Study on systematizing the synthesis of the a-series ganglioside glycans GT1a, GD1a, and GM1 using the newly developed N-Troc-protected GM3 and GalN intermediates

A first systematic synthesis of the glycan parts of the a-series gangliosides (GT1a, GD1a, and GM1) utilizing the newly developed N-Troc-protected GM3 and galactosaminyl building blocks is described. The key processes, including the assembly of the GM2 sequence and its conversion into the 3-hydroxy acceptor, were facilitated mainly by the high degree of participation and chemoselective cleavability of the Troc group in the galactosaminyl unit. Furthermore, the novel GM2 acceptor served as a good coupling partner during glycosylation with galactosyl, sialyl galactosyl, and disialyl galactosyl donors, successfully producing the GM1, GD1a, and GT1a glycans. (C) 2009 Elsevier Ltd. All rights reserved.