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A highly effective catalytic enantioselective direct aminal synthesis was developed. Chiral ammonium 1,1'-binaphthyl-2,2'-disulfonates, which were prepared in situ from (R)-BINSA and achiral amines, promoted the enantioselective addition of primary amides to aromatic aldimines.

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'-Ar2-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.

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