Selective derivatization of d-galactose towards a practical synthesis of C-6 l-fucose analogues

Starting from d-galactose, a convenient protocol is described for the synthesis of l-fucose C-6 analogue, 2,3,4,5-tetra-O-acetyl-5-(1,3-dithiolan-2-yl)-l-galactopyranose, in an overall yield of 40% after 6 steps, making use of stable intermediates. A chemoselective protection/deprotection strategy was studied using TBDMS and TBDPS silyl ethers for protection of d-galactose primary hydroxyl group.