| Abstract: | Eu(fod)3 shift reagent was used to simplify PMR spectra from isomeric mono-, di and trimethoxybenzaldehydes. Deshielding gradients, obtained by plotting induced shift vs. molar ratio of Eu(fod)3]/substrate] made it possible to assign methoxyl proton signals to the correct positional substituent in polymethoxylated benzaldehydes. Anomalous upfield shifts for the aldehydic protons of 2,6-dimethoxy- and 2,4,6-trimethoxybenzaldehyde were observed with Eu(fod)3 Various instances of long-range (5J) proton coupling between the aldehydic proton and a meta-proton provide insight to the geometry of the substrate in the complexed state with Eu(fod)3. Di- and trimethoxybenzaldehydes are important precursors for the synthesis of the correspondingly methoxylated amphetamines which are of pharmacological and forensic interest because of abuse and illicit manufacture. |
