10.1021/ol501631r
The research focuses on the first synthesis of (?)-pericosine E, a marine natural product metabolite derived from the sea hare Aplysia kurodai. The study developed efficient and regioselective synthetic procedures for key intermediates, specifically anti- and syn-epoxides 9 and 10. The synthesis involved the use of anti-epoxidation of diene 12 with TFDO and bromohydrination of 12 with NBS in a CH3CN/H2O solvent system. The research compared the specific optical rotations of synthetic and natural 6 to confirm the absolute configuration of the naturally occurring enantiomer. The experiments utilized various reactants, including (?)-shikimic acid, alcohol 13, triflate 14, CsOAc, DMF, NBS, LHMDS, THF, HCl, and BF3?Et2O, among others. Analyses were conducted using techniques like 1H?1H COSY, NOESY, HSQC, and HMBC to establish the regio- and stereochemistry of the products and byproducts. The study concluded with the successful synthesis of (?)-pericosine E and the determination of its absolute configuration, which was found to match that of the naturally preferred enantiomer.
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.
10.1021/ol0340383
The research aims to develop non-carbohydrate-based glycomimetics targeting the C-type lectin family, which are involved in immune system regulation. The researchers utilized shikimic acid as a key building block due to its three hydroxyl groups that can be arranged in a configuration mimicking the carbohydrate ligands of C-type lectins. They employed two solid-phase, parallel synthesis strategies on a resin support to create two libraries of compounds. The first library was synthesized using monothiols as building blocks, while the second library incorporated dithiols and alkyl bromides for additional diversity. The compounds' ability to inhibit the binding of the C-type lectin MBP-A was assessed using a high-throughput bead-elution binding assay. The study identified 10 compounds with inhibitory activities comparable to that of R-methyl mannopyranoside, indicating that shikimic acid is a valuable scaffold for creating potent glycomimetics. The findings suggest that this synthetic strategy could be a general method for producing selective inhibitors of C-type lectins, potentially leading to new therapeutic agents.