Volume 18, Issue 4

Two novel pyrrole-functionalized bis(benzoimidazolium) salts, which are novel NHC-pyrrole-NHC C-N-C Pincer proligands were synthesized in high yield. Both of these compounds are fully characterized by 1 H and 13 C NMR, IR and elemental analysis.

Synthetic efforts towards new tetracyclic heterocycles bearing the pyrrolo[2′,3′:5,6]azepino[4,3- b ]indol-4(11 H )-one core are described. Synthesized tetracyclic compounds are the first analogs, structurally related to protein kinase inhibitors paullones which incorporate an azepinone, an indole and a pyrrole ring. The synthetic approach involves palladium mediated intramolecular Heck coupling as a key step.

Keto furanylidene building blocks are synthesized from the unique silyl ethers of monoalkynylated β-keto carbonyls. The procedure consists of a desilylation, cyclization, and alkyne hydration facilitated by either a one-pot reaction with iron(III) chloride hexahydrate-iodine or a two-step procedure with tosylic acid and gold(I) chloride. Notably, the hydration of the terminal alkyne with iron(III) chloride hexahydrate-iodine reagent is a safer and new alternative to the use of mercury(II) salts.

A new method for the preparation of perhydro- ­N -(2,2-disubstituted-3-aminopropyl) heterocycles that allows to obtain a large variety of corresponding derivatives with high to moderate yields using simple procedures is described.

Series of 5-substituted arylpyridin-2(1 H )-ones and arylpyrimidin-4(3 H )-ones were designed and synthesized based on pirfenidone, a compound which shows promising therapeutic effects for treatment of fibrosis. The compounds 1a–c , 2a–c and 3a–c were obtained under mild conditions by arylation of the appropriate heterocyclic amines with arylboronic acids under Chan-Lam-Evans conditions. The synthesis of the useful synthon N -(4-methoxyphenyl)-5-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-(1 H )-pyridin-2-one ( 4 ) is also reported. All compounds were characterized by spectral and elemental analysis and structural elucidation by 1 H and 13 C NMR is discussed herein.

The synthesis and characterization of new zinc(II) 3 , nickel(II) 4 and cobalt(II) 5 phthalocyanines complexes carrying macrocyclic N 3 O 2 groups on peripheral positions are described. The compounds were characterized by elemental analysis, IR, 1 H and 13 C NMR, UV-Vis and MS spectral data.

New ciprofloxacin analogs 3a–i were prepared using a conventional methodology and with the help of a microwave irradiation technique. The structures of the synthesized compounds were established on the basis of spectral and analytical data. The antimicrobial activities of newly synthesized compounds were evaluated against a number of microorganisms by using ciprofloxacin as reference. Many of the evaluated compounds exhibit remarkable activities against Gram positive organisms such as Staphylococcus aureus, Streptococci, Bacillus spp., Gram negative organisms such as Escherichia coli, Klebsiella Pneumoniae, Pseudomonas aeruginosa, Salmonella spp., Salmonella typhi and antifungal activity against Candida albicans . Among these, compounds 3a, 3b and 3i exhibit excellent antibacterial activity and products 3c and 3f show very good antifungal activity.

A facile synthesis of new 2,6-bis(5- t -butyl-benzo[ b ]furan-2-ylcarbonyl)pyridines 3a–e is described. The synthesis mainly relies on the ultrasound-assisted Rap-Stoermer reaction of 2,6-bis(bromoacetyl)pyridine ( 1 ) with t -butyl substituted salicylaldehydes 2a–e in MeCN with the presence of PEG-400 as catalyst. This procedure is characterized by short reaction times and good yields.

An efficient and environmentally benign method for the synthesis of 2-substituted benzoxazoles is reported. The condensation of 2-aminophenol with an aldehyde gave an imine intermediate, which was cyclized and dehydrogenated to 2-substituted benzoxazole with good yield in the presence of CeCl 3 /NaI as catalyst. The one-pot synthesis was carried out in toluene at 100°C using O 2 as the oxidant.

3-(3,5-Dimethyl-1 H -pyrazol-1-yl)-3-oxopropanenitrile ( 1 ) was used as a starting material for synthesis of functionalized heterocyclic derivatives mentioned in the title.

Abstract: A facile synthesis of novel trifluoromethyl-containing pyrano-, pyrazolo- and isoxazolo-fused tropone compounds 4a,b , 5a,b , and 6a,b , respectively, by cyclizations of ( E )-3-[3-(trifluoromethylphenyl)acryloyl]tropolones 3a,b is described. The substrates 3a,b were prepared by Claisen-Schmidt condensation reaction of 3-acetyltropolone ( 1 ) with 3- or 4-(trifluoromethyl)benzaldehydes 2a,b .