Synthesis of casuarine-related derivatives via 1,3-dipolar cycloaddition between a cyclic nitrone and an unsaturated gamma-lactone.

The 1,3-dipolar cycloaddition of the cyclic nitrone derived from tartaric acid and (S)-5-hydroxymethyl-2(5H)-furanone leads to the single adduct 7 which can be transformed into the 3-epi-1-homo-casuarine via a reaction sequence involving reduction of the lactone moiety and N-O bond hydrogenolysis, followed by intramolecular alkylation of the nitrogen atom. The adduct 7 can also be used in the synthesis of 1-methyl- or 3-methyl analogues of 3-epi-casuarine.