Pentafluorophenyl sulfonate ester as a protecting group for the preparation of biaryl- and heterobiaryl sulfonate esters

The use of the pentafluorophenyl (PFP) group as a sulfonic acid protecting group has allowed the synthesis of new biaryl- and heterobiaryl-PFP-sulfonate esters by use of the Suzuki-Miyaura reaction. The successful employment of a novel inorganic base, anhydrous sodium tetraborate, was crucial to give the products in excellent yields. The PFP-sulfonate ester has been previously shown to be an excellent alternative to sulfonyl chlorides in the synthesis of sulfonamides. structure: see text]