Reaction of de-N-acetyl gangliosides GM(1) (Ib) and GM(3) (2b) with me
thyl dithioacetate (3) afforded N-thioacetyl GM(1) (Ic) and N-thioacet
yl GM(3) (2c) with the oxygen of the acetamido group of N-acetylneuram
inic acid residue replaced by sulfur.