NUCLEAR MAGNETIC RESONANCE AND INFRARED STUDIES OF ACYLATED IMIDAZOLIDINONES AND IMIDAZOLIDINETHIONES
Citations Over TimeTop 18% of 1965 papers
Abstract
The infrared and nuclear magnetic resonance spectra of 1-acyl and 1,3-diacyl derivatives of 2-imidazolidinones and 2-imidazolidinethiones were determined, where the acyl groups were acetyl, benzoyl, or trifluoroacetyl. The frequency of the ring carbonyl stretching vibration increases with the degree of acylation and the electron-withdrawing power of the acyl group. The methylene protons of the diacylated derivatives show a single peak, the paramagnetic shift of which is similarly dependent on these parameters when the ring current effects are allowed for. This correlation between the ν C=O and [Formula: see text] favors the conclusion that the anisotropy of the acyl carbonyl group does not affect the relative methylene proton shift in these compounds and hence they all have the same preferred configuration. This was deduced to be the planar trans,trans structure with respect to the carbonyls. In the unsymmetrical 1,3-diacyl compounds the methylene protons are also nearly equivalent, the τ-value being the average of those for the symmetrical diacyl derivatives. This, together with the changes in the ν C=O (acyl), is explained by mesomeric equalization of the electronic environment of nitrogen atoms 1 and 3. The C=S bond is found to have a strong deshielding influence on all protons.
Related Papers
- → The ammonia dimer: new infrared-far infrared double resonance results(1995)23 cited
- → 1-Acyl-and 1,2-dihydro-1H(acyl)deoxyvasicinones. Synthesis and chemical transformations(2007)5 cited
- → Alkylation and acylation of C-phosphorylated acetamidines involving CH-acidic methylene group(2011)1 cited
- → Acylation of 6,7,8,9-tetrahydro-5H-[1,2,4]triazolo-[4,3-a]azepin-3-ylacetonitrile(2004)1 cited
- → Acylation of 6,7,8,9‐Tetrahydro‐5H‐[1,2,4]triazolo[4,3‐a]azepin‐3‐ylacetonitrile.(2005)