Formal Total Syntheses of (+)-Prelaureatin and (+)-Laurallene by Diastereoselective Brook Rearrangement-Mediated [3 + 4] Annulation

The formal syntheses of (+)-prelaureatin (1) and (+)-laurallene (2), halogenated eight-membered-ring ethers, are described. The key step of our strategy relies on diastereoselective construction of a trans-alpha,alpha'-disubstituted oxocene structure through a Brook rearrangement-mediated [3 + 4] annulation with acryloylsilane 9 and 6-oxa-2-cycloheptenone derivative 22'.