Pivalates in the selective protection and activation of maltose for the synthesis of sulfated 3-deoxy-maltosyl-(1 → 4)-α,α-trehalose

Pivaloylation of maltose gave, in satisfactory yield, 1,2,6,2′,3′,4′,6′-hepta-O-pivaloyl-β-maltose which was converted to the 3-deoxygenated analogue in a Barton-McCombie reaction. This compound was used directly in a trimethylsilyl triflate-mediated glycosylation reaction with 2,3,6-tri-O-benzyl-α-d-glucopyranosyl 2,3-di-O-benzyl-4,6-O-benzylidene-α-d-glucopyranoside to give the corresponding maltosyl-(1 → 4)-α,α-trehalose derivative. After deprotection, the monodeoxygenated tetrasaccharide was sulfated; in the reaction product, one compound fully sulfated at the outer pyranose rings predominated. © 1997 Elsevier Science Ltd.