Figure 7. Stabilization of β-mannosylation product through a CH-π interaction.

A. Structure of the bis-thiourea catalyst developed by Jacobsen Group for specific β-mannosylations and β-rhamnosylations, with the portion of the molecule that could interact with the α-face of mannose circled in red. B. Potential stacking interaction of aryl group on catalyst with the strongly CH-π donating α-face of the β-mannoside product. This interaction does not occur in the α-linked starting material. Adapted from Li et al. 2020.¹⁰⁵