Enantioselective synthesis of epi-( + )-Sch 642305 : observation of an interesting diastereoselection during RCM

In an approach towards the enantioselective total synthesis of the novel bioactive natural product Sch 642305, an unusual diastereoselection during the key RCM reaction, resulted in the synthesis of the 11-epi-isomer of Sch 642305.