Stereoselective synthesis of a novel branched-chain (1S,2R,6R,7S)-7a-(hydroxymethyl)-1,2,6,7-tetrahydroxypyrrolizidine

Abstract An efficient and highly stereoselective approach towards a new type of branched-chain pentahydroxylated pyrrolizidine 7 from a d -glucose isothiocyanate scaffold has been developed. The key features of this strategy are the construction of a diene-substrate foldamer possessing an amino functional group followed by subsequent ring-closing metathesis, an intramolecular cyclisation readily induced by regioselective tosylation to establish the pyrrolizidine unit and a highly diastereoselective, substrate-controlled dihydroxylation.