2,4,6-Tri-O-benzyl-D-galactopyranose was prepared from allyl 3-O-allyl-2,4,6-tri-O-benzyl-α-D-galactopyranoside for use in the synthesis of oligosaccharides containing a galactose residue substituted on the 3-position. The use of the but-2-enyl (crotyl) ether system for the protection of hydroxy-groups was investigated. The but-2-enyl ethers were stable to mild acid hydrolysis and to the basic conditions required for benzylation, and were readily cleaved by the action of potassium t-butoxide in dimethyl sulphoxide. Prop-1-enyl 2,4,6-tri-O-benzyl-α-D-galactopyranoside was prepared from allyl 2,4,6-tri-O-benzyl-3-O-but-2-enyl-α-D-galactopyranoside and prop-1-enyl 2-benzamido-4,6-di-O-benzyl-2-deoxy-β-D-glucopyranoside was prepared from allyl 2-benzamido-4,6-di-O-benzyl-3-O-but-2-enyl-2-deoxy-β-D-glucopyranoside. 2-Benzamido-3,4,6-tri-O-benzyl-2-deoxy-D-gluco- and D-galacto-pyranoses were prepared from the corresponding β-allyl glycosides.