Diastereoselective Brook rearrangement-mediated [3+4] annulation: application to a formal synthesis of (+)-laurallene.

The formal synthesis of (+)-laurallene, a halogenated eight-membered ring ether, was accomplished. The synthesis involves construction of a trans alpha,alpha'-disubstituted oxocene structure 16 through a Brook rearrangement-mediated [3+4] annulation using acryloylsilane 10 and 6-oxa-2-cycloheptenone 9 and its conversion into 2, which has been transformed into (+)-laurallene by Crimmins and co-workers.