Synthesis of Optically Pure 3,3′-Diaryl Binaphthyl Disulfonic Acids via Stepwise N-S Bond Cleavage

We developed a practical synthesis of optically pure 3,3 '-diaryl-1,1 '-binaphthyl-2,2 '-disulfonic acids (i.e., (R)- or (S)-3,3 '-Ar-2-BINSAs) from the parent chiral sulfonimides via stepwise N-S bond cleavage of the sulfonimides and the resultant sulfonamides. This unusual synthesis, which provides arylsulfonic acids from arylsulfonamides, is valuable since common methods particularly give amines with the decomposition of sulfone groups during deprotection.