Discoveries and Challenges en route to Swinhoeisterol A.

We here give a full account of our synthetic studies that eventually culminated in the first synthesis of 13(14-->8),14(8-->7) di abeo -steroid swinhoeisterol A as well as the related dankasterones A and B, 13(14-->8) abeo -steroids, and periconiastone A, a 13(14-->8) abeo -4,14-cyclo-steroid. We describe in detail experiments that provided further insight into the mechanism of our switchable radical framework reconstruction approach. By discussing failed strategies and tactics towards swinhoeisterol A, we eventually present the successful route that also allowed an access to structurally closely related analogues as Delta 22 -24- epi -swinhoeisterol A.