Volume 23, Issue 1

Novel rel -(5a R ,6 R ,11b S )-6-hydroxy-3,5a,6,11b-tetrahydro-2 H ,5 H -chromeno[4′,3′:4,5]thiopyrano[2,3- d ][1,3]thiazole-2-ones were synthesized via tandem hetero-Diels-Alder-hemiacetal reaction of 5-(2 - hydroxybenzylidene)-4-thioxo-2-thiazolidinones and α,β-unsaturated aldehydes. The stereochemistry of cycloadditions was confirmed by NMR spectra and a single crystal X-ray diffraction analysis.

Synthesis and characterization of 5,5′-bi(1,10-phenanthroline) ( 3 ) are described. Compound 3 was obtained by treatment of 5-chloro-1,10-phenanthroline ( 1 ) with 4-hydroxy- phthalonitrile ( 2 ) in the presence of K 2 CO 3 as a base in DMF at room temperature for 25 h.

Synthesis, characterization and biological activity of novel 4,5-diaryl/heteroaryl thiophene-2-carboxylic acid derivatives are described. Aryl/heteroaryl esters were converted to substituted thiophene esters via a Vilsmeier-Haack reaction, which were then hydrolyzed to 4,5-diaryl/heteroaryl thiophene-2-carboxylic acid derivatives 8a–h . All products were characterized by 1 H NMR, 13 C NMR, IR and MS. Antibacterial activity of the synthesized compounds against two Gram-positive and two Gram-negative bacteria, as well as their anticancer activity against PC-3 cell line (human prostate cancer cell lines) were evaluated.

Two novel dicarbazolyltriphenylethylene-substituted fluorene derivatives DctF and Dct 2 F were synthesized by the Wittig-Horner and Suzuki coupling reactions. It was reasoned that introducing linear alkyl chains into the fluorene structure could facilitate the deposition of high-quality films by an economical and simple process. The thin solid films of DctF and Dct 2 F show strongly enhanced emissions in comparison to their dilute solutions, which indicate the aggregation-induced emission enhancement (AIEE). Their decomposition temperatures ( T d ) exceed 400°C and the glass transition temperature ( T g ) of DctF is 105°C. The maximum fluorescence emission wavelengths are in the region of 458–469 nm.

A series of novel tricyclic benzoxazepines with fused imidazolone ring was prepared in five steps starting from the corresponding benzoxazolones 1–3 . The key to the reported synthetic approach is transformation of 3-(2-oxopropyl)-2(3 H )-benzoxazolones 4–6 to 1-(2-hydroxyphenyl)-4-methyl-1,3-dihydro-2 H -imidazol-2-ones 7–12 , and their subsequent conversion to the phenoxyacetic acids 19–24 , which were finally acylated in polyphosphoric acid to form the oxazepine ring.

Under the catalysis of 1 mol% of Br 2 or HBr at room temperature, indoles undergo a rapid reaction with 3-hydroxy-3-(indol-3-yl)indolin-2-ones to give asymmetric 3,3-di(indol-3-yl)indolin-2-ones with high efficiency and wide substrate scope. This is a rare example of Br 2 acting as a Lewis acid catalyst. Theoretical calculations suggest that both the catalytic activity of the catalysts and the stability of reaction intermediates are responsible for the high efficiency of this reaction.

A series of dipicolinic acid derivatives was synthesized and investigated for antimicrobial and antioxidant activity. Mono and bis derivatives of ethyl dipicolinate were utilized as starting materials for synthesis of mono- and bis-hydrazides. Thiosemicarbazides were obtained by reaction of hydrazides with isothiocyanates and cyclized into triazoles, thiadiazoles, oxadiazoles and thiazolidinones. Some of these products, especially those incorporating a thiazolidinone moiety in their structure, are excellent antioxidants, DPPH scavengers and antifungal agents.

The hydrazide 5 , that was obtained from 1-(4-fluorophenyl)piperazine ( 1 ), was converted to the corresponding carbothioamides 6a–c by the reaction with alkyl(aryl) isothiocyanates. The synthesis of conazole analogs 10a–f was performed via the intermediary of triazoles 7a–c . The condensation of triazoles 7a–c with several heterocyclic amines in the presence of formaldehyde afforded the corresponding N -aminoalkylated triazoles 11–14 . The effect of different catalysts and solvents on conventional and microwave (MW)-prompted reactions was examined. The synthesized compounds were screened for their antimicrobial activities.

With an intention to synergize the antimicrobial activity of 1,3-diphenyl pyrazole and chromene derivatives, 20 hybrid compounds were synthesized and evaluated for their antimicrobial activity. Structures of the newly synthesized compounds were established by elemental analysis and spectral data. All compounds were evaluated for their antimicrobial activity against Gram positive and Gram negative bacteria and antifungal activity by a well diffusion method. Compounds 8 , 10 , 16 and 21 show reasonable antibacterial and antifungal activity.

Condensation reaction of dimedone with 2-amino-1-methyl-4,5-diphenyl-1 H -pyrrole-3-carbonitrile in ethanol containing a catalytic amount of p -toluenesulfonic acid (TsOH) afforded 2-(5,5-dimethyl-3-oxocyclohex-1-enylamino)-1-methyl-4,5-diphenyl-1 H -pyrrole-3-carbonitrile. This compound was then treated with olefins, formed by Knoevenagel condensation of aryl aldehydes and malononitrile, in ethanol in the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) as catalyst to give novel cyclic compounds in high yields. A new hexacyclic heterocyclic compound was formed when 2-hydroxybenzaldehyde was used as the aldehyde. The reactions were done using ultrasonic irradiation. The synthesized compounds were characterized by IR, 1 H NMR, and 13 C NMR spectra, elemental analysis and evaluated for their antibacterial activity against Gram-positive bacteria ( Staphylococcus aureus and Micrococcus luteus ) and Gram-negative bacterium ( Escherichia coli ).