Intramolecular Hydrogen Bonding in 2,3-Bis-(3,4-dimethoxybenzoyl)Propionitrile

3,4-Dimethoxybenzoylacetonitrile, required in the synthesis of some isoxazole derivatives, was obtained from α-bromoacetoveratrone and potassium cyanide. In this reaction, a byproduct could be isolated. From its IR, 1H-NMR, MS and elemental analysis data, it was identified as 2,3-bis-(3,4-dimethoxybenzoyl)propionitrile. A careful study of its NMR spectrum revealed the existence of two intramolecular weak hydrogen bonds, in solution in CDCl3, of the type C-H---O=C. Paramagnetic shifts, Δδ, of 0.5 and 1 ppm, were found for the hydrogens involved in the interactions, as well as significant differences in the coupling constants. A molecular model confirmed the findings made by the conformational analysis. Thus, the secondary structure of the title compound was established.