Chiral atropisomeric diiodobiphenyls––enantiodifferentiation by the dirhodium method

Abstract

Enantiodifferentiation of atropisomeric biphenyl diiodides can easily be accomplished by adding the enantiopure dirhodium complex Rh* as an NMR auxiliary, although iodine is only a weak donor in forming adducts with Rh*. Further Lewis-base substituents X/X′ (e.g., NH 2 or SH) may dominate the adduct formation equilibria whereas others are hardly involved (e.g., Cl, OCH 3, NMe 2, and OH).