Diaryl ureas

Etter, M. C., Z. Urbanczyk-Lipowska, M. Zia-Ebrahimi, and T. W. Pananto. 1990. Hydrogen Bond Directed Cocrystallization and Molecular Recognition Properties of Diaryl Ureas. J. Am Chem. Soc. 112, 8415. 

Murray, J. S., M. E. Grice, P. Politzer, and M. C. Etter. 1991a. A Computational Analysis of Some Diaryl Ureas in Relation to Their Observed Crystalline Hydrogen Bonding Patterns. Mol. Eng. 1, 95. 

Heterocyclic rings can be produced from the reaction of a chalcone 203 under basic conditions with urea or thiourea, generating the corresponding diaryl guanidinium structure 204a or 204b as displayed in Scheme 56 by Kidwai and... 

Symmetrical dialkyl and diaryl thioureas have been prepared in generally good yield (60-90%) from the reaction of the amine with thiophosgene, formed in situ from the catalysed reaction of carbon tetrachloride with sodium sulphide [5], Reaction with diamines yields cyclic ureas. 

In a related three-component reaction procedure, aryl methyl ketones 724 have been combined with aryl aldehydes 725 and urea 726 at room temperature, using trimethylsilyl iodide as catalyst, to give 4,6-diaryl-3,4-dihydro-2(177)-pyrimidinones 727 <2005HCA2996>. A procedure using zinc iodide and microwave irradiation gave similar products <2007T1981>. 

Symmetrical diaryl- or dialkylureas are prepared in good yield by heating the respective primary amines and ureas in the dry state at 160°C [8] or by boiling an aqueous solution of the amine hydrochloride with urea [9, 10]. The reaction is thought to involve the steps shown in Eqs. (7)-(10). 

Aryl cyanides react with the anion of urea (or thiourea) to give the 2,4-diaryl-l,3,5-triazinone (164) in good to excellent yields except when o-chloroaryl isocyanates are used (76JHC917). 

Nitro groups of /n nitro substituted diaryl ureas are not usually used as hydrogen bond acceptors for urea NH hydrogen atoms in the presence of guest molecules with good hydrogen bond acceptors. 

A convenient approach to diaryl C-substituted tetrazocanes 62 involved an acid-catalyzed condensation of urea and l,2-diphenylethane-l,2-dione (Equation 20) <1993MI38>. 

The Beckmann rearrangement of ketoximes to the corresponding amides (31), the Fischer indole cyclization, isomerization of epoxides to the corresponding aldehydes, ketones, or alcohols, hydration and ammo-nolysis of epoxides, oxygen-sulfur interchange, formation of diaryl-ureas and -thioureas from condensation of aniline and carbonyl sulfide, and olefin carbonylation occur over zeolite catalysts (62). The oxo reaction over rhodium and cobalt containing zeolites recently has been claimed (22). 

The relative rates of these reaction sequences were found to depend on the nature of the medium (homogeneous or heterogeneous), rate of addition of water, temperature, reactivity of the amine (formed by the decomposition of the carbamic acid) with the isocyanate, concentration, and other factors. For example, in the reaction with phenyl isocyanate, cold water and heterogeneous medium favored the formation of diaryl urea while with boiling water the main product was aniline. Dilution also favored aniline formation. 

Diaryl ureas. Zeolite HSZ-360 promotes the reaction of arylamines with ethyl... 

The diaryl urea (62)inhibits I-IL-8 binding to CXCR2 on CHO cells (IC50 = 500 nM) (290, 291). A simple incorporation of a bromine on one of the aryl groups (63) provided a marked enhancement in CXCR2 affinity (IC50... 

In an effort to identify an orally active drug, further optimization in the diaryl urea series led to (64), which inhibits I-IL-8 binding to... 

This relatively simple compound 231 requires the 4-C1 picolinic acid chloride 227 easily made in high yield by the S0C12 reaction described earlier. This has the advantage of simultaneously turning the acid into the acid chloride. Formation of the amide 228 and then the diaryl ether is followed by coupling with an isocyanate 230 to make the unsymmetrical urea 231. This large scale synthesis is planned for manufacture.33... 

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