2702	0.6833	0.097*
H7C	0.1844	−0.2791	0.7206	0.097*
C8	0.2833 (4)	−0.0948 (6)	0.9414 (3)	0.0653 (10)
H8A	0.1882	−0.0909	0.9048	0.098*
H8B	0.3191	0.0124	0.9952	0.098*
H8C	0.3145	−0.2055	0.9924	0.098*
C9	−0.1205 (3)	0.1504 (5)	0.6172 (3)	0.0513 (8)
H9A	−0.1880	0.2455	0.5975	0.062*
H9B	−0.1384	0.0834	0.5380	0.062*
C10	−0.1293 (3)	0.0198 (5)	0.7130 (3)	0.0494 (8)
C11	−0.1140 (4)	−0.1679 (6)	0.7036 (4)	0.0664 (10)
H11	−0.1014	−0.2145	0.6340	0.080*
C12	−0.1169 (5)	−0.2890 (6)	0.7960 (5)	0.0895 (15)
H12	−0.1062	−0.4161	0.7885	0.107*
C13	−0.1357 (5)	−0.2210 (10)	0.8991 (5)	0.0940 (15)
H13	−0.1374	−0.3023	0.9615	0.113*
C14	−0.1515 (5)	−0.0390 (8)	0.9098 (5)	0.0903 (16)
H14	−0.1651	0.0056	0.9794	0.108*
C15	−0.1479 (4)	0.0835 (6)	0.8193 (4)	0.0702 (11)
H15	−0.1579	0.2101	0.8289	0.084*
H1A	0.102 (3)	0.001 (3)	0.614 (2)	0.049 (7)*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
S1	0.0470 (4)	0.0432 (4)	0.0420 (3)	0.0052 (4)	0.0189 (3)	0.0057 (4)
O1	0.0850 (19)	0.095 (2)	0.0564 (14)	−0.0256 (17)	0.0441 (13)	−0.0240 (15)
O2	0.0750 (16)	0.0817 (16)	0.0677 (13)	−0.0294 (18)	0.0455 (12)	−0.0137 (18)
O3	0.0640 (16)	0.0639 (16)	0.0641 (15)	0.0019 (13)	0.0206 (12)	0.0255 (13)
N1	0.0404 (14)	0.0454 (15)	0.0379 (12)	−0.0008 (11)	0.0146 (11)	−0.0041 (11)
C1	0.0383 (15)	0.0425 (17)	0.0387 (14)	−0.0046 (13)	0.0168 (12)	−0.0055 (13)
C2	0.0424 (17)	0.060 (2)	0.0489 (18)	−0.0037 (16)	0.0205 (14)	−0.0013 (16)
C3	0.098 (4)	0.119 (5)	0.086 (3)	−0.040 (3)	0.065 (3)	−0.019 (3)
C4	0.105 (4)	0.132 (5)	0.112 (4)	−0.035 (4)	0.070 (3)	0.001 (3)
C5	0.0499 (18)	0.0452 (17)	0.0415 (16)	0.0018 (15)	0.0132 (13)	−0.0001 (14)
C6	0.048 (2)	0.073 (2)	0.064 (2)	0.0088 (19)	0.0065 (17)	0.002 (2)
C7	0.067 (2)	0.048 (3)	0.067 (2)	0.0015 (18)	0.0159 (17)	−0.0079 (17)
C8	0.080 (3)	0.067 (2)	0.0490 (19)	0.004 (2)	0.0276 (18)	0.0121 (18)
C9	0.0421 (17)	0.065 (2)	0.0451 (16)	0.0087 (16)	0.0174 (14)	0.0066 (15)
C10	0.0369 (17)	0.059 (2)	0.0522 (18)	−0.0030 (14)	0.0190 (14)	0.0005 (15)
C11	0.062 (2)	0.070 (3)	0.064 (2)	−0.0145 (19)	0.0243 (18)	−0.0035 (18)
C12	0.092 (4)	0.058 (3)	0.113 (4)	−0.018 (2)	0.038 (3)	0.011 (2)
C13	0.086 (3)	0.108 (4)	0.094 (3)	−0.021 (4)	0.044 (2)	0.033 (4)
C14	0.095 (4)	0.121 (5)	0.077 (3)	−0.006 (3)	0.057 (3)	0.012 (3)
C15	0.074 (3)	0.075 (3)	0.074 (2)	−0.001 (2)	0.043 (2)	−0.002 (2)

Geometric parameters (Å, º) top

S1—O3	1.487 (2)	C6—H6C	0.9600
S1—N1	1.639 (3)	C7—H7A	0.9600
S1—C9	1.824 (4)	C7—H7B	0.9600
O1—C2	1.201 (4)	C7—H7C	0.9600
O2—C2	1.316 (4)	C8—H8A	0.9600
O2—C3	1.471 (4)	C8—H8B	0.9600
N1—C1	1.455 (4)	C8—H8C	0.9600
N1—H1A	0.859 (17)	C9—C10	1.480 (5)
C1—C2	1.523 (4)	C9—H9A	0.9700
C1—C5	1.555 (4)	C9—H9B	0.9700
C1—H1	0.9800	C10—C11	1.371 (5)
C3—C4	1.439 (7)	C10—C15	1.398 (5)
C3—H3A	0.9700	C11—C12	1.382 (6)
C3—H3B	0.9700	C11—H11	0.9300
C4—H4A	0.9600	C12—C13	1.375 (7)
C4—H4B	0.9600	C12—H12	0.9300
C4—H4C	0.9600	C13—C14	1.334 (8)
C5—C7	1.520 (5)	C13—H13	0.9300
C5—C8	1.524 (5)	C14—C15	1.374 (6)
C5—C6	1.526 (5)	C14—H14	0.9300
C6—H6A	0.9600	C15—H15	0.9300
C6—H6B	0.9600

O3—S1—N1	112.37 (15)	H6A—C6—H6C	109.5
O3—S1—C9	104.90 (15)	H6B—C6—H6C	109.5
N1—S1—C9	96.19 (15)	C5—C7—H7A	109.5
C2—O2—C3	116.2 (3)	C5—C7—H7B	109.5
C1—N1—S1	117.2 (2)	H7A—C7—H7B	109.5
C1—N1—H1A	111.1 (19)	C5—C7—H7C	109.5
S1—N1—H1A	120.2 (19)	H7A—C7—H7C	109.5
N1—C1—C2	110.4 (2)	H7B—C7—H7C	109.5
N1—C1—C5	111.9 (2)	C5—C8—H8A	109.5
C2—C1—C5	112.4 (3)	C5—C8—H8B	109.5
N1—C1—H1	107.3	H8A—C8—H8B	109.5
C2—C1—H1	107.3	C5—C8—H8C	109.5
C5—C1—H1	107.3	H8A—C8—H8C	109.5
O1—C2—O2	123.9 (3)	H8B—C8—H8C	109.5
O1—C2—C1	124.3 (3)	C10—C9—S1	112.7 (2)
O2—C2—C1	111.8 (3)	C10—C9—H9A	109.1
C4—C3—O2	107.8 (4)	S1—C9—H9A	109.1
C4—C3—H3A	110.1	C10—C9—H9B	109.1
O2—C3—H3A	110.1	S1—C9—H9B	109.1
C4—C3—H3B	110.1	H9A—C9—H9B	107.8
O2—C3—H3B	110.1	C11—C10—C15	117.5 (4)
H3A—C3—H3B	108.5	C11—C10—C9	121.1 (3)
C3—C4—H4A	109.5	C15—C10—C9	121.4 (3)
C3—C4—H4B	109.5	C10—C11—C12	121.0 (4)
H4A—C4—H4B	109.5	C10—C11—H11	119.5
C3—C4—H4C	109.5	C12—C11—H11	119.5
H4A—C4—H4C	109.5	C13—C12—C11	119.8 (4)
H4B—C4—H4C	109.5	C13—C12—H12	120.1
C7—C5—C8	109.2 (3)	C11—C12—H12	120.1
C7—C5—C6	109.4 (3)	C14—C13—C12	120.2 (4)
C8—C5—C6	110.6 (3)	C14—C13—H13	119.9
C7—C5—C1	111.6 (2)	C12—C13—H13	119.9
C8—C5—C1	107.2 (3)	C13—C14—C15	120.8 (5)
C6—C5—C1	108.8 (3)	C13—C14—H14	119.6
C5—C6—H6A	109.5	C15—C14—H14	119.6
C5—C6—H6B	109.5	C14—C15—C10	120.8 (4)
H6A—C6—H6B	109.5	C14—C15—H15	119.6
C5—C6—H6C	109.5	C10—C15—H15	119.6

O3—S1—N1—C1	84.8 (2)	N1—C1—C5—C6	172.6 (3)
C9—S1—N1—C1	−166.3 (2)	C2—C1—C5—C6	47.8 (3)
S1—N1—C1—C2	−95.2 (3)	O3—S1—C9—C10	−179.6 (3)
S1—N1—C1—C5	138.8 (2)	N1—S1—C9—C10	65.2 (3)
C3—O2—C2—O1	−2.6 (6)	S1—C9—C10—C11	−99.0 (4)
C3—O2—C2—C1	178.3 (4)	S1—C9—C10—C15	78.2 (4)
N1—C1—C2—O1	−51.2 (4)	C15—C10—C11—C12	0.1 (6)
C5—C1—C2—O1	74.6 (4)	C9—C10—C11—C12	177.4 (4)
N1—C1—C2—O2	128.0 (3)	C10—C11—C12—C13	0.1 (7)
C5—C1—C2—O2	−106.3 (3)	C11—C12—C13—C14	0.2 (8)
C2—O2—C3—C4	178.3 (4)	C12—C13—C14—C15	−0.7 (9)
N1—C1—C5—C7	51.8 (3)	C13—C14—C15—C10	0.9 (7)
C2—C1—C5—C7	−73.1 (4)	C11—C10—C15—C14	−0.5 (6)
N1—C1—C5—C8	−67.8 (3)	C9—C10—C15—C14	−177.8 (4)
C2—C1—C5—C8	167.4 (3)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
C7—H7B···O1	0.96	2.61	3.234 (5)	123
C9—H9B···O3ⁱ	0.97	2.48	3.296 (5)	142
N1—H1A···O3ⁱ	0.86 (2)	2.13 (2)	2.932 (3)	156 (3)

Symmetry code: (i) −x, y−1/2, −z+1.

Experimental details

Crystal data
Chemical formula	C₁₅H₂₃NO₃S
M_r	297.40
Crystal system, space group	Monoclinic, P2₁
Temperature (K)	293
a, b, c (Å)	11.166 (2), 7.1917 (14), 11.460 (2)
β (°)	115.473 (3)
V (Å³)	830.8 (3)
Z	2
Radiation type	Mo Kα
µ (mm⁻¹)	0.20
Crystal size (mm)	0.49 × 0.41 × 0.17

Data collection
Diffractometer	Bruker SMART APEX CCD area-detector diffractometer
Absorption correction	Multi-scan (SADABS; Bruker, 2001)
T_min, T_max	0.908, 0.967
No. of measured, independent and observed [I > 2σ(I)] reflections	4782, 3221, 2661
R_int	0.120
(sin θ/λ)_max (Å⁻¹)	0.639

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.055, 0.134, 0.97
No. of reflections	3221
No. of parameters	189
No. of restraints	2
H-atom treatment	H atoms treated by a mixture of independent and constrained refinement
Δρ_max, Δρ_min (e Å⁻³)	0.43, −0.23
Absolute structure	Flack (1983), 1295 Friedel pairs
Absolute structure parameter	−0.09 (11)

Computer programs: SMART (Bruker, 2001), SMART (Bruker, 2001), SAINT (Bruker, 2001), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), SHELXTL (Sheldrick, 2008).

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
C7—H7B···O1	0.96	2.61	3.234 (5)	122.8
C9—H9B···O3ⁱ	0.97	2.48	3.296 (5)	142.2
N1—H1A···O3ⁱ	0.859 (17)	2.13 (2)	2.932 (3)	156 (3)

Symmetry code: (i) −x, y−1/2, −z+1.

Acknowledgements

The work was financially supported by the National Science Foundation of China (grant No. 20772017) and the Shanghai Municipal Committee of Science and Technology (grant No. 07DZ19713).

References

Bruker (2001). SAINT, SMART and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA. Google Scholar
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