Sweet taste induction by alkyl 2,3-di-O-(l-aminoacyloxy)-α-d-glucopyranosides requires a combination of hydrophobic α-alkoxy and hydrophilic vicinal, diequatorially oriented, l-aminoacyloxy units. Pyranoside chair conformations afford the preferred stereochemical arrangements of these residues for optimum interaction with the receptor. For the design of new sweeteners based on sweetness inhibitors, the introduction of a di-O-aminoacyloxy unit as the hydrogen-bonding component was applied to effect their intertransformation. Thus, the known sweetness inhibitor, methyl 4,6-dichloro-4,6-dideoxy-α-d-galactopyranoside, was successfully transformed into sweet-tasting 2,3-di-O-(l-aminoacyl) derivatives. The inhibition of the 4,6-dichloro derivative is therefore competitive. Amongst the related amino-chloro-deoxysugars, methyl 6-chloro-6-deoxy-2,3-di-O-(l-alanyl)-α-d-gluco-pyrano side was found to be a full agonist. Our studies were then extended to disaccharide derivatives based on trehalose. This approach led to new highly intense sweeteners, as dimeric forms of the full agonist 2,3,2',3'-tetra-O-(l-alanyl)-6,6'-dichloro-6,6' -dideoxytrehalose. The derivatives with effective hydrophobic groups on the C-6 and C-6' positions, were found to be up to 8001000 times sweeter than sucrose.
Design and synthesis of new sweeteners
