Chemical transformations of αα-trehalose

Abstract

αα-Trehalose reacts with acetaldehyde to form crystalline di- and hexa-O-ethylidene compounds analogous to the known compounds of methyl D-glucoside. Di-O-ethylidene-αα-trehalose can be mesylated and tosylated to form crystalline products. The time necessary for complete tosylation indicates that secondary hydroxyl groups are reacting. By analogy with D-glucose and methyl D-glucoside, the compounds are probably 4,6 : 4′,6′-di-O-ethyl-idene-αα-trehalose and 4,6 : 4′,6′-di-O-ethylidene-2,3 : 2′,3′-di-O-(oxydiethylidene)-αα-trehalose. The formation of these compounds lends support to the idea that the known glucopyranose rings in αα-trehalose are in the C1 conformation. The synthesis of 6,6-dideoxy-αα-trehalose is described.