A new type of axially
chiral sulfonic acid was developed.
The synthesis
is based on cheap commercially available materials and a practical
method for optical resolution via diastereomeric salt formation, which
can provide both enantiomers. Eleven benzoimidazolylnaphthalenesulfonic
acids were prepared and four of them were isolated as pure and stable
atropisomers. Moreover, several of these sulfonic acids were transformed
into triflyl imides to further expand the range of dissociation constants.