Fused π‐Extended Truxenes via a Threefold Borylation as the Key Step

On the basis of a threefold borylated truxene, which is accessible in high yields by iridium‐catalyzed borylation under CH‐activation, fused π‐extended truxenes have been synthesized by a two‐step method of first Suzuki–Miyaura cross‐coupling reaction and subsequent condensation reaction. The mild condensation method tolerates the presence of a variety of functional groups, such as nitro, fluoro, or carboxyl moieties. Furthermore, by using this approach, N‐ and S‐heteroarene analogues become accessible for the first time, as well as larger structures that represent derivatives of precursors for fullerene C₆₀ or buckybowls. The attached tert‐butyl groups make all derivatives sufficiently soluble to allow full spectroscopic and electrochemical investigations. Postfunctionalization of selected derivatives for further synthetic applications of the compounds is also presented.     

Synthesis of Vinyl Sulfones by Ring Opening of 4,4‐Dioxo‐2,3‐dihydrobenzo[b][1,4]oxathiines and Their In Situ Reactions with Nucleophilic or Electrophilic Agents

A new, mild method of synthesis of 2‐hydroxyphenyl vinyl sulfones from 4,4‐dioxo‐2,3‐dihydrobenzo[b][1,4]oxathiine derivatives is described. The products were further modified in situ, either by Michael addition of nucleophiles or by reaction of the 2‐hydroxy group with an electrophile. The method can be utilized to immobilize proteins on a suitable support, or for other similar applications, as generation of the vinyl sulfone is always accompanied by formation of phenolate anion that can be used to bond in situ the vinyl sulfone to a suitable support.     

Photochemische Umwandlungen, 41 [1] 3ω → 3 π-Isomerisierungen von Monohetero-trishomobenzol-derivaten. Vorläufige mitteilung

The all-cis-oxa- and azatrishomobenzene diesters 4a and 4b resp. undergo thermally a very clean 3ω → 3π isomerization reaction yielding the heterocyclonona-2, 5, 8-triene derivatives 6a and 6b resp. (E_a = 27.4 and 26.5 kcal/mole). In contrast, the cis, cis, trans-oxatrishomobenzene diester 9 is stable up to 170°. Some applications and limitations of this 3ω → 3π-route to iso- and heterocyclononatriene derivatives are discussed.     

A new methodology for the oxidation of sulfides with Fe(III) catalysts

A variety of sulfides were converted to the corresponding sulfoxide derivatives with 70% t‐BuOOH (water) as the oxidant in the presence of catalytic quantity of Fe₂(SO₄)₃. The method described has a wide range of applications, involves simple work‐up, exhibits chemoselectivity/enantioselectivity and proceeds under mild reaction conditions. The resulting products are obtained in good yield within a reasonable time. Copyright © 2012 John Wiley & Sons, Ltd.     

Synthesis and Characterization of Some New Heteroaromatic Compounds Having Chirality Adjacent to a 1,3,4‐Thiadiazole Moiety and Their Antimicrobial Activities

Through a cyclization reaction of 2‐phenylbutyric acid with N‐ phenylthiosemicarbazide and POCl₃, novel 1,3,4‐thiadiazole derivatives were synthesized. Their structures were confirmed using IR, ¹H NMR, and ¹³C NMR spectroscopies and elemental analysis. The antibacterial activities of the obtained 1,3,4‐thiadiazole derivatives were tested against Gram‐negative bacteria (Salmonella enteritidis , Salmonella typhimurium , Enterobacter aerogenes , Salmonella infantis , Salmonella kentucky , and Escherichia coli ) and Gram‐positive bacteria (Staphylococcus aureus , Bacillus subtilis , and Enterococcus durans ) using a disk diffusion method. Moreover, an antifungal activity experiment was performed against Candida albicans using the disk diffusion method. It was observed that the synthesized 1,3,4‐thiadiazole derivatives exhibited effective antimicrobial activity against S. aureus , E. coli , and C. albicans . Based on these results, the 1,3,4‐thiadiazole derivatives can be considered as a source of bioactive agents for pharmacological and medicinal applications.     

An Efficient and Chemoselective Knoevenagel/Hemiketalization Process for the Synthesis of New 2H‐Chromenes in a One‐Pot Three‐Component Reaction

A novel L ‐proline‐catalyzed mild and ecological approach towards the synthesis of 2H‐chromene derivatives was achieved by Knoevenagel reaction followed by an intramolecular hemiketalization process. In the present protocol, chemoselectivity has been successfully achieved by using L ‐proline as catalyst. This eco‐friendly and chemoselective reaction provided an alternative synthetic method to prepare previously unknown 2H‐chromene derivatives in a one‐pot reaction.     

Nonlinear Optical Properties of Porphyrin Derivatives with Electron‐donating or Electron‐withdrawing Substituents

To investigate photoelectric properties of meso‐extended porphyrin derivatives with electron‐donating or electron‐withdrawing substituents, a series of functionalized porphyrin materials have been designed and synthesized by Suzuki coupling reaction. The meso‐extended structures were fully characterized by ¹H NMR, IR spectroscopy and mass spectrometry. The photophysical properties of porphyrin derivatives were carefully examined by UV‐Visible and fluorescence spectra, and the solvatochromic effect was observed and discussed. In particular, Z‐scan technique was employed to characterize the third‐order nonlinear optical (NLO) properties of the products such as nonlinear absorption and refraction, the third‐order nonlinear refractive indexes (??⁽³⁾‐value) of these porphyrin derivatives achieved 3.9×10^?12 esu. In addition, the compounds could be self‐assembled into highly organized morphologies through phase‐exchange method. All the results indicated that the discotic materials have the potential for optoelectronic applications.     

Oxidative Coupling via Organocopper Compounds

The type of reaction described here, which achieved preparative importance before the turn of the century in the form of the Glaser reaction, has found new applications in recent years: Syntheses of 1,3-dienes, 2,3,6,7-tetraaza-1,3,5,7-tetraenes, 2,3-diaza-1,3-dienes, hydrazine derivatives, bis(heteroallyl) compounds, hetarenes, polyhetarenes, cyclopolyarenes, protophanes, phanes, and heteraprotophanes. The reaction, which consists in the metalation of the starting substance followed by oxidative coupling of the metal derivative, merits special preparative interest when several successive coupling processes are possible (e. g. polyyne, polyarene, cyclopolyarene, and protophane syntheses). The main factors limiting its applicability are the high thermal stability of some organic copper compounds and the disproportionation of the ligands that frequently occurs as a competing reaction. Selective asymmetric linkages are not generally possible by this method.     

Synthesis and Photo Physical Properties of 9,10-Bis(hydroxyphenyl)anthracene Derivatives

Summary. Among the most promising fluorescent materials for sensor applications, anthracene and its derivatives have been widely studied. In this contribution, the synthesis and characterization of a series of isomers of bis(hydroxyphenyl)anthracene derivatives are described. The preparation of the corresponding derivatives via Suzuki cross-coupling reactions is presented with particular emphasis on finding appropriate protecting groups and studying the influence of the position of the hydroxy group on the outcome of the reaction. Moreover, the effects of protonation and deprotonation on absorption and emission spectra are reported and correlated to semi-empirical quantum mechanical calculations.     

L'ernploi du tétrafluoroborate de triéthyloxonium et ses limites,dans l'éthylation d'oxo-2 indolinc earboxanilides et thioearboxanilides

The reaction of triethyloxonium tetrafluoroborate (Meerwein's reagent) with 2-oxo indoline 3-carboxanilides ( 4 ) gives mainly the 2-ethoxyindole derivatives, together with other C- and O-ethyl compounds. In the same time, difluoro indolyloxyboranes are formed by the reaction of the anilides 4 with boron trifluoride resulting from the decomposition, in situ, of the Meerwein's reagent. These results clearly indicate some limitation for synthetic applications of this reagent.     

Selective Synthesis of Z‐Cinnamyl Ethers and Cinnamyl Alcohols through Visible Light‐Promoted Photocatalytic E to Z Isomerization

A photocatalytic E to Z isomerization of alkenes using an iridium photosensitizer under mild reaction conditions is disclosed. This method provides scalable and efficient access to Z‐cinnamyl ether and allylic alcohol derivatives in high yields with excellent stereoselectivity. Importantly, this method also provides a powerful strategy for the selective synthesis of Z‐magnolol and honokiol derivatives possessing potential biological activity.     

Synthesis and Anti‐influenza Virus Activity of Novel bis(4H‐chromene‐3‐carbonitrile) Derivatives

An efficient and convenient method for the synthesis of bis(4H‐chromene‐3‐carbonitrile) derivatives by one‐pot, multicomponent reaction of bis‐aldehydes, malononitrile, and dimedone in the presence of a catalytic amount of piperidine is reported. Bis(2‐benzylidene‐1H‐indene)‐1,3‐(2H )‐dione derivatives were obtained as the main products as a result of reaction of the bis(arylidenemalononitriles) with indandione. The anti‐influenza H5N1 virus activities of the newly prepared bis‐chromene derivatives are also investigated.     

One-pot rapid synthesis of 4H-1-benzopyran derivatives in a deep eutectic solvent

A method for introducing a biologically active heterocycle, 2-methylquinoline into the 4-position of a 2-amino-4H-1-benzopyran skeleton is described. Choline chloride/glucose (1:1 molar ratio) was used as both the solvent and catalyst in the reaction of a salicylaldehyde, methylquinoline, and cyanoacetate to obtain 2-amino-4H-1-benzopyran derivatives in 48%–80% yields after short reaction times. The effects of the deep eutectic solvent type, substrate molar ratio, cosolvent, temperature, and reaction time were examined. The method has the advantages of simple steps, environmental friendliness, mild conditions, and wide substrate applicability. This is the first attempt to synthesize methylquinoline derivatives of 4H-1-benzopyran.     

三唑嘧啶衍生物的催化制备方法

本文报道了三唑嘧啶酮类化合物的催化合成方法。烷基胺与氰基亚胺硫代二甲酯在季氨盐催化作用下得到质量好、收率高的3-烷氨基-5-氨基-1,2,4-三氮唑,进一步经过亚胺中间体并与α,β-不饱和酸酯作用后,中间产物在Lewis酸催化作用下水解得到三唑嘧啶酮。该催化方法成本低,反应条件温和,工艺安全并对环境友好。同时报道了所有中间产物的核磁共振氢谱分析结果。     

An Efficient One‐Pot Three‐Component Synthesis of Some New Polyhydroquinolines via Enaminone Intermediates

For a wide spectrum of pharmacological effects of polyhydroquinolines, this study introduces a developed safe, simple, higher yields and fast method for the synthesis of some new hexahydroquinoline derivatives using one‐pot three‐component cyclocondensation reaction, via the reaction of 1,3‐cyclohexanedione with primary amine and arylidinemalononitrile or salicylaldehyde derivatives. The prepared compounds were reacted with different reagents as N ,N‐dimethylformamide dimethylacetal, acetic anhydride, sulphuric acid, and hydrazine hydrate forming several polycyclic hexahydroquinoline and acridine derivatives. All these new compounds have been characterized by spectral data and expected to be effective pharmaceutical drugs.     

Microwave-assisted synthesis and luminescent activity of imidazo[1,2-a]pyridine derivatives

In this work, a series of phenacyl bromide derivatives was synthesized and employed as key intermediate for the synthesis of substituted imidazo[1,2-a]pyridines. First, phenacyl bromide molecules were obtained from the bromination reaction of acetophenones assisted by microwave irradiation, obtaining the products 4a-v in a 15 minutes reaction with yields in the range of 50% to 99%. Subsequently, the conjugation of these molecules with 2-aminopyridine conduced to the production of imidazo[1,2-a]pyridine derivatives ( 7a-v ) in a 60-second reaction with yields of 24% to 99%. Improved yields were determined with respect to those obtained with more tedious methodologies like thermally and mechanically assisted routes. Intense luminescence emissions in the purple and blue regions of the electromagnetic spectra were observed under UV excitation according to the nature of the substituents. This environmentally friendly methodology is expected to constitute an important class of organic compounds for the development of biomarkers, photochemical sensors, and medicinal applications.     

Synthesis of α‐Nitro‐α‐diazocarbonyl Derivatives and Their Applications in the Cyclopropanation of Alkenes and in O?H Insertion Reactions

A facile and highly efficient method for the preparation of α‐nitro‐α‐diazocarbonyl derivatives by a diazo‐transfer reaction involving (trifluoromethyl)sulfonyl azide has been developed. These substrates undergo a rhodium‐catalyzed cyclopropanation reaction with a variety of alkenes. A systematic study of the reaction indicated that the diastereoselectivity of the cyclopropanation could be effectively controlled through the modification of the steric bulk of the diazo reagent. A novel O? H insertion reaction of the metal? carbene complex derived from the α‐nitro‐α‐diazocarbonyl reagent afforded the corresponding novel α‐nitro‐α‐alkoxy carbonyl derivatives.     

Highly Regioselective Synthesis of Novel 4-O-Phosphorylated Paeonol Analogs

Abstract

4-O-phosphorylated paeonol derivatives were conveniently prepared by a facile method. Resacetophenone was prepared by the Friedel–Crafts acylation reaction of acetic acid with resorcinol. It was then phosphorylated regioselectively at the 4-O position using the Atherton–Todd reaction. An efficient, highly regioselective method to synthesize 4-O-phosphorylated paeonol derivatives is provided, and the approach has the merits of mild reaction conditions.

Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file.     

Synthesis of Novel Coumarin-7,8-cyclophosphoramide Analogs

Coumarin-7,8-cyclophosphoramide derivatives were conveniently prepared by a facile method. 7-Hydroxycoumarin was aminomethylated regioselectively at the 8-C position using the Mannich reaction. The newly formed 8-(N-alkylaminomethyl) coumarins were then coupled with bis-β-chloroethyl dichlorophosphamide to form coumarin-7,8-cyclophosphoramide analogs. An efficient, highly regioselective method to synthesize coumarin-7,8-cyclophosphoramide derivatives is provided, and the approach has the merits of mild reaction conditions.     

A Modified and Practical Synthetic Route to Indazoles and Pyrazoles Using Tungstate Sulfuric Acid

Tungstate sulfuric acid‐catalyzed Knorr reaction have been used as a simple, rapid, atom economic and green method for the synthesis of indazole and pyrazole derivatives based on the condensation of hydrazine derivatives and ß‐dicarbonyl compounds under solvent‐free conditions. It was found that the catalyst could be recovered and reused without significant loss of its activity. The use of this method provides a novel and improved modification of Knorr synthesis in terms of clean reaction profile, use of a safe catalyst and solvent‐free conditions.