Efficient Synthesis of Imidazoles from Aldehydes and 1,2-Diketones Using Microwave Irradiation

Gold- and iodine-mediated internal oxygen transfer of nitrone- and sulfoxide-functionalized alkynes

Intramolecular oxygen transfer of nitrone- and sulfoxide-alkynes was achieved using a catalytic amount of Au(I) and a stoichiometric amount of iodine. The Au(I)-catalyzed cyclization of a nitrone-terminal alkyne afforded a cyclic iminoester, while cyclization of analogous nitrone-internal alkynes yielded aldehyde-enones. The I(2)-mediated cyclization of nitrone-alkynes afforded iodinated γ-lactams and the I(2)-mediated internal redox of the closely related sulfoxide-alkynes gave diketones functionalized with a thoiether.

Practical multi-component synthesis of di- or tri-aryl (Heteraryl) substituted 2-(pyridin-2-yl)imidazoles from simple building blocks

A convenient and highly efficient multicomponent protocol has been developed for the synthesis of various poly-substituted 2-(pyridin-2-yl)imidazoles from 2-cyanopyridine, corresponding aromatic aldehydes, and NH(4)OAc/primary amine. Notably, tri-substituted 2-(pyridin-2-yl)imidazoles were highly yielded when aromatic primary amines were used as substrates, but both di- and tri-substituted 2-(pyridin-2-yl)imidazoles were obtained in one pot when some aliphatic primary amines were used as substrates.

Microwave-assisted, solvent-free and parallel synthesis of some novel substituted imidazoles of biological interest

Solvent free microwave assisted synthesis of some novel substituted imidazoles of biological interest is reported. First, primary aromatic or heteryl amine was condensed with aryl or heteryl aldehydes to afford corresponding Schiff's base. The Schiff's base further on treatment with ammonium acetate (NH(4)OAC) and isatin using silica gel as the solid support, yielded the corresponding aryl imidazoles. In this paper a comparative study between the developed microwave method and conventional method is described. The synthesized compounds were analyzed by physical and analytical data. The synthesized compounds were evaluated for their antibacterial, anthelmintic, short-term anticancer and antitubercular activity. All the synthesized substituted imidazoles have shown good antibacterial activity against gram negative bacterial strains Klebsiella pneumoniae and Escherichia coli and moderate to good anthelmintic activity. The synthesized imidazole derivative possessed significant cytotoxic activity against Ehrlich's ascites carcinoma (EAC) cell lines. None of the compounds exhibited prominent antitubercular activity.

One-Pot Synthesis of Imidazole-4-Carboxylates by Microwave-Assisted 1,5-Electrocyclization of Azavinyl Azomethine Ylides

Diversely functionalized imidazole-4-carboxylates were synthesized by microwave-assisted 1,5-eletrocyclization of 1,2-diaza-1,3-diene-derived azavinyl azomethine ylides. 1,2-Diaza-1,3-dienes were treated with primary aliphatic or aromatic amines and subjected to microwave irradiation in the presence of aldehydes. 3-Alkyl- and 3-arylimidazole-4-carboxylates were prepared in good yields through a one-pot multicomponent procedure. Modulation of the substituents at C-2, N-3 and C-5 was possible, and 2-unsubstituted imidazoles were obtained when paraformaldehyde was used.

Ionic liquid [EMIM]OAc under ultrasonic irradiation towards the first synthesis of trisubstituted imidazoles

The ionic liquid 1-ethyl-3-methylimidazole acetate ([EMIM]OAc) was found to be a mild and effective catalyst for the efficient, one-pot, three-component synthesis of 2-aryl-4,5-diphenyl imidazoles at room temperature under ultrasonic irradiation. This procedure has many obvious advantages compared to those reported in the previous literatures, including avoiding the use of harmful catalysts, reacting at room temperature, high yields, simplicity of the methodology.

1-[2-(Benzyl-amino)-4-pyrid-yl]-2-(4-fluoro-phen-yl)ethane-1,2-dione

The crystal structure of the title compound, C(20)H(15)FN(2)O(2), contains two crystallographically independent mol-ecules, which are related by a pseudo-inversion center and linked into dimers via inter-molecular N-H⋯N hydrogen bonds. The 4-fluoro-phenyl ring of mol-ecule A makes dihedral angles of 17.17 (16) and 62.25 (15)°, respectively, with the phenyl and pyridine rings. The 4-fluoro-phenyl ring of mol-ecule B makes dihedral angles of 8.50 (16) and 64.59 (15)°, respectively, with the phenyl and pyridine rings. The dihedral angle between the pyridine ring and the phenyl ring of mol-ecule A [60.97 (15)°] is bigger than in mol-ecule B [59.49 (15)°]. The dihedral angle between the two pyridine rings is 1.37 (14)° and between the two phenyl rings is 3.64 (16)°.