Total synthesis of (−)-δ-lycorane

Abstract

The total synthesis of (−)-δ-lycorane is reported. We performed organocatalytic Mannich reaction between phenylacetaldehyde and γ-hydroxy lactam to construct a 5-substituted-2-pyrrolidone derivative in favor of the cis-isomer. Furthermore, diastereoselective conjugate addition to α,β-unsaturated lactam was accomplished to obtain 4,5-disubstituted-2-pyrrolidone. The other salient features of this synthesis include Bischler–Napieralski reaction and ring closing metathesis.