β-Glucosidase inhibitors incorporating pyridinium as a glucosyl mimic

The synthesis of several 2-pyridylthio-based pseudo-disaccharides (5 – 9) is described. One of them, 5a, shows inhibition of Agrobacterium β-glucosidase (Ki = 800 μM), possibly because in protonated form it mimics the protonated substrate (or transition state, compare 1) leading to the glucopyranosyl cation.