6-Azido-3-O-benzyl-6-de­oxy-N,N-diethyl-1,2-O-isopropyl­idene-d-glycero-α-d-gluco-heptofuran­uronamide

S F Jenkinson; N Oña; A Romero; G W J Fleet; A L Thompson; M S Pino-González

doi:10.1107/S1600536810048944

. 2010 Dec 4;67(Pt 1):o38–o39. doi: 10.1107/S1600536810048944

6-Azido-3-O-benzyl-6-deoxy-N,N-diethyl-1,2-O-isopropylidene-d-glycero-α-d-gluco-heptofuranuronamide

S F Jenkinson ^a,^*, N Oña ^b, A Romero ^b, G W J Fleet ^a, A L Thompson ^c, M S Pino-González ^b

PMCID: PMC3050294 PMID: 21522748

Abstract

Reaction of 3-O-benzyl-1,2-O-isopropylidene-α-xylo-pentodialdo-1,4-furanose with N,N-diethyl-2-(dimethylsulfuranilidene)acetamide gave stereoselectively an epoxyamide, which was regioselectively opened by NaN₃ in dimethyl formamide to give the title compound, C₂₁H₃₀N₄O₆. X-ray crystallography confirmed the relative stereochemistry of the title compound and the absolute configuration was determined by the use of d-glucose as the starting material. There are two molecules in the asymmetric unit (Z′ = 2). The crystal structure consists of two types of chains of O—H⋯O hydrogen-bonded molecules running parallel to the b axis, with each molecule acting as a donor and acceptor of one hydrogen bond.

Related literature

For the use of sulfur ylids to form epoxyamides, see: Assiego et al. (2004 ▶); Jenkinson et al. (2009 ▶; López-Herrera et al. (1996 ▶, 1997 ▶); Oña et al. (2010 ▶); Pino-González et al. (2003 ▶, 2008 ▶); Valpuesta Fernández et al. (1990 ▶).

Experimental

Crystal data

C₂₁H₃₀N₄O₆
M _r = 434.49
Monoclinic,
a = 13.0478 (4) Å
b = 10.5547 (3) Å
c = 16.5552 (6) Å
β = 97.0347 (11)°
V = 2262.75 (13) Å³
Z = 4
Mo Kα radiation
μ = 0.09 mm⁻¹
T = 150 K
0.20 × 0.20 × 0.20 mm

Data collection

Nonius KappaCCD diffractometer
Absorption correction: multi-scan (DENZO/SCALEPACK; Otwinowski & Minor, 1997 ▶) T _min = 0.92, T _max = 0.98
15625 measured reflections
5408 independent reflections
4270 reflections with I > 2σ(I)
R _int = 0.042

Refinement

R[F ² > 2σ(F ²)] = 0.053
wR(F ²) = 0.122
S = 0.96
5408 reflections
559 parameters
1 restraint
H-atom parameters constrained
Δρ_max = 0.56 e Å⁻³
Δρ_min = −0.44 e Å⁻³

Data collection: COLLECT (Nonius, 2001 ▶); cell refinement: DENZO/SCALEPACK (Otwinowski & Minor, 1997 ▶); data reduction: DENZO/SCALEPACK; program(s) used to solve structure: SIR92 (Altomare et al., 1994 ▶); program(s) used to refine structure: CRYSTALS (Betteridge et al., 2003 ▶); molecular graphics: CAMERON (Watkin et al., 1996 ▶); software used to prepare material for publication: CRYSTALS.

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536810048944/lh5169sup1.cif

e-67-00o38-sup1.cif^{(31.8KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536810048944/lh5169Isup2.hkl

e-67-00o38-Isup2.hkl^{(270KB, 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
O33—H331⋯O40ⁱ	0.84	2.39	3.046 (5)	135
O10—H101⋯O5ⁱⁱ	0.85	2.25	2.849 (5)	127

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

Acknowledgments

We thank the Dirección General de Investigación Científica y Técnica of Spain (CTQ2007–66518/BQU) and the Consejería de Educación y Ciencia, Junta de Andalucia (FQM 158), for financial support.

supplementary crystallographic information

Comment

The stereoselective formation of epoxyamides from monosacharides and sulfur ylids and the subsequent regioselective epoxide opening has been utilized in the formation of iminosugars such as the seven-membered ring azepanes (Oña et al., 2010), pyrrolidines (Pino-González et al., 2008), pipecolic acid derivatives (Pino-González et al., 2008) and other monosaccharide derivatives as C-glycosides (López-Herrera et al., 1997) and branched furanoses (Jenkinson et al., 2009). In order to obtain new products, key intermediates in iminosugar synthesis, the reaction of semiprotected dialdose 1 with N,N-diethyl-2-(dimethylsulfuranylidene)acetamide was investigated.

Reaction of aldehyde 1, obtained from D-glucose, with the sulfur ylid gave epoxyamide 2 as the only product (Fig. 1). The subsequent regioselective opening of the epoxide with sodium azide, with acetic acid as a catalyst, gave the title compound 3. The product was confirmed, by both X-ray crystallography and the use of D-glucose as the starting material, to have the D-glycero-D-gluco stereochemistry (Fig. 2) arising from initial attack of the ylid on the re face of the aldehyde. This configuration can be predicted from a Felkin-Ahn model as corroborated for a number of aldehyde sugars with either free aldehydes or in cyclohemiacetalic form (Valpuesta Fernández et al., 1990; López-Herrera et al., 1996). In the present compound 1, the influence of 3-O-benzyl group plays a crucial role to obtain complete selectivity.

There are two crystallographically distinct molecules in the asymmetric unit which are related by a pseudo 2-fold rotation axis (Fig 2). When the two molecules are mapped they show good overlap for the majority of the structure (Fig. 3) with RMS deviations of 1.0604 on the positions, 0.0140 for the bonds and 35.7787 for the torsion angles. The major difference between the two molecules is the orientation of the aromatic ring. The crystal exists as chains of hydrogen bonded molecules lying parallel to the b-axis, with each molecule acting as a donor and an acceptor of one hydrogen bond (Fig. 4). Only classical hydrogen bonding is considered. For one of the molecules in the asymmetric unit the ethylamine moiety exhibits a greater degree of thermal motion than in the other.

Experimental

The title compound was recrystallized from dichloromethane: m.p. 375–376 K; [α]_D²⁹ -2.28 (1.4, CH₂Cl₂).