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Pyrrolidine ureas

Merritt, (. R. et al. (2009) Novel pyrrolidine ureas as C-C chemokine receptor 1 (CCRl) antagonists. Journal of Medicinal Chemistry, 52, 1295-1301. [Pg.338]

Use of the valine derived (4S )-3-acetyl-4-isopropyl-1,3-oxazolidine (8)92, the C2-symmetric reagents (2.5,55)-l-acetyl-2,5-bissubstituted pyrrolidine 994, or the doubly deprotonated acetyl urea /V-acetyl- V..V -bis[(.S)-l-phcnylethyl]urea (10), also does not lead to sufficient induced stereoselectivity combined with acceptable chemical yield. When the acetyl urea enolate is reacted with aliphatic and aromatic aldehydes, the diastereomeric adducts (ratios ranging from 1 1 to 3 1) may be separated by column chromatography to give ultimately both enantiomers of the 3-hydroxy acids in 99% ee110. [Pg.508]

A bicyclic urea (123) was an unexpected product of the reaction between pyrrolidine and the phenyl ester of 2-cyano-l,4,5,6-tetrahydro-l-pyridinecarboxylic acid (124 R = Ph) the corresponding methyl ester (124 R = Me) reacted, as expected, to give the product of Michael addition (125). ° The better leaving ability of phenoxide vs methoxide presumably tilted the reaction towards the substitution rather than the addition product, although thiols (e.g. PhSH) underwent only the addition reaction. [Pg.56]

Ornithine is a metabolically quite active amino acid, and the important precursor of pyrrolidine nucleus, which is found in pyrrolizidine alkaloids. Ornithine itself is a non-protein amino acid formed mainly from L-glumate in plants, and synthesized from the urea cycle in animals as a result of the reaction catalyzed by enzymes in arginine. [Pg.73]

Figure 6.61 Bifunctional hydrogen-bonding pyrrolidine-(thio)ureas utilized for Michael reactions of ketones with nitroalkenes. Figure 6.61 Bifunctional hydrogen-bonding pyrrolidine-(thio)ureas utilized for Michael reactions of ketones with nitroalkenes.
The results show that a number of ruthenium carbonyl complexes are effective for the catalytic carbonylation of secondary cyclic amines at mild conditions. Exclusive formation of N-formylamines occurs, and no isocyanates or coupling products such as ureas or oxamides have been detected. Noncyclic secondary and primary amines and pyridine (a tertiary amine) are not effectively carbonylated. There appears to be a general increase in the reactivity of the amines with increasing basicity (20) pyrrolidine (pKa at 25°C = 11.27 > piperidine (11.12) > hexa-methyleneimine (11.07) > morpholine (8.39). Brackman (13) has stressed the importance of high basicity and the stereochemistry of the amines showing high reactivity in copper-catalyzed systems. The latter factor manifests itself in the reluctance of the amines to occupy more than two coordination sites on the cupric ion. In some of the hydridocar-bonyl systems, low activity must also result in part from the low catalyst solubility (Table I). [Pg.183]

A quantitative kinetic model of the polymerization of a-pyrrolidine and cyclo(ethyl urea) showed,43 that two effects occur the existence of two stages in the initiation reaction and the absence of an induction period and self-acceleration in a-pyrrolidine polymerization. It was also apparent that to construct a satisfactory kinetic model of polymerization, it was necessary to introduce a proton exchange reaction and to take into consideration the ratio of direct and reverse reactions. As a result of these complications, a complete mathematical model appears to be rather difficult and the final relationships can be obtained only by computer methods. Therefore, in contrast to the kinetic equations for polymerization of e-caprolactam and o-dodecalactam discussed above, an expression... [Pg.33]

F. (S)-f-)-l-Amino-S-methoxymethy1,pyrrolidine (SAMP). A 4-L, threenecked flask containing the crude urea 1s cooled to -5°C (internal temperature) by means of an ice-salt bath and treated with a chilled (-5°C) solution of 168 g of potassium hydroxide in 150 nt of water. After addition of 685 mL (1.3 mol) of 1.9 N potassium hypochlorite solution (Note 15), precooled to -5°C, the temperature rises within 10 min to 30-40°C and the cooling bath is removed after the mixture reaches room temperature (Note 16). Stirring is... [Pg.97]

The efficient catalytic cyclization (aminocarbonylation) of A-(3-hydroxy-4-pentenyl)amides and carbamates in acetic acid gave m-fused bicyclic pyrrolidine lactone compounds54,56 (Table 2), in agreement with the observed ra-directing capability of the hydroxy group in analogous electrophile mediated additions (Section 7.2.6). In tetrahydrofuran the reaction rate is unacceptably low. In methanol a competitive allylic substitution leads to 1,2,5,6-tetrahydropyridines. Furthermore, lower yields were obtained in the cyclization of the corresponding ureas. [Pg.873]

Other CCR3-specific antagonists are characterized by the piperidine ureas (31-33), and the di-substituted pyrrolidine (34) (158). Again, a basic nitrogen, capable of protonation at physiologic pH, appears to be a common feature. It is important to note that the quaternary ammonium salt (32)demonstrates enhanced potency, relative to that of its parent (31) in binding, chemotaxis, and a whole-blood GAFS assay (Table 4.8) (159). [Pg.150]

Koehn, U., Guenther, W., Goerls, H. and Anders, E. (2004) Preparation of chiral thioureas, ureas and guanidines from (S)-2-(7V,7V-dialkylaminomethyl)pyrrolidines. Tetrahedron Asymmetry, 15,1419-1426 Koehn, U., Schulz, M., Goerls, H. and Anders, E. (2005) Neutral zinc (II) and molybdenum(O) complexes with chiral guanidine ligands synthesis, characterisation and applications. Tetrahedron Asymmetry, 16, 2125-2131. [Pg.142]


See other pages where Pyrrolidine ureas is mentioned: [Pg.52]    [Pg.160]    [Pg.322]    [Pg.1437]    [Pg.52]    [Pg.160]    [Pg.322]    [Pg.1437]    [Pg.138]    [Pg.397]    [Pg.514]    [Pg.77]    [Pg.109]    [Pg.262]    [Pg.53]    [Pg.46]    [Pg.167]    [Pg.60]    [Pg.72]    [Pg.75]    [Pg.979]    [Pg.596]    [Pg.324]    [Pg.645]    [Pg.225]    [Pg.338]    [Pg.339]    [Pg.35]    [Pg.409]    [Pg.249]    [Pg.86]    [Pg.53]    [Pg.117]    [Pg.670]    [Pg.31]    [Pg.479]    [Pg.278]    [Pg.3285]    [Pg.281]   
See also in sourсe #XX -- [ Pg.325 , Pg.326 ]




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Pyrrolidine-(thio)urea Catalysis

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