Silver Triflate Catalyzed Cyclopropyl Carbinol Rearrangement for Benzo[<i>b</i>]oxepine and 2<i>H</i>‐Chromene Synthesis

Abstract

Abstract An efficient AgOTf‐catalyzed (TfO = trifluoromethanesulfonate) cyclopropyl carbinol rearrangement for the synthesis of benzo[ b ]oxepines and 2 H ‐chromenes is reported by starting from 2‐[cyclopropyl(hydroxy)methyl]phenols. The reactions proved to be general in scope and furnished a range of the corresponding functionalized oxygen heterocycles. The formation of the benzo‐fused six‐membered adduct is proposed to result from the ring‐contraction of the benzo[ b ]oxepine derivative. Control of the product selectivity is achievable by fine‐tuning the reaction time. The catalytic synergy between the silver(I) cation and the triflate anion was essential for optimal product yields.