Chemical synthesis of an artificial antigen containing the trisaccharide hapten of Mycobacterium leprae

The crystal and the molecular structure of 4,1′,6′-trichloro-4,1′,6′-trideoxy-galacto-sucrose (TGS) was determined by X-ray analysis at 294 K. Crystals of TGS are orthorhombic, space group P2₁2₁2₁, with a = 7.318(3), b = 12.027(4), c = 18.136(5) Å, V = 1596(1) ų, Z = 4; D_x = 1.655 g.cm^-3, λ(MoK) = 0.71073 Å, μ(MoK) = 5.44 cm^-1, F(000) = 816. The X-ray intensities of 2649 reflections with I 2.5σ(I) were measured with Zr-filtered MoK-radiation. The structure was solved by the Patterson procedure and refined by full-matrix least-squares to a final R-value of 0.0298. Large conformational differences between TGS and sucrose were observed, particularly in the conformation of the glycosidic linkage. These differences originate from chlorine substitution, which affects intramolecular hydrogen bonding and sweet-taste glucophores.