Chemical esterification of α,α-trehalose with two different dipeptide acyl donors, Boc-Phe-Met-OH and Boc-Gly-Gly-OH, gave a set of products differing in the number and site of substitution. With both dipeptides 6,6\u27-diester was isolated as the major product. In the Boc-Phe-Met-OH line, the dipeptide units in all higher substituted esters were asymmetrically distributed between the two trehalose rings. In contrast, the first higher substituted Boc-Gly-Gly-OH derived ester found was the symmetric 2,2\u27,6,6\u27-tetraester. These four sites remained occupied in all other isolated products, two asymmetric pentaesters and one symmetric hexaester. The data presented here show that in addition to sugar hydroxyl group reactivity, the structural properties of the acylating reagent, in particular its sterical demands, are of the utmost importance for the distribution and arrangement of acyl moieties around the non-reducing disaccharide core molecule
