A one-pot route toN-acyl ureas: a formal four-component hydrolytic reaction involving aminonitrones and isocyanide dibromides

Abstract

A one-pot route to N-acyl ureas proceeds via generation of electrophilically activated 2-substituted 1,2,4-oxadiazolium salts. The conformation of the N-acyl ureas is stabilized via moderate strength (6.2–7.8 kcal mol−1) resonance-assisted hydrogen bonds.

Predicting the catalytic activity of azolium-based halogen bond donors: an experimentally-verified theoretical study

“…Considering the importance of chemical stability, all oxazolium derivatives were also excluded because the high electrophilicity of these compounds rendered them unstable to reactions with common nucleophiles, including H 2 O. [42][43][44][45] Overall, fourteen structural types of iodoazoliums were evaluated in this study while keeping within these limitations (Fig. 1).…”

“…This level of theory was successfully applied by us in studies of very similar metal-free objects and processes. 41,42 No symmetry restrictions were applied during the geometry optimization procedure. The Hessian matrices were calculated analytically for all optimized model structures (i) to confirm the location of the correct minima or saddle points on the potential energy surface (no imaginary frequencies, or one imaginary frequency, respectively) and (ii) to estimate the thermodynamic parameters (calculated at 25°C) (see Tables S1 and S2 in the ESI †).…”

Novel ferrocene imide derivatives: synthesis, conformational analysis and X-ray structure

“…Recently, a few papers were focused on a conformational analysis of structurally very similar compounds derived from ureas. N -Acyl urea compounds, R–CO−NH−CO−NH−R, when compared to basic imides, R–CO−NH−CO−R, have an additional NH group [ 16 , 17 ]. However, this NH group may form six-membered ring via intermolecular hydrogen bond, N−H···OC, thus initiating very similar relative orientation of the rest of the fragment as reported in cis-trans stereoisomers of imides.…”

A new and facile synthesis of N-benzyl-N′-acylureas via reaction of dibenzoylhydrazine carboxamide and benzylamines

“…[8] N-acylureas were also synthesized recently in a onepot, four-component reaction with very reactive aminonitrones and isocyanide dibromides (Scheme 1e). [9] Figure 1. Some of the N-acylurea derivatives reported to have pharmacological activities.…”

“…Previous synthetic routes for the preparation of N-acylurea derivatives. For reactions a) to e), see references [5] - [9], respectively. Scheme 2.…”