Synthesis of [6]helicene-based sulfonic acid, sulfonamide, and disulfonimides

Abstract The synthesis of helically chiral [6]helicene-based sulfonic acid and sulfonamide from enantiomerically pure 1-acetylthio-5,6,9,10-tetrahydro[6]helicene is reported. The first helically chiral disulfonimides were developed as a synthetic application of [6]helicene-based sulfonamide. This new class of organocatalysts was tested in an asymmetric Mukaiyama aldol reaction to obtain up to quantitative yields and enantioselectivities up to 24%.