Lanthanide-induced shifts of sterically hindered aromatic o-dimethoxy compounds: model compounds and o-dimethoxycoumarins

Abstract

The lanthanide-induced shifts (LIS) of a series of sterically hindered o-dimethoxy compounds, characterized by a 3-substituted 1,2-dimethoxy unit as a structural element, were simulated in model calculations. Development of a generally suitable computational model for aromatic o-dimethoxy compounds allows prediction of relative LIS values for o-dimethoxy complexation. The model was used for several naturally occurring dimethoxycoumarins taking into account the population ratios of the two possible co-ordinating sites in these molecules (o-dimethoxy and lactone carbonyl).