10.1021/ol201252x
The research focuses on the divergent synthesis of (-)-4-epi-shikimic acid, a glycomimetic building block, which is crucial for mimicking carbohydrates and their interactions with C-type lectins (CLECs), proteins involved in physiological and pathological processes. The synthesis route involves a one-pot zinc-mediated reductive ring opening of arabinofuranose, followed by a Barbier reaction and culminating in a ring-closing metathesis. The researchers used D-arabinose as the starting material, converting it to furanose 9 through acid-catalyzed ring contraction, and then to iodosugar 6 using Mitsunobu conditions. The key experiments included optimizing conditions for the Barbier reaction and ring-closing metathesis, with the latter being particularly challenging due to the reactivity of 1,1-disubstituted acrylates. The analyses used to monitor the progress and confirm the structures of the synthesized compounds included NMR and mass spectrometry. The overall yield of the synthetic route was 32%, and the utility of (-)-4-epi-shikimic acid for generating fucose-like compounds was demonstrated through conjugate addition of a thiol, resulting in a product with high diastereoselectivity.