α-D-Glycosyl-Substituted α,α-D-Trehaloses with (1 → 4)-Linkage: Syntheses and NMR Investigations

Two symmetrical trehalose glycosyl ‘acceptors’ 4 and 6 were prepared and three of the unsymmetrical type, 8, 10, and 11. Glucosylation of symmetrical ‘acceptor’ 4 gave a higher yield of trisaccharide (44%) than protect ve‐group manipulation, namely via selective debenzylidenation 2 → 9 or monoacetylation 2 → 5 which proceeded in moderate yields (33–34%). A comparison of catalysts in the cis‐glucosylation of trehalose ‘acceptor’ 10 with tetra‐O‐benzyl‐β‐D‐glucopyranosyl fluoride 13 profiled triflic anhydride ((Tf)2O) as a new reactive promoter yielding 92% of trisaccharide 14, deblocking gave the target saccharide α‐D‐glucopyranosyI‐(1 → 4)‐α,α‐D‐trehalose. 1H‐NMR spectra of most compounds were analyzed extensively. The use of the ID TOCSY technique is advocated for its time efficiency, if needed supplemented by ROESY experiments.