Structure, stereodynamics and absolute configuration of the atropisomers of hindered arylanthraquinones

The substitution of anthraquinone at 1,8 positions by 2-methyl-1-naphthyl groups to yield syn (meso) and anti (racemic) isomers that interconvert with a barrier of 35.4 kcal [mol.sup.-1] in solution is reported. The configurational stability of the atropisomers is attributed to the steric interaction between a single methylnaphthyl substituent and the carbonyl group of the anthraquinone moiety.