Syntheses and ¹H-NMR Studies of Methyl 4, 6-Di-O-glucopyranosyl-β-D-glucopyranosides Chirally Deuterated at the (1→6)-Linkage Moiety

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Four stereoisomers of methyl 4, 6-di-O-D-glucopyranosyl-β-D-glucopyranosides, in which the H-6proS proton at the (1→6)-linkage moiety was selectively replaced by a deuterium (²H), were synthesized through the photobromination of 1, 6-anhydro-per-O-acetyl-β-D-maltopyranose and β-D-glucose, with subsequent deuteride reduction of the brominated products (C-6exo bromides) by tri-n-butyltin deuteride. The chirally deuterated sugars enabled us to differentiate the H-6proR and H-6proS signals at the (1→6)-linkage moiety and, thereby, to clarify the conformational distributions about the C5-C6 bonds.