Synthesis, Conformational Studies and Mannosidase Stability of a Mimic of 1,2-Mannobioside

Dimethyl (1S,2S,4S,5S)-4-allyloxy-5-(α-mannosyloxy)cyclohexane-1,2- dicarboxylate (3) was designed as a structural mimic of α(1,2)mannobioside (1). Its synthesis and structural analysis by NMR spectroscopy and molecular modelling are described. The results show that 3, like 1, populates two low-energy conformations - stacked (S) and extended (E) - that are in fast dynamic equilibrium around the glycosidic linkage. Thus, the data confirm the expectation that the pseudo-disaccharide can be used as a structural mimic of mannobioside. The mannosidase stability of 3 was found to be significantly higher (sixfold) than that of natural mannobioside. This is a very useful feature of this mimic and is encouraging for its future development.