Synthesis of the C/D/E-ring core compound of maoecrystal V

Maoecrystal V is a highly oxidized and rearranged norterpenoid isolated from the Chinese herb, Isodon eriocalyx. A synthetic route for C/D/E-ring core compound of maoecrystal has been developed. Introduction C1 fragment to D/E-ring was achieved by lithito dithiane attack, C-ring formed deprotective intramolecular hemiacetalization dithiane-alcohol precursor.