Construction of Sulfonyl Phthalides via Copper-Catalyzed Oxysulfonylation of 2-Vinylbenzoic Acids with Sodium Sulfinates

Copper-catalyzed difunctionalization of 2-vinyl-benzoic acids with sodium sulfinates to construct substituted lactones has been realized. This protocol employs inexpensive CuCl2 as the catalyst, di-tert-butyl peroxide or O-2 as the terminal oxidant, and readily available sodium sulfinates as sulfonylation reagents. High functional group tolerance and excellent yields were demonstrated by the efficient preparation of a wide range of gamma-sulfonylated phthalides.