In an endeavor to improve the copper saltcatalyzed reactions, dichloromethane was replaced with nitroethane and the rearrangement was tried with three copper salts. The yields were also excellent and in each case the rate of reaction was increased, indicating that nitroethane is also an excellent medium for the copper salt-catalyzed sigmatropic rearrangement of propargylic sulfinates to allenic sulfones (Table 5,
entries 14–16).