Microwave assisted Suzuki-Miyaura and Ullmann type homocoupling reactions of 2- and 3-halopyridines using a Pd(OAc)2/benzimidazolium salt and base catalyst system.

A number of novel benzimidazole derivatives 1-4 were synthesized and the catalytic activity of these compounds in a catalytic system consisting of a benzimidazolium salt/Pd(OAc)2/K2CO3 were investigated in the Suzuki-Miyaura and Ullmann type homocoupling reactions under microwave irradiation. We obtained both cross coupling and homocoupling products of pyridine and some side products such as dimethylaminopyridine and unsubstituted pyridine.

Synthesis, characterization and microwave-promoted catalytic activity of novel N-phenylbenzimidazolium salts in Heck-Mizoroki and Suzuki-Miyaura cross-coupling reactions under mild conditions.

A number of novel benzimidazolium salts having aryl substituents such as N-phenyl, 4-chlorophenyl and various alkyl substituents were synthesized. Their microwave-assisted catalytic activities were evaluated in Heck-Mizoroki and Suzuki-Miyaura cross-coupling reactions using a catalytic system consisting of Pd(OAc)(2)/K(2)CO(3) in DMF/H(2)O under mild reaction conditions with consistent high yields, except those of 2-bromopyridine.

Evaluation of in vitro and in vivo toxic effects of newly synthesized benzimidazole-based organophosphorus compounds.

This paper reports the toxic properties of eight newly synthesized benzimidazole-based organophosphorus (OP) compounds in Xenopus laevis in both in vivo and in vitro conditions. For both experiments, a commercial solution of azinphos methyl (AzM, Gusathion M WP25) was used as a reference compound. The 24-h median lethal concentrations (LC50) of all tested compounds were determined for 46th stage tadpoles in the range of 9.54-140.0 µM. For evaluation of the lethality of the compounds, the activity of the enzyme biomarkers acetylcholinesterase (AChE), carboxylesterase, glutathione S-transferase (GST), glutathione peroxidase, glutathione reductase, lactate dehydrogenase, aspartate aminotransferase, and alanine aminotransferase were determined in vivo in X. laevis tadpoles exposed to three concentrations (LC50, LC50/2, and LC50/4) of tested compounds. All exposure concentrations of AzM and seven of eight tested compounds caused CaE inhibition in in vivo conditions. Furthermore, the AChE inhibition capacity of tested compounds in commercial electric eel AChE and in X. laevis homogenates and also CaE inhibition capacity in only X. laevis homogenates were assayed for a 30-min in vitro exposure period. Eight OP compounds did not inhibit AChE activity more than 23 percent, but AzM exposure inhibited AChE activity by 26 percent for X. laevis homogenates and 97 percent for electric fish AChE in in vitro conditions. Also, CaE inhibition levels in X. laevis tadpole homogenates were 46 percent for AzM and between 8 percent and 33 percent for other compounds in in vitro conditions.

1-{[Dimeth-yl(phen-yl)sil-yl]meth-yl}-3-(2-phenyl-eth-yl)-1H-benzimidazol-3-ium bromide monohydrate.

The title compound, C(24)H(27)N(2)Si(+)·Br(-)·H(2)O, was synthesized from 1-(dimethyl-phenyl-silylmeth-yl)-1H-benzimidazole and (2-bromo-eth-yl)benzene in dimethyl-formamide. The benzimidazole ring system is nearly planar, with a maximum deviation of 0.015 (5) Å, and forms dihedral angles of 73.0 (3) and 39.6 (2)°, with the phenyl rings. In the crystal, mol-ecules are linked by O-H⋯Br, C-H⋯Br and C-H⋯O hydrogen bonds. In addition, the structure features π-π stacking inter-actions, with a face-to-face separation of 3.644 (3) Šbetween parallel benzimidazole ring systems.

Dichloridobis[5-nitro-1-trimethyl-silyl-methyl-1H-benzimidazole-κN]cobalt(II) N,N-dimethyl-formamide solvate.

The title compound, [CoCl(2)(C(11)H(15)N(3)O(2)Si)(2)]·C(3)H(7)NO, was synthesized from 5-nitro-1-trimethyl-silylmethyl-1H-benzimid-azole and cobalt(II) chloride in dimethyl-formamide. The Co(II) atom is coordinated in a distorted tetra-hedral environment by two Cl atoms and two N atoms. In the crystal structure, there are a number of C-H⋯Cl and C-H⋯O hydrogen-bonding inter-actions between symmetry-related mol-ecules.

1-Benzyl-3-[(trimethyl-sil-yl)meth-yl]benzimidazolium chloride monohydrate.

The title compound, C(18)H(23)N(2)Si(+)·Cl(-)·H(2)O, was synthesized from 1-[(trimethyl-sil-yl)meth-yl]benzimidazole and benzyl chloride in dimethyl-formamide. The benzimidazole ring system is approximately planar, with a maximum deviation of 0.022 (2) Å, and makes an angle of 74.80 (12)° with the phenyl ring. The crystal packing is stabilized by O-H⋯Cl, C-H⋯Cl, C-H⋯O and C-H⋯π inter-actions between symmetry-related mol-ecules together with π-π stacking inter-actions between the imidazolium and benzene rings [centroid-centroid distance = 3.5690 (15) Å] and between the benzene rings [centroid-centroid distance = 3.7223 (14) Å].

1-(Prop-2-en-1-yl)-3-[(trimethyl-sil-yl)meth-yl]benzimidazolium bromide monohydrate.

In the title compound, C(14)H(21)N(2)Si(+)·Br(-)·H(2)O, the benzimidazole ring system is almost planar [maximum deviation = 0.021 (2) Å]. In the crystal, O-H⋯Br and C-H⋯O hydrogen bonds link the ions via the O atoms of the water mol-ecules. In addition, there are π-π stacking inter-actions between the centroids of the benzene and imidazole rings of the benzimidazole ring system [centroid-centroid distances = 3.521 (3) and 3.575 (2) Å].

1,3-Difurfurylbenzimidazolium chloride monohydrate.

The title compound, C(17)H(15)N(2)O(2) (+)·Cl(-)·H(2)O, was synthesized from benzimidazole and furfryl chloride in dimethyl-formamide. The cationic benzimidazolium ring is connected to two furan rings via methyl-ene bridges. The furan rings make dihedral angle of 79.09 (18)° with respect to each other, and make dihedral angles of 73.92 (12) and 72.58 (13)° with respect to the benzimidazole ring. O-H⋯Cl, C-H⋯O and C-H⋯Cl hydrogen bonds and C-H⋯π inter-actions contribute to the stabilization of the crystal structure. Furthermore, there is a π-π inter-action between adjacent five- and six-membered rings of the benzimidazole groups [centroid-centroid distance = 3.5305 (8) Å].

1-Cyclo-hexyl-methyl-3-methyl-2-[(phenyl-imino)(sulfido)meth-yl]benzimidazolium.

In the zwitterionic title compound, C(22)H(25)N(3)S, the benzimid-azole ring system makes a dihedral angle of 55.69 (11)° with the phenyl ring. In the crystal structure, inter- and intra-molecular C-H⋯S inter-actions occur.

(E)-1,1'-Bis[(E)-but-2-en-yl]-3,3'-(propane-1,3-di-yl)bis-(1H-benzimidazol-3-ium) dibromide monohydrate.

The title compound, C(25)H(30)N(4) (2+)·2Br(-)·H(2)O, was synthesized from 1,1'-propyl-enedibenzimidazole and (E)-1-bromo-but-2-ene in dimethyl-formamide solution. The two benzimidazole ring systems are essentially planar, with maximum deviations of 0.011 (4) and 0.023 (3) Å. The dihedral angle between these two ring systems is 25.87 (15)°. The crystal structure is stabilized by inter-molecular O-H⋯Br and C-H⋯Br hydrogen-bonding inter-actions. Atmospheric water was incorporated into the crystal structure.