Phenyl 4,6-di-O-acetyl-2,3-dide­oxy-1-thio-α-d-erythro-hex-2-enopyran­oside

Henok H Kinfe; Fanuel M Mebrahtu; Alfred Muller

doi:10.1107/S1600536811040165

. 2011 Oct 5;67(Pt 11):o2840–o2841. doi: 10.1107/S1600536811040165

Phenyl 4,6-di-O-acetyl-2,3-dideoxy-1-thio-α-d-erythro-hex-2-enopyranoside

Henok H Kinfe ^a,^*, Fanuel M Mebrahtu ^a, Alfred Muller ^a,^*

PMCID: PMC3247579 PMID: 22219884

Abstract

The pyranosyl ring in the title compound, C₁₆H₁₈O₅S, adopts an envelope conformation, with the acetyl groups in equatorial positions. In the crystal, weak C—H⋯O interactions link the molecules into chains.

Related literature

For details of the Ferrier arrangement, see: Ferrier & Prasad (1969 ▶). For the synthesis of pseudoglycals utilizing the Ferrier arrangement, see: López et al. (1995 ▶); Yadav et al. (2001 ▶). For applications of pseudoglycals, see: Domon et al. (2005 ▶); Danishefsky & Bilodeau (1996 ▶); Griffith & Danishefsky (1991 ▶); Halcomb et al. (1995 ▶); Bracherro et al. (1998 ▶); Dorgan & Jackson (1996 ▶); Chambers et al. (2005 ▶); Minuth & Boysen (2009 ▶). For background to the synthetic methodology of glycosides, see: Kinfe et al. (2011 ▶). For the preparation of the acid catalyst NaHSO₄-SiO₂, see: Breton (1997 ▶). For ring puckering analysis see, Cremer & Pople (1975 ▶). For a description of the Csambridge Structural Database, see: Allen (2002 ▶).

Experimental

Crystal data

C₁₆H₁₈O₅S
M _r = 322.36
Monoclinic,
a = 5.2330 (4) Å
b = 13.470 (1) Å
c = 11.1760 (9) Å
β = 97.291 (2)°
V = 781.41 (10) Å³
Z = 2
Mo Kα radiation
μ = 0.23 mm⁻¹
T = 100 K
0.42 × 0.37 × 0.27 mm

Data collection

Bruker APEXII DUO 4K KappaCCD diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2008 ▶) T _min = 0.910, T _max = 0.941
10609 measured reflections
3839 independent reflections
3771 reflections with I > 2σ(I)
R _int = 0.020

Refinement

R[F ² > 2σ(F ²)] = 0.025
wR(F ²) = 0.066
S = 1.06
3839 reflections
201 parameters
1 restraint
H-atom parameters constrained
Δρ_max = 0.31 e Å⁻³
Δρ_min = −0.20 e Å⁻³
Absolute structure: Flack (1983 ▶), 1824 Friedel pairs
Flack parameter: 0.04 (4)

Data collection: APEX2 (Bruker, 2011 ▶); cell refinement: SAINT (Bruker, 2008 ▶); data reduction: SAINT and XPREP (Bruker, 2008 ▶); program(s) used to solve structure: SIR97 (Altomare et al., 1999 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: DIAMOND (Brandenburg & Putz, 2005 ▶); software used to prepare material for publication: WinGX (Farrugia, 1999 ▶).

Supplementary Material

Crystal structure: contains datablock(s) global, I. DOI: 10.1107/S1600536811040165/fj2451sup1.cif

e-67-o2840-sup1.cif^{(24.9KB, cif)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536811040165/fj2451Isup2.hkl

e-67-o2840-Isup2.hkl^{(184.4KB, 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
C13—H13B⋯O5ⁱ	0.98	2.44	3.3506 (15)	154

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Symmetry code: (i) Inline graphic .

Acknowledgments

Research funds of the University of Johannesburg and the Research Center for Synthesis and Catalysis are gratefully acknowledged. Mr C. Ncube is thanked for the data collection.

supplementary crystallographic information

Comment

Glycals, 1,2-unsaturated pyranoses, undergo acid catalyzed allylic rearrangement in the presence of alcohols to provide 2,3-unsaturated glycosides (pseudoglycals) (see Ferrier & Prasad, 1969). This reaction is referred as the Ferrier rearrangement reaction. Since the reaction proceeds via an oxycarbonium intermediate, thiols, halides and other nucleophiles can be employed besides alcohols to produce corresponding glycosides (see López et al., 1995; Yadav et al., 2001). The pseudoglycal products from the Ferrier rearrangement reaction have been used as chiral building blocks in the synthesis of antibiotics (see Domon et al., 2005), oligosaccharides (see Danishefsky & Bilodeau, 1996; Griffith & Danishefsky, 1991; Halcomb et al., 1995), nucleosides (see Bracherro et al., 1998), glycopeptides (see Dorgan & Jackson, 1996; Chambers et al., 2005) and also as chiral ligands in asymmetric synthesis (see Minuth & Boysen, 2009). Among other thioglycosides, phenyl 2,3-unsaturated thioglycosides have been extensively employed in organic synthesis such as in the elegant total synthesis of allosamidin (chitinase inhibitor), esperamicin and Calicheamicin (see Danishefsky & Bilodeau, 1996; Griffith & Danishefsky, 1991; Halcomb et al., 1995). Due to the importance of this type of thioglycosides, herein we report the structural analysis of phenyl 2,3-unsaturated thioglycoside I.

The title compound (see Fig. 1, scheme 1) crystallizes in the P2₁ (Z=2) space group resulting in molecules lying on general positions in the unit cell. All bond lengths are within their normal ranges (Allen, 2002) with the acetyl groups all in equatorial positions. The pyran ring is in an envelope conformation with ring puckering parameters of q₂ = 0.4212 (12) Å, q₃ = 0.2974 (12) Å, Q = 0.5156 (11) Å and φ₂ = 321.05 (17)° (see Cremer & Pople, 1975). Weak C—H···O/S interactions (see Table 1) stabilize the crystal structure.

Experimental

To a solution of a tri-O-acetyl-D-glucal (100 mg, 0.36 mmol) in CH₃CN (1 ml) NaHSO₄-SiO₂ (2.5 mg, 3.0 mmol NaHSO₄/g) was added (see Breton, 1997). The resulting mixture was stirred at 80 °C for 5 min. After adding silica gel to the reaction mixture at room temperature, the solvent was evaporated in vacuo without heating until a free-flowing solid was obtained. The resulting solid was column chromatographed using 1:9 ethyl acetate:hexane eluent to afford α:β (4:1) mixture of 2,3-unsaturated glycosides in 96% yield as a white solid (see Kinfe et al., 2011). Recrystalization from a mixture of DCM and hexane afforded the title thioglycoside I in 60% yield as white crystals. Analytical data: ¹H NMR (CDCl₃, 300 MHz): δ 7.51 (d, J = 7.2 Hz, 2H), 7.29–7.17 (m, 3H), 6.03 (d, J = 10.2 Hz, 1H), 5.83 (d, J = 10.8 Hz, 1H), 5.73 (s, 1H), 5.35 (d, J = 9.6 Hz, 1H), 4.60–4.13 (m, 3H), 2.07 (s, 3H), 2.03 (s, 3H); ¹³C NMR (CDCl₃, 75 MHz): δ 170.7, 170.2, 134.7, 131.7, 128.9, 128.5, 127.6, 83.6, 67.2, 65.0, 63.0, 20.9, 20.7.