Abstract The useful constructions of β-d-mannosidic, 2-acetamido-2-deoxy-β-d-mannosidic, and 2-deoxy-β-d-arabino-hexopyranosidic units from the same intermediate, 2,4-bis(O-trifluoromethanesulfonyl) derivative of β-d-galactoside, were achieved in a stepwise inversion at C-4 and C-2 by using cesium acetate, Bu4NBH4 and Bu4NN3 in good yields. Convenient and practical protections of β-d-mannoside to the straightforward synthesis of antennary oligosaccharides also achieved by using cesium trifluoroacetate.