Organocatalytic Michael addition, a convenient tool in total synthesis. First asymmetric synthesis of (-)-botryodiplodin

The asymmetric Michael addition of propionaldehyde to(2E)-(3-nitro-but-2-enyloxymethyl)-benzene 8, catalyzed by the chiral diamine (S,S)-N-iPr-2,2'-bipyrrolidine, afforded, with 93% ee, a precursor 9 of (-)-botryodiplodin. The nitro functionality of 9 was converted to a ketone via a Nef reaction to give, after a few steps, the enantiomerically enriched (-)-botryodiplodin. (C) 2003 Elsevier Ltd. All rights reserved.