RCM approaches toward the diastereoselective synthesis of vicinal trans-diaminocyclitols from L-serine

Starting from L-serine, the asymmetric synthesis of four diaminocyclitol derivatives as sugar-based glycosidase inhibitors has been achieved using ring-closing metathesis (RCM) as a key step. Introduction of vicinal trans-diamino functionality onto the acyclic precursors was accomplished by highly diastereoselective addition of Grignard reagent to imine, and the elaboration of polyhydroxylic groups was effected via diastereoselective olefin epoxidation or dihydroxylation. The absolute configurations of final products were confirmed by 2D NMR studies.