A General Strategy for the Stereocontrolled Preparation of Diverse 8- and 9-Membered <i>Laurencia</i>-Type Bromoethers

A unique procedure to effect a ring-expanding bromoetherification process is described, wherein tetrahydrofurans and tetrahydropyrans are smoothly transformed into 8- and 9-membered bromoethers in a regio- and stereocontrolled manner through the use of BDSB (bromodiethylsulfonium bromopentachloroantimonate). These products resemble the cores of the <i>Laurencia</i> C15 acetogenins. In light of the generality and effectiveness of the approach, this work provides a unique strategy for their laboratory preparation and may implicate a possible biosynthesis pathway.