Recent Progress on Rearrangements of Sulfones

Abstract

The present review surveys the main literature reports on rearrangements of sulfones published during the last decade. The report concentrates on the three most studied rearrangements, namely, 1,3-sulfonyl migration, Ramberg-Bäcklund rearrangement and pinacol-reduction rearrangement. Both mechanistic aspects and synthetic applications have been emphasized. The first type of rearrangements has been found to occur by both free radical as well as ionic mechanism. A number of synthetic applications, including intramolecular rearrangement-cyclization and regioselective alkene synthesis have been described. With regard to Ramberg-Bäcklund rearrangement, it is of special interest to note the novel isolation of previously postulated episulfone intermediate, and the renewed interest in this type of rearrangement as well as its various important modifications. Due to the novel developments a number of synthetic applications have been described, including preparation of various natural products, novel electrically conducting materials, and enediynes. The last rearrangement is of interest no only due to its mechanistic aspects, but also because it provides the possibility of ring enlargement of cyclic ketones.

Key Words:

• Pinacol-reduction rearrangement
• ramberg-Bäcklund rearrangement
• sulfones
• 1,3-sulfonyl migration