Volume 72, Issue 5

The first example of 1,3-dipolar cycloaddition reactions of C -aryl (or hetaryl)- N -phenylnitrones to monosubstituted ylidene malononitriles and 4-benzylidene-2-phenyl-oxazol-5(4 H )-one is described. The reaction of C -(4-(dimethylamino)phenyl)- N -phenyl-nitrone (1a) with 2-(4-substituted-benzylidene)malononitriles 2a , b in dry toluene, in the absence of catalyst, at reflux temperature furnished the novel cycloadducts 2-(3-aryl-2-phenyl-2,3-dihydro-1,2,4-oxadiazol-5-yl)-3-(4-methoxyphenyl)acrylonitriles 3a , b . Refluxing C -aryl (or hetaryl)- N -phenylnitrones 1b–i with 2-(4-methoxy-benzylidene)malononitrile ( 2a ) in dry toluene, in the absence of catalyst, gave the unexpected 2-cyano-3-(4-methoxyphenyl)-acrylamide ( 5 ), as the sole product. On the other hand, refluxing 4-benzylidene-2-phenyloxazol-5(4 H )-one ( 7 ) with an equimolar amount of C -aryl (or hetaryl)- N -phenyl-nitrones 1a–c , f–i in absolute EtOH afforded the previously unknown 5-anilino-4-benzoyl-2-phenyloxazole ( 10 ), as the only isolable product. The resulting products were formed with a high degree of regio- and stereoselectivity. Quantum chemical calculations were performed to verify stereoselectivity of the studied reaction. A mechanistic proposal is presented to rationalize the formation of these products.

Interaction of AgCl with bis(diphenylphosphino)methane (dppm) in THF/MeCN in the presence of K[PF 6 ] or [Et 4 N]Br afforded typical trinuclear cationic trigonal-bipyramidal complexes [Ag 3 ( μ 3 -Cl) 2 ( μ -dppm) 3 ][PF 6 ] ( 1 ) or [Ag 3 ( μ 3 -Br) 2 ( μ -dppm) 3 ][AgBr 2 ] ( 2 ), respectively. Treatment of AgBr with bis(diphenylphosphino)ethane (dppe) in THF/MeCN in the presence of [Et 4 N]Br gave a polymeric complex {[Et 4 N][Ag 2 ( μ -Br) 3 ( μ -dppe)]} n ( 3 ) with a dinuclear {Ag 2 ( μ -Br) 3 } core. The reaction of AgCl with dppe or bis(diphenylphosphino)propane (dppp) in THF/MeCN in the presence of [Et 4 N]Cl resulted in the isolation of a dinuclear anionic complex [Et 4 N] 2 [(AgCl 2 ) 2 ( μ -dppe)] ( 4 ) with one μ -dppe bridge or a dinuclear neutral complex [(AgCl) 2 ( μ -dppp) 2 ] ( 5 ) with two μ -dppp bridges and a 12-membered ring, respectively. The structures of complexes 1–5 with the bidentate phosphine ligands were determined by single-crystal X-ray diffraction.

In this work, the reaction of 2,2′,2″-nitrilotriethanol (NTE) with a 1:1 mixture of CdI 2 and HgI 2 is investigated. The complex [Cd(NTE) 2 ][Hg 2 ( μ -I) 2 I 4 ] was synthesized and identified by elemental analysis, FT-IR, 1 H NMR spectroscopy and single-crystal X-ray diffraction. The structure of the [HNTE]Cl salt is also presented. In the crystal structure of the complex, the cadmium atom has a CdN 2 O 6 environment in a slightly distorted cube geometry. This geometry is one of the rare cube geometries with a minimum distortion among the Cambridge Structural Database structures for cadmium complexes. The anionic moiety has a binuclear structure with the mercury atoms being in tetrahedral environments. In the network of the complex, in addition to O−H · · · I hydrogen bonds, there are I · · · I interactions which lead to ten-membered rings.

Replicas retaining the structural characteristics of softwood ( Pinus sylvestris ) were obtained by infiltrating pretreated templates with a methanolic methoxymagnesium methyl carbonate (MeOMgOCO 2 Me) solution as a precursor which then hydrolyzed into MgCO 3 nanoparticles. Subsequent calcination at temperatures ranging from 500 to 1450°C yielded annealed MgO replicas on levels of hierarchy from the macroscopic to the submicron scale. The mechanical stability of the replicas could be improved through calcination at 1450°C. However, this treatment leads to considerable shrinkage (Δ ax =56%). Even more stable MgO replicas were obtained by infiltrating the pine template first with MeOMgOCO 2 Me, followed by a second infiltration step with an ethanolic tetraethyl orthosilicate (TEOS) solution and subsequent calcination at 1350°C. The resulting replicas constitute an MgO framework overgrown with Mg 2 SiO 4 (forsterite) and exhibit compression strengths of 31±8 MPa, as well as hierarchical structures combined with an anisotropic porosity.

In the search for new bioactive compounds from extremophilic actinomycetes, a new marine actinomycete strain, Nocardiopsis lucentensis sp. ASMR2 has been isolated and taxonomically identified from marine plants collected in the Red Sea at Hurghada coasts. A large-scale fermentation of the strain on modified rice solid medium was performed, followed by work-up and purification of the obtained extract using a series of chromatographic purifications, delivering the novel butenolide system 3′-hydroxy- N -(2-oxo-2,5-dihydrofuran-4-yl)propionamide ( 1a ) along with the naturally new 4-methoxy-2 H -isoquinolin-1-one ( 2 ). Furthermore, eight known bioactive compounds are also reported, namely, indole-3-carboxylic acid, indole-3-acetic acid, indole-3-acetic acid methyl ester, furan-2,5-dimethanol, tyrosol, glycerol linoleate, cyclo-(Tyr, Pro), and adenosine. The chemical structures of the new compounds ( 1a , 2 ) were confirmed by extensive one- and two-dimensional (1D and 2D) nuclear magnetic resonance (NMR) spectroscopy, electron ionization high resolution (EI-HR) mass spectrometry, and by comparison with literature data. The antimicrobial activity of the strain extract, as well as of compounds 1a and 2 , were studied using a panel of pathogenic microorganisms. The in vitro cytotoxicity of the bacterial extract and compounds 1a and 2 were studied against the human cervix carcinoma cell line (KB-3-1) and its multidrug-resistant subclone (KB-V1).

A new, convenient, and efficient method for the synthesis of 1 H -pyrazolo[1,2- b ]phthalazine-5,10-diones is developed starting from phthalhydrazide, aromatic aldehydes, and malononitrile using 4- N , N -dimethylaminopyridin as catalyst. This modified route provides much higher yields and a simple work-up procedure of products. Also this methodology is of interest due to the use of ethanol as a solvent without use of any toxic metals as catalyst, thus minimizing the cost, the operational hazards, and environmental pollution.

A selected set of new 4 H -benzothiopyran-4-one derivatives 6a–h has been prepared by a one-pot reaction involving deprotonated methyl 3-oxo-3(2′,4′,5′-trichlorophenyl)propanoate 5 and the appropriate aryl or alkyl isothiocyanate. 2,4,5-Trichloroacetophenone 4 , required for the synthesis of 5 , is successfully prepared by Friedel–Craft’s acetylation of 1,2,4-trichlorobenzene in 82% yield. The structures of the new compounds 5 and 6a–h are based on microanalytical and spectral (NMR, MS(EI), and HRMS) data.

The reactivity of cyclobutane moiety in 1,3-dimethyl-5-methylenebarbituric acid dimer ( 5 ) towards different nucleophiles was investigated. New derivatives of 5-(substituted methyl)-1,3-dimethylbarbiturate 6–13 were prepared in good yields using various aliphatic amines, cyanide anion, and Ph 3 P, Ph 3 As, Ph 3 Sb. Chemical structures of synthesized products were characterized using NMR, MS, and elemental analysis. The reaction of thiophenoxide and thiocyanate nucleophiles with 5 did not give any new products.