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 a-diazo pyrazoleamides with sulfides were achieved by utilizing chiral N,N'-dioxide/nickel-( II )c omplex catalysts.T hese rearrangements proceeded well under mild reaction conditions,p roviding rapid and facile access to aseries of functionalized1,6-dicarbonyls or sulfanesubstituted phenylacetates with high to excellent enantioselectivities.T he 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]-s rearrangement.Scheme 1. Sulfur-containing drugs and catalytic asymmetric [2,3] sigmatropic rearrangements.