3,4-Dicyanophenyl 2,3,4,6-tetra-O-acetyl-α-d-glucopyranoside

The title compound, C22H22N2O10, was prepared by the glycosidation method through nitrite displacement on substituted nitrophthalonitrile. The molecule contains a benzene ring, two nitrile groups and an acetyl-protected d-glucose fragment which adopts a chair conformation. The absolute configuration was determined by the use of d-glucose as starting material. All substituents of the protected sugar are in equatorial positions, with the exclusive presence of the α-anomer. The crystal packing is stabilized by C—H⋯O and C—H⋯N hydrogen-bonding interactions.


Related literature
Data collection: XSCANS (Bruker, 1996); cell refinement: XSCANS; data reduction: XSCANS; program(s) used to solve structure: SHELXTL (Bruker, 1997); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL. supporting information Acta Cryst. (2008). E64, o63 [https://doi.org/10.1107/S1600536807049860] 3,4-Dicyanophenyl 2,3,4,6-tetra-O-acetyl-α-D-glucopyranoside Yuejing Bin, Fuqun Zhao, Fushi Zhang and Ru-Ji Wang S1. Comment Phthalocyanine has been used in applications based upon their close structural relationship of the phthalocyanines with porphyrin complexes. However, a serious limitation of phthalocyanine is their insolubility. Phthalocyanine compounds are made soluble in a variety of solvents by appropriate peripheral substitution. The synthesis routes of amphiprotic glucose-appended phthalocyanines include the preparation of dicyanophenyl glucopyranoside as precursor and further macrocyclization forming phthalocyanine-glucoconjugates. These glucose-appended phthalocyanines are highly soluble and self-assemble in water (Ribeiro et al., 2006). Aggregation of these phthalocyanine compounds in solution and in the solid state significantly affects the optical properties of such solutions and films. The crystal structure of phthalocyanine is difficult to attain. The structure of the precursors could provide some clues to elucidate the self-assembly of phthalocyanine-glucocongates. The precursor of the phthalocyanine-glucoconjugates is the title compound, 3,4-dicyanophenyl 2,3,4,6-tetra-O-acetyl-α-D-glucopyranoside, which was prepared by the glycosidation method through nitrite displacement on substituted nitrophthalonitrile. The main products were exclusively the thermodynamically favored αanomers obtained by reversible SNAr reactions in polar aprotic solvents like Me 2 SO or DMF in the presence of a base (Berven et al., 1990). We report here the crystal structure of the title compound.
In the title compound ( Fig. 1) the 2,3,4,6-tetra-O-acetyl-D-glucopyranoside ring mean plane is oriented exactly perpendicular to that of the phthalocyanine ring. The four acetyl groups with atoms are in equatorial positions (Burkhardt et al., 2007). The crystal structure reveals a 4 C 1 chair conformation for the sugar ring, with the 3,4-dicyanophenyl substituent at C9 in the vertical position, corresponding to the exclusive presence of the α-anomer of the saccharide, in agreement with the 1 H NMR results (Alvarez-Mico et al., 2006, 2007. The C1≡N1 (1.132 (8) Å) and C2≡N2 (1.130 (8) Å) bond distances are consistent with a triple bond character, and are in good agreement with the literature values (Dinçer et al., 2004;Ocak et al., 2004;Huang et al., 2005).

S2. Experimental
A suspension of anhydrous D-glucose (25 g, 0.15 mol) and anhydrous sodium acetate (12.5 g, 0.15 mol) in 100 mL (1.1 mol) of acetic anhydride was slowly heated to reflux temperature in a round-bottomed flask. Then the heater was removed and the reaction left to reflux. Once the colour of the solution changed from colourless to yellow, the solution was poured onto l liter of crushed ice and stirred for 2 h. The solid product was filtered off, washed with water and recrystallized from ethanol to yield colourless crystals of 1,2,3,4,6-penta-O-acetyl-D-glucopyran (27 g; yield 50%; m. p. 135° C). To a solution of ethylenediamine (1.2 g, 20 mmol) in DMF (10 ml), glacial acetic acid (1.2 g, 20 mmol) was added dropwise, then 1,2,3,4,6-penta-O-acetyl-D-glucopyran (7.8 g, 20 mmol) was added and the mixture stirred at RT for 5 h. Water (100 ml) was added and the mixture extracted with acetic ester. The organic phase was subsequently supporting information washed with 2 N HCl, saturated NaHCO 3 solution and concentrated in vacuo. The compound obtained (5.0 g, 14.4 mmol) and 4-nitrophthalodinitrile (1.8 g, 10.4 mmol) were dissolved in DMF (15 ml), the new roasted anhydrous potassium carbonate (4 g) was added to the solution as three batches in 1 h, and stirred at R. T. for 48 h. The mixture was poured into ice water, and the precipitated product was filtered off, washed with water and recrystallized from toluene to give the title compound (2.4 g; yield 50%; m. p. 159-160° C; m/z 497.23 [M+Na] + ).

S3. Refinement
All hydrogen atoms were generated geometrically with C-H = 0.93-0.97 Å and included in the refinement with U iso (H) = 1.2U eq (aromatic and methylene C) or 1.5U eq (C) (methyl C). In the absence of significant anomalous dispersion effects Friedel pairs were merged prior to the final refinement. The absolute configuration was determined by the use of Dglucose as starting material.

Figure 1
The molecular structure of the title compound with 35% probability ellipsoids and the atom numbering scheme.  Packing diagram of the title compound viewed along the α axis. H atoms are omitted for clarity.

Special details
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 F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > σ(F 2 ) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.