First total synthesis of α-(2→3)/α-(2→6)-disialyl lactotetraosyl ceramide and disialyl Lewis A ganglioside as cancer-associated carbohydrate antigens Original Research Article

The first total synthesis of α-(2→3)/α-(2→6)-disialyl lactotetraosyl (DSLc4) ceramide and α-(2→3)/α-(2→6)-disialyl Lewis A (DSLea) ganglioside as cancer-associated antigens is described. The suitably protected lactotriose (Lc3) derivatives were successively glycosylated with sialic acid, sialyl-α-(2→3)-d-galactose and/or l-fucose donors in a regio- and stereo-selective manner, to give the protected type I hexa- and hepta-saccharides, respectively, which were then converted to the target gangliosides by the introduction of ceramide and subsequent complete deprotection.