Band 24, Heft 3

γ-Thiolactams were synthesized in good yields from ethyl isocyanoacetate through a sequential alkylation/isothiocyanation/radical cyclization under microwave irradiation.

Palladium (Pd) coupling reactions have become an indispensable tool in modern synthetic organic chemistry. A simple procedure to obtain isoindolinones 7 bearing a quaternary C-atom, featuring a Pd-mediated tandem process, is presented. Readily available iodoamidoacrylate 3 and boronic acids 6 are used as the starting materials.

2-(Quinolin-2-yl)quinazolin-4(3 H )-one ( Q ) was synthesized via the Brønsted acid-promoted tandem cyclization/dehydrogenation reaction with a good yield. Compound Q is a selective ‘turn-on’ fluorescent sensor for Zn 2+ ion without interference by Cd 2+ . The 1:1 binding model of Q to Zn 2+ was confirmed by the Benesi-Hildebrand analysis, Job’s plot analysis and a ultraviolet-visible (UV-Vis) titration experiment. Furthermore, the light-on fluorescent response can be observed by the naked eye under UV-lamp irradiation (365 nm).

A new aza-15-crown-5 derivative 1 bearing coumarin and hydrazone moieties was synthesized and characterized. The fluorescent sensing behavior and selectivity of 1 toward different metal ions in ethanol were investigated. There are 4-fold and 2-fold fluorescence enhancements of 1 at λ em =406 nm upon addition of five equivalents of K + and Ba 2+ , respectively. The fluorescence titration revealed the stoichiometry of 1:1 for 1 -K + 1 -Ba 2+ complexes and the binding constants (lg K s ) of 4.11 for 1 -K + and 3.61 for 1 -Ba 2+ . Compound 1 can be used as a fluorescent chemosensor for K + and Ba 2+ through discriminable photoresponse signals. The calculated detection limits for K + and Ba 2+ are 2.28 μ m and 5.21 μ m , respectively.

Three azocalix[4]arenes with distal ethyl ester residues, 5-phenylazo-25,26,27-tris[(ethoxycarbonyl)methoxy]-28-hydroxycalix[4]arene ( 2 ), 5-(o-methylphenyl)azo-25,26,27-tris[(ethoxycarbonyl)methoxy]-28-hydroxycalix[4]arene ( 3 ), 5-(p-Methylphenyl)azo-25,26,27-tris[(ethoxycarbonyl)methoxy]-28-hydroxycalix[4]arene ( 4 ), were synthesized and their binding properties with metal ions were investigated by ultraviolet (UV)/visible spectroscopy. The chromogenic behavior of these compounds upon metal ion complexation indicates a specific selectivity toward Ca 2+ ion in the presence of other cations tested. The stoichiometry of 3 to Ca 2+ ion in the complex is 1:1 and the stability constant of the complex is 1.28×10 4 m −1 .

2,3-Dihydrofuranediones were prepared by an efficient one-pot multicomponent Knoevnagel-like condensation between pyrazolecarbaldehydes or indole-3-carbaldehyde, ethyl pyruvate and bromine, followed by an intramolecular cyclization in aqueous medium.

A simple approach to assembling of functionalized spiro-butenolide-indenetriones from oxoindeno[1,2- b ]pyrrole derivatives in the presence of H 2 SO 4 is described. Simplicity of the procedure, short reaction time and excellent yields are important features of this protocol.

α -Methylene- γ -lactams were synthesized from readily available N -acylhydrazones by a tin-mediated Barbier-type reaction. The method avoids the use of toxic allylstannanes and the reaction proceeds smoothly under mild conditions.

An efficient and green one-pot method for the oxidative aromatization and bromination of pyrazolidin-3-ones under mild conditions with a HBr-H 2 O 2 system was developed. A mechanism was proposed.

New thiazole-substituted dibenzofurans 7a–j were synthesized from dibenzofuran derivatives 5a–b and substituted thiosemicarbazones 6a–h under conventional and microwave irradiation conditions. The structures of all products were established on the basis of analytical and spectral data. The synthesized compounds were evaluated for their in vitro antibacterial activity against Gram-positive and Gram-negative strains. Compounds 7b, 7d and 7h are active against Bacillus subtilis (+ve), and compound 7i displays good activity against Pseudomonas aeruginosa (-ve) strain. Compounds 7a–j were also evaluated for their in vitro antimycobacterial activity, and compound 7b shows antimycobacterial activity against Mycobacterium bovis strain.