Pd‐Catalyzed Regio‐ and Stereoselective Ring‐Opening Hydrosulfonylation of Methylenecyclopropanes for Branched Allylic Sulfones

A Pd‐catalyzed ring‐opening hydrosulfonylation reaction of methylenecyclopropanes with sulfonyl hydrazides was developed, which produced a series of branched ( E )‐allylic sulfones in 52−91% yields. In addition, the asymmetric variant was also investigated, and the optically active products were obtained in moderate yields with good enantioselectivities (up to 94:6 er). Mechanistic studies suggested that the reaction proceeds through the formation of an allyl hydrazine intermediate and subsequent rearrangement to the branched ( E )‐allylic sulfone products. Generally, the reaction was completed in one pot under mild reaction conditions, which also featured in good functional group tolerance, broad substrate scope, high regiospecificity, branched selectivity, as well as atom and step economy.