Highly efficient [2,3]-sigmatropic rearrangement of sulfur ylide derived from Rh(II) carbene and sulfides in water

Introduction Since their discovery in the late 1960s, the [2,3]-sigmatropic rearrangements of sulfonium ylides have received considerable attention because of their applications in organic synthesis and their probable involvement in biochemical processes. The most common method for sulfonium ylide generation involves the removal of a proton from a sulfonium salt with a strong base. However, a more direct method makes use of the reaction between a carbene (or carbenoid) and a sulfide. Although suitable for ylide formation, carbenes generated photochemically and thermally from diazo compounds are relatively indiscriminate. The potentially more general catalytic approach to carbenoid generation began to evolve with the use of transition metal-catalyzed reactions of diazo compounds. The [2,3]-sigmatropic rearrangement of sulfonium ylides generated from transition metal carbenoids and sulfides, known as the Doyle–Kirmse reaction, is a powerful method for C–C bond formation (Scheme 1). Therefore, many metal catalysts, such as Rh2(OAc)4, Cu(acac)2, [Ru (TTP)(CO)] and dppeFeCl2, were developed to catalyze this reaction. 2,5 However, the Doyle–Kirmse reaction is always performed in dry organic solvent under inert atmosphere due to the high reactivity of the metal carbenoid intermediates. To the best of our knowledge a metal-catalyzed Doyle–Kirmse reaction in water has not been reported. Water, as the most inexpensive and environmentally benign solvent, has been widely used for organic reactions in the past decade. More recently, a few examples demonstrated that the reactions involving metal carbenoid intermediates, such as cyclopropanation, intramolecular C–H insertion and intermolecular N–H insertion of diazo carbonyl compounds, can be carried out in aqueous conditions. Here we report a highly efficient [2,3]-sigmatropic rearrangement of sulfur ylides derived from Rh(II) carbene and sulfides in water.