On the Reactivity of Gulose and Guluronic Acid Building Blocks in the Context of Alginate Assembly
A novel set of L-gulose and L-guluronic acid building blocks, comprising both monosaccharide and disaccharide synthons, was assembled to investigate how structural changes in these synthons influence the outcome of glycosylation reactions in which they are involved. Our studies corroborate previous reports that identified the gulosyl C4-OH group as a relatively poor nucleophile. We did not find a major influence of the neighboring C5 functionality on the reactivity of the alcohols, and the gulose acceptors did not provide more productive glycosylation reactions than their guluronic acid counterparts. The conformational behavior of the synthons was found to be of prime importance to the outcome of the reactions.