- Efficient synthesis of trisimidazole and glutaric acid bearing porphyrins: Ligands for active-site models of bacterial nitric oxide reductase
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Ligands (1) for active-site models of bacterial nitric oxide reductase (NOR) have been efficiently synthesized. These compounds (1) feature three imidazolyl moieties and one carboxylic acid residue at the FeB site, which represent the closest available synthetic model ligands of NOR active center. The stereo conformations of these ligands are established on the basis of steric effects and 1H NMR chemical shifts under the ring current effect of the porphyrin.
- Collman, James P.,Yan, Yi-Long,Lei, Jianping,Dinolfo, Peter H.
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p. 923 - 926
(2007/10/03)
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- Novel farnesyl protein transferase inhibitors as antitumor agents
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Disclosed are novel tricyclic compounds represented by the formula (1.0): and a pharmaceutically acceptable salt or solvate thereof. The compounds are useful for inhibiting farnesyl protein transferase. Also disclosed are pharmaceutical compositions comprising compounds of formula 1.0. Also disclosed are methods of treating cancer using the compounds of formula 1.0.
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- Synthesis of xestomanzamines a and b
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Synthetic pathways are described for the synthesis of two naturally occurring β-carbolines, xestomanzamine A and B. The synthesis of aromatic xestomanzamine A was most conveniently achieved by way of a Grignard reaction in dichloromethane. This route is suitable for the synthesis of analogues with modifications in the imidazole ring of xestomanzamine A. Xestomanzamine B, an oxidation-sensitive dihydro-β-carboline, was prepared by Pictet-Spengler condensation of tryptamine with a vicinal tricarbonyl substituted imidazole.
- Burm, Brigitte E.A.,Blokker, Peter,Jongmans, Edwin,Van Kampen, Erwin,Wanner, Martin J.,Koomen, Gerrit-Jan
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p. 495 - 503
(2007/10/03)
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- Preparation of 1-alkylimidazoles
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Process for the preparation of 1-alkylimidazoles of the general formula (I) STR1 where R1 is alkyl, R2 and R3 are hydrogen, alkyl, aryl, arylalkyl, or alkylaryl, R4 is carboxy, alkoxycarbonyl R5 OCC--, carbamoyl, or cyano, and R5 is an alkyl of from 1 to 8 carbon atoms--by the reaction of imidazoles of the general formula (II) STR2 with dialkyl sulfates of the general formula (III) at elevated temperatures in the presence of a carboxylic acid or anhydride or of both acid and anhydride.
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- A General Route to 4-Substituted Imidazoles
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Literature routes to di(imidazol-4-yl)methanol (1a) dinitrate and tri(imidazol-4-yl)methanol (2a) trihydrochloride were improved to give 32 and 16percent overall yields, respectively; but we failed to synthesize bis- (1b) and tris-(1-methylimidazol-4-yl)methanol (2b) by the methylation of the corresponding N-methoxymethyl compounds (3; x=2 and x=3).Attempted 4-lithiation of the 1,2,5-protected imidazole (4a) with BuLi-TMEDA failed, giving after hydrolysis 1-methyl-5-trimethylsilylimidazole (4b); similar failures were observed for 2,5-dicarboxy-1-methylimidazole, which after metallation with BuLi-TMEDA and hydrolysis afforded 1-methylimidazole-5-carboxylic acid (5).Our attempts to obtain 4-bromo-1-methylimidazole (10a) and 4-bromo-1-ethylimidazole suitable for a halogen-lithium exchange or for Grignard reaction also failed.Attempted selective lithiation of 2-phenylthio-1-tritylimidazole (16) at the 4-position, then theatment with ethyl formate, led only to a mixture of 4- and 5-substituted products in very low yield, and 1-diethoxymethyl-2-phenylthioimidazole (18) was unstable and difficult to purify. 4-Bromoimidazole with two mol equiv. of t-butyl-lithium gives 1,4-dilithioimidazole, which is now shown to provide a general route to 4-substituted imidazoles.
- Katritzky, Alan R.,Slawinski, Jaroslaw J.,Brunner, Frederic,Gorun, Sergiu
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p. 1139 - 1145
(2007/10/02)
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- Convenient Synthesis of Methyl 1-Methyl-2,4-dibromo-5-imidazolecarboxylate
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Three syntheses of methyl 1-methyl-2,4-dibromo-5-imidazolecarboxylate (8) are presented.One proceeds from sarcosine via ring closure, bromination, and desulfurization.The second uses N-methylimidazole, polybromination, and selective halogen-metal interchange.The third and most efficient and preparatively useful route begins with diaminomaleonitrile (13).Ring closure with triethyl orthoformate followed by methylation and hydrolysis affords 1-methyl-4,5-imidazoledicarboxylic acid (16).Regioselective decarboxylation followed by esterification yields methyl 1-methyl-5-imidazolecarboxylate (18).Subsequent dibromination gives the completely substituted imidazole 8.The primary purification in this sequence is fractional sublimation of 18 after the esterification step.An overall yield of 26percent is achieved from diaminomaleonitrile (13) to methyl 1-methyl-2,4-dibromo-5-imidazolecarboxylate (8), which is a key intermediate for the synthesis of tricyclic imidazo cooked food mutagens.
- O'Connell, John F.,Parquette, Jonathan,Yelle, William E.,Wang, Wilhelm,Rapoport, Henry
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p. 767 - 771
(2007/10/02)
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- Selective Decarboxylation of 1-Methyl-4,5-imidazoledicarboxylic Acid
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The selective decarboxylation of 1-methyl-4,5-imidazoledicarboxylic acid was carried out in various solvents. 1-Methyl-5-imidazolecarboxylic acid was obtained by heating in acetic or propionic anhydride, whereas 1-methyl-4-imidazolecarboxylic acid was obtained in N,N-dimethylformamide, N,N-dimethylacetamide, or N-methylpyrrolidone or by pyrolysis.The reaction mechanism is discussed.
- Takahashi, Kazuyuki,Mitsuhashi, Keiryo
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p. 557 - 558
(2007/10/02)
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