4-Nitro­phenyl α-l-rhamnopyran­oside hemihydrate

Jianbo Zhang; Jie Fu; Xuan Chen; Yijun Gu; Jie Tang

doi:10.1107/S1600536808006387

. 2008 Mar 14;64(Pt 4):o714. doi: 10.1107/S1600536808006387

4-Nitrophenyl α-l-rhamnopyranoside hemihydrate¹

Jianbo Zhang ^a,^*, Jie Fu ^a, Xuan Chen ^a, Yijun Gu ^b, Jie Tang ^a

PMCID: PMC2960897 PMID: 21202105

Abstract

The absolute configuration of the title compound, C₁₂H₁₅NO₇·0.5H₂O, was assigned from the synthesis. There are two rhamnoside molecules and one water molecule in the asymmetric unit, displaying O—H⋯O hydrogen bonding. One of the nitro groups does not conjugate efficiently with the benzene ring.

Related literature

For related literature, see: Garegg & Norberg (1983 ▶); Garegg et al. (1978 ▶); Martearena et al. (2003 ▶); Nishio et al. (2004 ▶); Temeriusz et al. (2005 ▶); Flack (1983 ▶); Flack & Bernardinelli (2000 ▶).

Experimental

Crystal data

C₁₂H₁₅NO₇·0.5H₂O
M _r = 294.26
Monoclinic,
a = 10.6189 (10) Å
b = 6.9002 (7) Å
c = 18.9318 (18) Å
β = 100.909 (2)°
V = 1362.1 (2) Å³
Z = 4
Mo Kα radiation
μ = 0.12 mm⁻¹
T = 293 (2) K
0.51 × 0.49 × 0.31 mm

Data collection

Bruker SMART CCD area-detector diffractometer
Absorption correction: multi-scan (SADABS; Sheldrick, 1996 ▶) T _min = 0.802, T _max = 1.000 (expected range = 0.772–0.963)
8073 measured reflections
3220 independent reflections
2745 reflections with I > 2σ(I)
R _int = 0.087

Refinement

R[F ² > 2σ(F ²)] = 0.042
wR(F ²) = 0.092
S = 0.97
3220 reflections
405 parameters
12 restraints
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.20 e Å⁻³
Δρ_min = −0.21 e Å⁻³

Data collection: SMART (Bruker, 2003 ▶); cell refinement: SMART; data reduction: SAINT (Sheldrick, 2008 ▶) and SHELXTL (Sheldrick, 2008 ▶); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL.

Supplementary Material

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536808006387/av2007sup1.cif

e-64-0o714-sup1.cif^{(27.5KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536808006387/av2007Isup2.hkl

e-64-0o714-Isup2.hkl^{(157.9KB, hkl)}

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Table 1. Hydrogen-bond geometry (Å, °).

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O2—H2A⋯O15ⁱ	0.87 (4)	1.83 (4)	2.697 (3)	171 (4)
O3—H3A⋯O4ⁱⁱ	0.87 (4)	1.78 (4)	2.652 (3)	179 (3)
O4—H4A⋯O10	0.829 (19)	1.98 (2)	2.799 (3)	168 (3)
O9—H9A⋯O11ⁱⁱⁱ	0.80 (4)	1.96 (4)	2.724 (3)	161 (3)
O10—H10⋯O3ⁱⁱ	0.828 (19)	2.18 (2)	2.993 (3)	166 (3)
O11—H11A⋯O3ⁱⁱ	0.816 (19)	1.92 (2)	2.668 (3)	153 (3)
O15—H15A⋯O9	0.89 (2)	2.04 (2)	2.909 (3)	165 (5)
O15—H15B⋯O2ⁱⁱ	0.88 (2)	1.96 (2)	2.820 (3)	167 (5)

Open in a new tab

Symmetry codes: (i) Inline graphic ; (ii) ; (iii) .

Acknowledgments

The X-ray data were collected at Shanghai Institute of Organic Chemistry with the kind help of Dr Jie Sun. Financial support from the Shanghai Rising Star Program (grant No. 06QA14018), Shanghai Pujiang Program (grant No. 05PJ14315), Natural Science Foundation of Shanghai (grant No. 04ZR14042) and DAXIA Science Research Foundation of East China Normal University (grant No. KY2005-017) is gratefully acknowledged

supplementary crystallographic information

Comment

Para-nitrophenyl-α-L-rhamnoside is an important substrate in the studies on α-L-rhamnosidase, for its chromogenic property of the released para-nitrophenol (Garegg et al., 1978). It also serves as synthetic intermediate for glycosidic compounds (Martearena et al., 2003).

In order to develop a greener synthetic method, a series of approaches have been carried out in this lab. A fairly convenient route was found finally, in which the title compound was synthesized in only two steps. First, L-rhamnose (1) was acetylated and chlorinated to yield 2,3,4-tri-O-acetyl-α-L-rhamnopyranosyl chloride (2) in the presence of acetyl chloride; then it was converted to the target molecule (3) in the condition of phase transfer catalyst (Scheme 1). The synthetic route was more concise compared with published methods (Garegg & Norberg, 1983). Additionally, the bioactivity of the synthetic compound was confirmed by enzymatic assay (Nishio et al., 2004)

Suitable crystals of target product were obtained by slow crystallization from 95% ethanol. The crystal structure was determined in order to ascertain its stereochemistry and solid-state conformation. These data are consistent with the proton and carbon NMR studies. Due to the absence of heavy atoms, refinement of the Flack parameter was not possible, and the absolute configurations could not be determined directly. Instead, they were assigned based on the knowledge of stereochemistry of the synthetic precursors and the mechanisms of synthesis. The crystal of rhamnoside has two molecules and one water molecule in the independent part of the unit cell. The configuration, conformation and atom numbering are shown in Fig. 1.

Similar to the known structures of the nitrophenyl glycopyranosides, the analyzed rhamnopyranoside (3) crystallizes in the P 2₁ space group. Besides, one of the nitro groups is slightly rotated with respect to the phenyl fragments. The angles between the best planes of the phenyl ring and the nitro groups are 13.3° and 0.5°, respectively. This finding partly supports the earlier opinion that the nitro group does not conjugate effectively with the benzene ring (Temeriusz et al., 2005). The sugar moieties adopt ⁴C₁ conformations. Fig. 2 shows the intermolecular interactions in the crystal lattice. The crystal structure of (3) consists of molecular sheets lying perpendicular to the b axis (Fig. 2), in which the molecules are linked by short hydrogen bonds (Table 1).

For related literature, see [type here to add references to related literature].

Experimental

Para-nitrophenyl-α-L-rhamnoside (3) was obtained upon one-pot reaction combined with glycosylation and deacetylation, using 10%NaOH aqueous and cetyl alkyl trimethyl ammonium bromide from 2,3,4-tri-O-acetyl-α-L-rhamnosyl chloride and para-nitrophenol. A yield of 37% of the title compound was obtained after purification by flash column chromatography on silica gel with petroleum ether–ethyl acetate (1:3) as solvent. The compound was then recrystallized via solvent evaporation (ethanol) at room temperature, appearing as colorless blocks. Analysis: Mp: 179–180°C, [α]^D₂₀ -158.7° (c 1.0, EtOH) Rf 0.49 (dichloromethane/ methanol, 8:1, silica-gel plate 60 F₂₅₄); 1H-NMR (CD₃OD, 500 MHz, p.p.m.): δ 8.22(2H, aromatic H), 7.25(2H, aromatic H), 5.60(d, 1H, J1, 2=2 Hz, H-1), 4.03(m, 1H, H-2), 3.84(dd, 1H, H-3), 3.56–3.36(m, 2H, H-4, H-5), 1.22(d, 3H, CH3); 13 C-NMR (125 MHz, CD3OD): δ 150.83, 141.85, 124.75, 115.62(aromatic C), 98.01(C-1), 71.62, 70.15, 69.75, 69.34(C-2, C-3, C-4, C-5), 16.07(C-6).