α‐<scp>D</scp>‐Glycosyl‐Substituted α,α‐<scp>D</scp>‐Trehaloses with (1 → 4)‐Linkage: Syntheses and NMR Investigations

Abstract

Abstract 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) 2 O) as a new reactive promoter yielding 92% of trisaccharide 14 , deblocking gave the target saccharide α‐ D ‐glucopyranosyI‐( 1 → 4 )‐α,α‐ D ‐trehalose. 1 H‐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.