Synthesis and trehalase-inhibitory activity of an imino-linked dicarba-α,α-trehalose and analogues thereof

Dicarba-α,α-trehalose 2a, bis-(5a-carba-α-D-glucopyranosyl)amine, was prepared by the coupling of di-O-isopropylidene-α-validamine 5 and protected carba-sugar epoxide 7, followed by removal of the 2′-hydroxy group and conventional deprotection. Likewise, imino-linked dicarba-α,α-trehalose analogues 3a and 4a, composed of valienamine and valiolamine moieties, were synthesized by reaction of protected valienamine 6 and valiolamine 24 with the epoxides 7 and 29, respectively. Compounds 2a, 3a, and 4a were shown to possess strong inhibitory activity against trehalase, being compatible with validoxylamine A 1.