Synthesis of the Key Disaccharide Building Blocks 3 and 8. (TCA = trichloroacetyl, AgOTf = silver trifluoromethanesulfonate = silver triflate, TMU = 1,1,3,3-tetramethylurea, PMP = p-methoxyphenyl, PMB = p-methoxybenzyl, CSA = 10-camphorsulfonic acid, MS = molecular sieves, DMF = N,N-dimethylformamide, DME = 1,2-dimethoxyethane, THF = tetrahydrofuran).