Asymmetric Catalytic 2,3 Stevens and Sommelet–Hauser Rearrangements of α‐Diazo Pyrazoleamides with Sulfides

Abstract Catalytic enantioselective 2,3 Stevens and Sommelet–Hauser rearrangements of α‐diazo pyrazoleamides with sulfides were achieved by utilizing chiral N , N ′‐dioxide/nickel( II ) complex catalysts. These rearrangements proceeded well under mild reaction conditions, providing rapid and facile access to a series of functionalized 1,6‐dicarbonyls or sulfane‐substituted phenylacetates with high to excellent enantioselectivities. The catalytic system shows excellent stereocontrol, discriminating between the heterotopic lone pairs of sulfur and controlling both the 1,3‐proton transfer and the 2,3‐σ rearrangement.