Synthesis of ß-D-Galf-(1-3)-D-GlcNAc by the Trichloroacetamidate Method and of ß-D-Galf-(1-6)-D-GlcNAc by SnCl4-Promoted Glycosylation

CAROLA, GALLO-RODRÍGUEZ; LUCÍA, GANDOLFI-DONADÍO; ROSA, M. DE LEDERKREMER

ORGANIC LETTERS

American Chenical Society

Lugar: Washington, DC; Año: 1999 vol. 1 p. 245 - 247

1523-7060

In continuation of our studies on the characterization of the glycoproteins of T. cruzi new galactofuranosyl disaccharides were synthesized. b-D-Gal f-(1-3)-D-GlcNAc (1) was prepared employing the trichloroacetamidate procedure for the glycosylation step. The mild conditions of this reaction are appropriate for condensation of 2,3,5,6- tetra- O-benzoyl-b-D-galactofuranosyl trichloroacetamidate (6) with acid labile benzyl 2-acetamido-4,6- O-benzylidene- 2-deoxy-a-D-glucopyranoside (3). On the other hand, tin(IV) chloride-promoted condensation of benzyl 2-acetamido- 3- O-benzoyl-2-deoxy-a-D-glucopyranoside (11) with penta-O-benzoyl-a,b-D-galactofuranose (4) gave the derivative ofb-D-Gal f-(1-3)-D-GlcNAc (1) was prepared employing the trichloroacetamidate procedure for the glycosylation step. The mild conditions of this reaction are appropriate for condensation of 2,3,5,6- tetra- O-benzoyl-b-D-galactofuranosyl trichloroacetamidate (6) with acid labile benzyl 2-acetamido-4,6- O-benzylidene- 2-deoxy-a-D-glucopyranoside (3). On the other hand, tin(IV) chloride-promoted condensation of benzyl 2-acetamido- 3- O-benzoyl-2-deoxy-a-D-glucopyranoside (11) with penta-O-benzoyl-a,b-D-galactofuranose (4) gave the derivative ofb-D-galactofuranosyl trichloroacetamidate (6) with acid labile benzyl 2-acetamido-4,6- O-benzylidene- 2-deoxy-a-D-glucopyranoside (3). On the other hand, tin(IV) chloride-promoted condensation of benzyl 2-acetamido- 3- O-benzoyl-2-deoxy-a-D-glucopyranoside (11) with penta-O-benzoyl-a,b-D-galactofuranose (4) gave the derivative ofa-D-glucopyranoside (3). On the other hand, tin(IV) chloride-promoted condensation of benzyl 2-acetamido- 3- O-benzoyl-2-deoxy-a-D-glucopyranoside (11) with penta-O-benzoyl-a,b-D-galactofuranose (4) gave the derivative ofa-D-glucopyranoside (11) with penta-O-benzoyl-a,b-D-galactofuranose (4) gave the derivative of b-D-Gal f-(1-6)-D-GlcNAc (2) in 78 % yield.-D-Gal f-(1-6)-D-GlcNAc (2) in 78 % yield.