Synthesis of ZIF-67- Effect of solvent on the structure

In the present paper, ZIF-67 material was synthesized from cobalt (II) nitrate hexahydrate and 2-methyl imidazole in three different solvents (methanol, ethanol and acetone) at room temperature. The obtained samples were characterized using XRD, SEM, FTIR, TGA and nitrogen adsorption/desorption measurements. The results show that the synthesized ZIF-67 materials had a high purity, nano-size, and uniformity with the sharp dodecahedrons structure of ZIF-67. Solvents had an influence on the size and nature of the ZIF-67 crystal. The average crystalline size of the nanoparticles calculated by Scherrer equation were 64 nm for sample in acetone solvent, 128 nm for sample in ethanol solvent and 132 nm for sample in methanol solvent. The obtained samples had high thermal stability ( 320 °C). The ZIF-67 material with ethanol solvent had a high specific surface area (SBET) of 1506 m2/g. The synthesized samples exhibited better adsorption capacity of methyl oranges than that of rhodamine B.

Chemistry of Spontaneous Alkylation of Methimazole with 1,2-Dichloroethane

Spontaneous S-alkylation of methimazole (1) with 1,2-dichloroethane (DCE) into 1,2-bis[(1-methyl-1H-imidazole-2-yl)thio]ethane (2), that we have described recently, opened the question about its formation pathway(s). Results of the synthetic, NMR spectroscopic, crystallographic and computational studies suggest that, under given conditions, 2 is obtained by direct attack of 1 on the chloroethyl derivative 2-[(chloroethyl)thio]-1-methyl-1H-imidazole (3), rather than through the isolated stable thiiranium ion isomer, i.e., 7-methyl-2H, 3H, 7H-imidazo[2,1-b]thiazol-4-ium chloride (4a, orthorhombic, space group Pnma), or in analogy with similar reactions, through postulated, but unproven intermediatethiiranium ion 5. Furthermore, in the reaction with 1, 4a prefers isomerization to the N-chloroethyl derivative, 1-chloroethyl-2,3-dihydro-3-methyl-1H-imidazole-2-thione (7), rather than alkylation to 2, while 7 further reacts with 1 to form 3-methyl-1-[(1-methyl-imidazole-2-yl)thioethyl]-1H-imidazole-2-thione (8, monoclinic, space group P 21/c). Additionally, during the isomerization of 3, the postulated intermediate thiiranium ion 5 was not detected by chromatographic and spectroscopic methods, nor by trapping with AgBF4. However, trapping resulted in the formation of the silver complex of compound 3, i.e., bis-{2-[(chloroethyl)thio]-1-methyl-1H-imidazole}-silver(I)tetrafluoroborate (6, monoclinic, space group P 21/c), which cyclized upon heating at 80 °C to 7-methyl-2H, 3H, 7H-imidazo[2,1-b]thiazol-4-ium tetrafluoroborate (4b, monoclinic, space group P 21/c). Finally, we observed thermal isomerization of both 2 and 2,3-dihydro-3-methyl-1-[(1-methyl-1H-imidazole-2-yl)thioethyl]-1H-imidazole-2-thione (8), into 1,2-bis(2,3-dihydro-3-methyl-1H-imidazole-2-thione-1-yl)ethane (9), which confirmed their structures.

Synthesis and Antimicrobial Activities of 1-((5-Chloro-1-ethyl-2-methyl-1H-imidazol-4-yl)sulfonyl)-N-ethylpyrrolidine-2-carboxamide

A new 1-((5-chloro-1-ethyl-2-methyl-1H-imidazol-4-yl)sulfonyl)-N-ethylpyrrolidine-2-carboxamide was synthesized from methyl-1-[(5-chloro-1-ethyl-2-methyl-1H-imidazol-4-yl)sulfonyl]pyrrolidine-2-carboxylate and ethylamine. The compound methyl-1-[(5-chloro-1-ethyl-2-methyl-1H-imidazol-4-yl)sulfonyl]pyrrolidine-2-carboxylate was synthesized from methyl pyrrolidine-2-carboxylate and 5-chloro-4-chlorosulfonyl-1-ethyl-2-methyl-imidazole. The compounds were characterized based on FTIR, 1H, 13C NMR, and DEPT 135 analysis. Antimicrobial activities of the 1-((5-chloro-1-ethyl-2-methyl-1H-imidazol-4-yl)sulfonyl)-N-ethylpyrrolidine-2-carboxamide against Gram-positive (methicillin-susceptible Staphylococcus aureus, methicillin-resistant Staphylococcus aureus, and Bacillus subtilis), Gram-negative (Pseudomonas aeruginosa, Escherichia coli, Klebsiella pneumoniae), and Candida albicans were carried out using the standard microbiological method. The newly synthesized 1-((5-chloro-1-ethyl-2-methyl-1H-imidazol-4-yl)sulfonyl)-N-ethylpyrrolidine-2-carboxamide had no activities against the tested organisms. Keywords: 1-((5-chloro-1-ethyl-2-methyl-1H-imidazol-4-yl)sulfonyl)-N-ethylpyrrolidine-2-carboxamide; methyl-1-[(5-chloro-1-ethyl-2-methyl-1H-imidazol-4-yl)sulfonyl]pyrrolidine-2-carboxylate; L-proline; ethylamine.

Strecker Synthesis of α-aminonitriles Facilitated by N-methyl Imidazolium Acetate

N-Methyl imidazolium acetate [HMIm]OAc was simply prepared through reaction of N-methyl imidazole with acetic acid and it was applied as a media and promoter for Strecker synthesis of α-aminonitriles. The three component reaction of a variety of structurally different aldehydes and amines with trimethylsilyl cyanide (TMSCN) in the presence of [HMIm]OAc were evaluated. Reaction of aromatic aldehydes and cinnamaldehyde with either aromatic and aliphatic amines provided the corresponding α-aminonitriles in high to excellent isolated yields after short period of time at room temperature.

Concise Synthesis of Both Enantiomers of Pilocarpine

Furan-2-carboxylic acid was used as a starting material for the synthesis of dehydro-homopilopic acid. Esterification, hydrogenation and enzymatic hydrolysis followed by the reduction of Weinreb amides and a single-step attachment of a 1-methyl-imidazole residue allowed for the concise synthesis of both enantiomers of pilocarpine.

Facile Access to 2-Substituted Benzoxazoles Using Sawdust Supported N-Heterocyclic Carbene-Ni Complex via C-H Activation

Sawdust supported N-heterocyclic carbene-nickel complex has been prepared by covalent grafting of 1-methyl imidazole in the matrix of chloropropyl modified sawdust followed by reaction with nickel acetate. The resultant NHC-Ni complex was employed as a heterogeneous catalyst for the synthesis of 2-substituted benzoxazoles from benzoxazole and aryl boronic acids following C-H activation strategy. The recycling experiments showed that the complex could be reused for five consecutive runs without significant loss in the yield of products.

Pd(0)-Catalyzed Direct Inter- and Intramolecular C–H Functionalization of 4-Carboxyimidazoles

The palladium-catalyzed arylation and alkenylation of N-substituted methyl imidazole-4-carboxylates are described through inter- and intramolecular pathways. Both direct C2–H and C5–H arylation and alkenylation proceed under Pd(0)/Cu(I) cooperative catalysis and Pd(0) catalysis, respectively, in low-polarity 1,4-dioxane solvent. The methodology gives access to C2 (hetero)aryl or alkenyl imidazoles as well as innovative C2- and C5-arylated fused imidazoles tricycles with a five- to seven-membered middle ring.