The [2,3]-sigmatropic rearrangement of propargylic sulfonates to allenic sulfones and further applications to oxacycles and dihydrofuranones

Abstract

[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT AUTHOR'S REQUEST.] The scope of [2,3]-sigmatropic rearrangement of propargylic sulfinates to allenic sulfones by silver catalysis was expanded. A series of new propargylic sulfinate esters was generated from a variety of aromatic and heteroaromatic sulfonyl chlorides and their rearrangement to allenic sulfones is reported. In addition, the synthesis of propargylic sulfinate esters containing electron-withdrawing benzenesulfonyl chlorides was optimized and reported. In the course of pursuing a Nazarov cyclization of allenyl vinyl ketones (AVK), we discovered multiple new reactions. Allenyl alcohols underwent an intramolecular cyclization to 2,5-dihydrofurans in the presence of Fetizon's reagent and this process was then optimized using silver fluoride. The methodology was expanded to synthesize higher membered oxacycles also. A tandem cyclization of hydroxypropargylic sulfinate esters to 2,5-hydrofurans was also developed. A new synthesis of a'-hydroxyenones was developed by the oxidation of a-allenyl alcohols with Cr (VI) regents and then extended to synthesize dihydrofuran- 3(2H)-ones by acid catalysis.