Current Organic Chemistry - Volume 16, Issue 7, 2012

This article reviews the complexation properties of various bis-porphyrins, linked by either flexible or rigid spacers. The fascinating supramolecular architectures obtained by complexation of bis-porphyrins feature specific structural, physico-chemical, supramolecular and photophysical properties, with an array of potential applications in material chemistry.

Pyridazin-3(2H)-ones are inexpensive, stable, and easily prepared heterocycles. Since pyridazin-3(2H)-ones readily form stable anions, and can act as good leaving group. Their utility as synthetic auxiliaries was recently demonstrated by Yoon’s group. 2- Substituted-pyridazin-3(2H)-ones are also useful both the electrophilic agents and equivalents for the functionalization of the electron rich compounds and active methylenes, and synthones. 2-Substituted-pyridazin-3(2H)-ones are novel green agents because that can be recovered quantitatively and recycled. In this review, the preparation and the synthetic application of 2-substituted-pyridazin-3(2H)-ones are described.

C-glycosylflavonoids represent a group of oxygen heterocyclic compounds found widespread in a variety of plants. Synthetic organic chemists are now progressively utilizing C-glycosylflavonoid scaffolds due to their high biological potential. The present review deals with advances in C-glycosylflavonoids research, namely establishing a new updated database of the natural occurrence of Cglycosylflavonoids - one hundred and nine new structures have been reported up to 2011. The structural characterization of some novel C-glycosylflavonoids from various plant species is also discussed. The reported organic synthetic routes along with the biosynthetic aspects of C-glycosylflavonoids are also reviewed. Finally the paper underlines the wide range of C-glycosylflavonoid biological activity. The mentioned topics are detailed in particular chapters and are supported in 187 references.

In view of the unique properties, like high solubility in most of the organic solvents, poor complexing ability, low charge density, stability under mild conditions and high electronegativity, transition metal perchlorates have been found to be highly effective catalysts/ reagents in wide variety of functional group transformations leading to the synthesis of large number of important organic compounds. This review presents the recent applications of important transition metal perchlorates as safe catalysts/reagents for organic functional group transformations.

This review summarizes research results concerning the reactions of phosphonyl carbanions with different carbon-nitrogen systems, amines, amides, imines, oximes, hydrazones, nitriles, diazo compounds, isocyanates, and azides, reported by us and other research group over the last years. It outlines the utility of such reactions in various aspects of heterocyclic chemistry. Some of these reactions have been applied successfully to the synthesis of biologically important compounds. A brief account on the synthesis of Horner reagents was also displayed.

The present report is concerned with the designing, obtaining and characterization of novel light –sensitive molecules, belonging to second generation meso-tetraarylporphyrin derivatives. A new structure of A3B porphyrin, namely: 5-(4-pyridyl)-10,15,20-tris(4- phenoxyphenyl)-porphyrin was synthesized in fair yield by multicomponent reaction and characterized by 1H-NMR, FT-IR, UV-vis, fluorescence, MS, HPLC, TLC, AFM and XRD techniques. Tailoring porphyrins by introducing a pyridyl substituent in one of the meso-aryl groups confers some degree of hydrophilicity and may cause absorption and fluorescence emission bands in the long wavelength region. Besides, as it was expected, because of the relatively rigid planar structure, due to substitution with three phenoxy substituents, this porphyrin is characterized by a value of 0.219 for fluorescence quantum yield, a higher value in comparison with usual porphyrins. In solution, by UV-vis and fluorescence spectra, the effects of pH and concentration upon H and J aggregates of the porphyrin are discussed. Xray diffraction and atomic force microscopy investigations proved that this newly synthesized porphyrin is able to generate stable selfassembly in preferred orientations, such as multilayer of lamellar triangles, densely packed and homogeneous, with dimensions around 440 nm, finally forming pyramidal type structures. CHCl3 favors the spiral organization of the pyramids so that rings and even tubes of various diameters ranging from 1μm to 4.5 μm were formed.

RuCl3·3H2O was found to be an effective catalyst for one-pot reactions of benzylic alcoholes with indoles affording the corresponding bis(indolyl)methanes under air atmosphere at room temperature in moderate to excellent yields. It is noteworthy that the RuCl3·3H2O system displayed a preference for the primary versus secondary benzylic group of a benzylic diol in intramolecular competition experiments.