Total Synthesis of (-)-Coriolin

Article abstract of DOI:10.1021/ja00274a050

The first total synthesis of the diterpene coriolin in the enantiomerically pure (-)-form is described.The key step is the photocemical generation of the 3,3,6-trimethyltricyclo<3.3.0^2,8>octane-4,7-dione building blocks (-)-12a and (-)-12b in solutions of exceptionally high concentrations (>/=20 percent).It involves the site selective oxadi-?-methane rearrangement of one β,γ-enone partial chromofore of the β,γ-unsaturated ε-diketones (-)-9a and (-)-9b which are obtained from bicyclo<2.2.2.>oct-7-ene-2,5-dione, (+/-)-7, by optical resolution, in multigram batch preparations, via the tartarate monoacetals followed by trimethylation. (-)-coriolin is thus accessible in 14 steps from (+/-)-7.