Total Synthesis of (+)-Phyllanthocin. Introduction of Intramolecular Hydroformylation for Complex Molecule Functionalization

Article abstract of DOI:10.1021/jo00294a030

A 17-step total synthesis of (+)-phyllanthocin (1a) is described.Application of Sharpless'asymetric epoxidation reaction provided access to the diastereo- and enantiomerically pure epoxy ketone 9, a partner in crossed aldol construction.A notably rapid and high-yielding spiroketal equilibration leading to the tetracyclic intermediate 2 was effected with HF in acetonitrile.A Rh(I)-catalyzed hydroformylation was used to introduce the C3 functionality.Studies of intramolecular delivery of the rhodium nucleus to the concave face of the C3-C4 olefin led to a substantial improvement in yield and regioselectivity over the intermolecular version.