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

Abstract

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, 1 H-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 CDCl 3 , 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.

Ultrasound-assisted and Efficient Knoevenagel Condensation Reaction Catalyzed by Silica Sodium Carbonate Nanoparticles

“…Over the past few decades, several methods have been proposed and developed by chemists for Knoevenagel condensation reactions. For instance, running the reaction in the presence of Lewis acids or bases, [12,13] ionic liquids, [14] green solvents, [15] microwave assistance, [16] ultrasound irradiation, [17] solid-phase reactions, [18] grinding methods, [19] solvent-free microwave assisted conditions, [20] and using biocatalysts, [15,21] organocatalysts [22] or polyoxometalates [23] could be countered as these methodologies. Furthermore, there are a few reports that have been applied to Knoevenagel condensation under different conditions including continuous flow synthesis, [24] or fluorous biphasic system.…”