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.