Synthesis and rearrangement of functionalized dispiro[2.1.3.3]Undecanes - preferred C4C5 over C3C4 ring enlargements

Abstract The functionalized dispiro[2.1.3.3]undecanes 9 and 8 undergo cascade rearrangements to yield the bi- and tricyclic systems 10 , 11 , 12 and 3 , respectively. The rearrangements proceed via an initial enlargement of the four-membered ring.