Extremely high regio- and stereoselective C-C bond formation of substituted γ-hydroxylactams: synthesis of macronecines based on their structural duality

With a view to develop a new synthetic entry for the necine bases, treatment of functionalized gamma-hydroxylactams was found to undergo quite high regio- and diastereoselective carbon-carbon bond formation reactions, affording the corresponding structurally dualistic alkylated lactams in satisfactory yields. The reaction was further applied to the practical and efficient synthesis of (+)-macronecine [(1S, 2R, 7aR)-1-hydroxymethyl-2-hydroxypyrrolizidine] and (+)-2-epi-macronecine [(1S, 2S, 7aR)-1-hydroxymethyl-2-hydroxypyrrolizidine]. (C) 2009 Elsevier Ltd. All rights reserved.