Ureas, aryl

Tandem mass spectrometry has been used to demonstrate that M+ as well as MH+ of substituted A-(ort/zo-cyclopropylphenyl)benzamides isomerizes before the fragmentation, with formation of 3-aryl-1-ethyl-lH-benzoxazines and 5-ethyl-2-oxodi-benzoazepines (Scheme 5.14). The methyl group in /V-[ortho-( 1 -methylcvclopropyl )-phenyl]benzamides quenches the latter process, leaving the formation of benzoxazines as the only cyclization reaction. A subsequent chemical experiment in solution confirmed the mass spectral predictions [24]. A similar study confirmed the analogy of cyclization of substituted A-(ort/zo-cyclopropylphenyl)-A -aryl ureas and N- ortho-cyclopropylphenyl)-A -aiyl thioureas in the ion source of mass a spectrometer and in solution [25]. 

Substituted ureas are alkylated under solidrliquid phase-transfer catalytic conditions to yield the A -alkylated products to the exclusion of N- and Oalkylated derivatives [23]. Surprisingly, A-aryl ureas do not react under similar conditions. 

Fig. 4 The binding site for sorafenib is illustrated as a Connolly surface, with GluSOl and the displaced DFG sequence explicitly displayed. Hydrogen bonds from the aryl urea moiety are shown with dotted lines...

V-Aryl ureas 51 and 54 react with mesityl oxide 52 [66] or 3-buten-2-one 9 [67] to form thiazines 53 and 55, respectively. But in the second case, alkylation of the hydroxyl group with solvent molecules occurs without dehydration (Scheme 3.16). 

The /V-alkyl and IV-aryl ureas 382 and 383 were prepared in high yield by treatment of 121 with the corresponding isocyanates (Scheme 48).79 The reaction of 382 and 383 with triflic anhydride in pyridine-CH2Cl2 at low temperature produced the respective 2-aminooxazolines 384 and 385 in high yield, with concomitant inversion of stereochemistry at the required position. Complete deprotection of 384 by hydrogenolysis under acidic conditions afforded trehalamine (4). Deprotection of 385 under... 

N-Aryl ureas are converted to the aryldiazonium nitrate upon treatment with NaN02 and H2SO4 in dioxane °° or with DMF—NO2 in DMF. ° ... 

A number of 2-aryl and 2-alkyl derivatives of 5,6-dihydro-1,3-4//-oxazine have been prepared in a similar way.118-120 An analogous reaction consists in thermal cyclization of N- (y-chloropropyl) -A -alkyl and -A -aryl ureas.110-112 121 122... 

HexiEhtcrD-norbornene Aryl-urea Tricyclics Qutntdines... 

Urea herbicides with cycloaliphatic substituents may contain several kinds of cycloalkyl and cycloalkenyl radicals, but only those in which two methyl groups are the substituents on N 1 are of satisfactory activity. A longer alkyl chain reduces herbicidal efficiency, this is also true for aryl urea derivatives. 

The second route yields an end-product of lower purity. The aryl urea intermediate can be prepared at a good yield by the reaction of aniline hydrochloride with urea or of aniline hydrochloride with alkali metal isocyanates ... 

By varying the aryl substituent and the 1-substituents of 3-aryl ureas several effective herbicides have been prepared, such as neburon, l-butyl-3-(3,4-dichlorophenyl)-l-ntethylurea (27) trimeturon, 3-(4-chlorophenyl)-0,l,l-trimethylisourea (28) buturon, 3-(4-chlorophenyl)-l-methyl-1-(1-methylprop-2-ynyl)urea (29) and Proban , 3-(3,4-dichlorophenyl)-l-isopropyl-l-(2-propynyl)-urea (30). Hiose containing unsaturated side-chains include siduron, l-(2-niethyicyclohexyl)-3-phenylurea (31), and methazole, 2-(3,4-dichlorophenyI)-4-methyl-1,2,4-oxa azolidine-2,S-dione (32). 

The microbial degradation of 3-aryl-l,l-dimethylurea herbicides proceeds by stepwise demethylation into 3-aryl ureas, which are then decomposed into aryl amines, carbon dioxide and ammonia according to the following scheme ... 

When two different calixarene tetraureas are mixed together. heterodimers form along with the corresponding homodimers. From a mixture of tetraurea and tetrasul-fonyl urea, heterodimers form exclusively. " The increased acidity of the — SO2NH urea proton may be the reason for sueh selection. The preference of the aryl urea/ sulfonyl urea eould possibly be the basis of a binary molecular code. 

N,N -di aryl ureas have been obtained in good yields from nitroarenes and aminoarenes at 140 C under carbon monoxide <60 atm) in the presence of a catalytic amount of Pt[Pg.162]

A2a11a. Alkyl and aryl ureas A2a11b. Benzthiazureides A2a11c. Sulfonyl ureas... 

An interesting oxidative carbonylation of anihne derivatives was pubhshed in 2009 [37]. The reaction proceeded under 1 bar of CO at room temperature with 5 mol% of [Pd(OTs)2(MeCN)2] as the precatalyst. Either cyclic imidates or methyl anthranilates can be easily generated, depending on the reaction conditions. The use of A -aryl urea derivatives with a terminal N-H moiety allowed for the generation of quinazolinones (Scheme 6.10). 

An interesting Pd-catalyzed diene carboamination reaction that involves urea-directed C—H activation was recently reported [56]. For example, treatment of N-aryl urea 63 with an activated diene in the presence of 10 mol% Pd(0 Ac) 2,50 mol% TsO H, AC2O, and benzoquinone provided 64 in 90% yield (Eq. (1.29)). The transformation is initiated by directed palladation of the arene by a palladium tosylate complex (formed... 

A sequential one-pot synthesis of unsymmetrical aryl urea derivatives was developed by arylation of N-substituted cyanamides under metal-free conditions, followed by a second N-arylation under copper-catalyzed conditions [96]. Chen and Chen devised the arylation of pyridine N-oxides with At21X via initial O-arylation followed by a 1,3-radical rearrangement to o-pyridinium phenolates, and arylation of pyridine N-amidates delivered o-pyridinium anilines (Scheme 5d) [97]. 

Treatment of readily available o-(buta-l,3-diyn-l-yl-)-substituted A -aryl ureas with Au(I) catalyst gives the isomeric pyrimido[l,6-fl]indol-l(2//)-one via a twofold cycliza-tion process (e.g.. Scheme 125). ... 

---