Radical Cyclization in Heterocycle Synthesis. 7. Synthesis of Chiral 2-Substituted 5-Amino-4-piperidinols via Radical Cyclization

Oxime ether connected by a tether to fomyl group, which is available from natural amino acid, efficiently cyclizes viastannyl radical addition-cyclization or Sm12-induced radical reaction to provide a new entry to asymmetric synthesis of 2-substituted 5-amino-4-piperidinols.The preparation of cyclic compounds having an amino group and a hydroxyl group at the neighboring position on the ring has attracted considerable interest in recent years due to their variety of biological activities.Typical examples are h a l a n ~l , ~ dysiherbaine,3 pan~ratistatin,~ and pseudodistomins.5 Pseudodistomins A-C5b were isolated from the Okinawan tunicate Pseudodistoma kanoko and shown to have in virro antitumor activity against L1210 and L5178Y leukemia cells and inhibit calmodulin-activated brain phosphodiesterase.Pseudodistomins D-F5c were isolated from the Micronesian ascidian Pseudodistoma megalmva and shown to demonstrate potent inhibitory activity toward both DNA repaircompetent and DNA repair-deficient strains of the yeast, Saccharomyces cerevisiae.The compound ( 1 ) synthesized from Dglucosamine has been reported6 to be neuraminidase inhibitor.A common skeleton of