- A tropylium annulated N-heterocyclic carbene
-
Derivatives of the cationic tropylium annulated imidazolylidene ITrop+ are obtained by hydride abstraction from related cycloheptatriene compounds. Spectroscopic, structural and theoretical data indicate that, as a cationic relative of benzimidazolylidenes, ITrop+ has highly reduced σ-donor and strong π-acceptor character.
- Appel, Sebastian,Brüggemann, Peter,Ganter, Christian
-
supporting information
p. 9020 - 9023
(2020/08/17)
-
- Efficient synthesis of trisimidazole and glutaric acid bearing porphyrins: Ligands for active-site models of bacterial nitric oxide reductase
-
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.
-
p. 923 - 926
(2007/10/03)
-
- Regiospecific Synthesis of the Aminoimidazoquinoxaline (IQx) Mutagens from Cooked Foods
-
A versatile regiospecific synthesis has been developed to prepare the six dimethyl- and trimethyl-substituted 2-aminoimidazoquinoxaline (IQx) regioisomers 35, 36, 37, 38, 39, and 40 for complete and unambiguous characterization.The key reaction step in the synthetic sequence for these angular tricycles is a photodehydrohalogenative cyclization of suitably substituted pyrazinylimidazolylethylene intermediates derived from common pyrazine and fully functionalized imidazole precursors.The reaction sequence developed allows for versatility in the substitution pattern as well as total regioisomeric control for the synthesis of all possible methyl and polymethyl analogues of IQx.Comparison of the physical properties among the isomeric di- and trimethyl-IQx's has established the value of unambiguous regiospecific synthesis for structural assignments in this food mutagen series.
- Bierer, Donald E.,O'Connell, John F.,Parquette, Jon R.,Thompson, Charles M.,Rapoport, Henry
-
p. 1390 - 1405
(2007/10/02)
-
- Convenient Synthesis of Methyl 1-Methyl-2,4-dibromo-5-imidazolecarboxylate
-
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
-
p. 767 - 771
(2007/10/02)
-
- 1-ALKYL- AND 1-GLUCOSYL-4,5-IMIDAZOLEDICARBOXAMIDES
-
Among 4,5-imidazoledicarboxamides compounds were found which possess clearly defined neurotropic activity.In order to study the relation between the structure and the activity a series a new 4,5-imidazoledicarboxamides substituted in the amide groups and at the nitrogen of the imidazole ring were obtained.Their syntheses and characteristics are described.
- Aleksandrova, I. Ya.,Khrustaleva, V. S.,Khromov-Borisov, N. V.
-
p. 364 - 367
(2007/10/02)
-