SiO2 Nanoparticle‐catalyzed Facile and Efficient One‐pot Synthesis of N‐alkyl‐2,5‐bis[(E)‐2‐phenylvinyl]‐1,3‐dioxol‐4‐amine Under Solvent‐free Conditions

1,3‐Dioxole‐4‐amine derivatives have been prepared efficiently in one‐pot reaction using nanosized SiO₂ as a heterogeneous catalyst. The present method does not involve any hazardous organic solvents or catalysts. The high surface‐to‐volume ratio of SiO₂ nanoparticle has promising features for the reaction response such as the short reaction time, good to excellent yields, easy of operation and work‐up procedure, and purification of products by non‐chromatographic methods.     

Reactions of 5‐methylene‐1,3‐thiazolidine‐2‐thione and 5‐methylene‐2‐oxazolidinone with isocyanates catalyzed by bases

5‐Methylene‐1,3‐thiazolidine‐2‐thione and 5‐methylene‐2‐oxazolidinone can react with isocyanates to give the corresponding condensed urethanes in high yields in the presence of organic or inorganic bases under mild reaction conditions. © 2001 John Wiley & Sons, Inc. Heteroatom Chem 12:610–616, 2001     

`Inverse‐Electron‐Demand' Diels‐Alder Reactions of (E)‐3‐Diazenylbut‐2‐enes in Water

The cycloadditions of (E)‐3‐diazenylbut‐2‐enes 1 with a variety of alkenes 2 – 6 were carried out in water as well as in organic solvents. The reactions were always faster in heterogeneous aqueous medium than in the organic solvents. These conjugated diazenyl‐alkenes behave mainly as heterodienes, and the Diels‐Alder adducts are the sole or at least main reaction products. Pyrroles derived from zwitterionic [3+2] cycloaddition reactions were observed in some cases. The cycloaddition of 1a with (+)‐2‐(ethenyloxy)‐3,7,7‐trimethylbicyclo[4.1.0]heptane ( 5 ) is the first example of an asymmetric `inverse electron‐demand' Diels‐Alder reaction carried out in pure water.     

Efficient Domino Approach to Polysubstituted 2‐Hydroxyindole‐3,4‐(2H,5H)‐diones

Concise and efficient domino [3 + 2] heterocyclization promoted by HCOOH has been established for unprecedented synthesis of 15 examples of 2‐hydroxyindole‐3,4‐(2H,5H)‐diones in good yields. The present methodology shows attractive properties such as mild reaction conditions, concise one‐pot operation, short reaction periods of 15–20 min, and easy purification. The resulting 2‐hydroxyindole‐3,4(2H,5H)‐diones are of importance for organic and medicinal research.     

Theoretical insights into the excited‐state process of 4‐tert‐butyl‐2‐(5‐(5‐tert‐butyl‐2‐methoxyphenyl)thiazolo[5,4‐d]thiazol‐2‐yl)‐phenol

In this paper, we theoretically explore the motivation and behaviors of the excited‐state intramolecular proton transfer (ESIPT) reaction for a novel white organic light‐emitting diode (WOLED) material 4‐tert‐butyl‐2‐(5‐(5‐tert‐butyl‐2‐methoxyphenyl)thiazolo[5,4‐d]thiazol‐2‐yl)‐phenol (t‐MTTH). The “atoms in molecules” (AIM) method is adopted to verify the formation and existence of the hydrogen bond O? H···N. By analyzing the excited‐state hydrogen bonding behaviors via changes in the chemical bonding and infrared (IR) vibrational spectra, we confirm that the intramolecular hydrogen bond O? H···N should be getting strengthened in the first excited state in four kinds of solvents, thus revealing the tendency of ESIPT reaction. Further, the role of charge‐transfer interaction is addressed under the frontier molecular orbitals (MOs), which depicts the nature of the electronic excited state and supports the ESIPT reaction. Also, the electron distribution confirms the ESIPT tendency once again. The scanned and optimized potential energy curves according to variational O? H coordinate in the solvents demonstrate that the proton transfer reaction should occur in the S₁ state, and the potential energy barriers along with ESIPT direction support this reaction. Based on the excited‐state behaviors reported in this work, the experimental spectral phenomenon has been reasonably explained.     

A Novel and Efficient Synthesis of 3‐[(4,5‐Dihydro‐1H‐pyrrol‐3‐yl)carbonyl]‐2H‐chromen‐2‐ones (=3‐[(4,5‐Dihydro‐1H‐pyrrol‐3‐yl)carbonyl]‐2H‐1‐benzopyran‐2‐ones)

An efficient one‐pot synthesis of 3‐[(4,5‐dihydro‐1H‐pyrrol‐3‐yl)carbonyl]‐2H‐chromen‐2‐one (=3‐[(4,5‐dihydro‐1H‐pyrrol‐3yl)carbonyl]‐2H‐1‐benzopyran‐2‐one) derivatives 4 by a four‐component reaction of a salicylaldehyde 1 , 4‐hydroxy‐6‐methyl‐2H‐pyran‐2‐one, a benzylamine 2 , and a diaroylacetylene (=1,4‐diarylbut‐2‐yne‐1,4‐dione) 3 in EtOH is reported. This new protocol has the advantages of high yields (Table), and convenient operation. The structures of these coumarin (=2H‐1‐benzopyran‐2‐one) derivatives, which are important compounds in organic chemistry, were confirmed spectroscopically (IR, ¹H‐ and ¹³C‐NMR, and EI‐MS) and by elemental analyses. A plausible mechanism for this reaction is proposed (Scheme 2).     

Synthesis,structure and cytotoxicity of new 2‐[(3‐aminopropyl)dimethylsilyl]‐5‐furfural diethylacetals and 2‐[(3‐aminopropyl)dimethylsilyl]‐5‐phenylfurans

Novel 2‐[(3‐aminopropyl)dimethylsilyl]‐5‐furfural diethylacetals and 2‐[(3‐aminopropyl)di‐methylsilyl]‐5‐phenylfurans have been synthesized by a hydrosilylation reaction of aliphatic and heterocyclic N‐allylamines in the presence of the Speier's catalyst. The effects of the structure of the amine and nature of organic substituent at the furan ring on the cytotoxicity of the new compounds have been studied. Copyright © 2013 John Wiley & Sons, Ltd.     

Synthesis and Cytotoxic Evaluation of Novel 1,2,3‐Triazole‐4‐Linked (2E,6E)‐2‐Benzylidene‐6‐(4‐nitrobenzylidene)cyclohexanones

This work describes the synthesis of novel 1,2,3‐triazole‐4‐linked (2E,6E)‐2‐benzylidene‐6‐(4‐nitrobenzylidene)cyclo‐hexanones starting from cyclohexanone. 1‐(Cyclohex‐1‐en‐1‐yl)piperidine, the enamine from cyclohexanone and piperidine, reacted with 4‐nitrobenzaldehyde to obtain 2‐(4‐nitrobenzylidene)cyclohexanone. Condensation of the latter compound with (prop‐2‐yn‐1‐yloxy)benzaldehyde derivatives under acidic conditions gave (4‐nitrobenzylidene)‐[(prop‐2‐yn‐1‐yloxy)‐benzylidene]cyclohexanones. Finally, ‘click reaction’ of these derivatives and various organic azides led to the title compounds. All compounds were examined by MTT assay for cytotoxic activity in one human breast cancer cell line, MDA‐MB‐231.     

Synthesis of Functionalized Novel α‐Amino‐β‐alkoxyphosphonates through Regioselective Ring Opening of Aziridine‐2‐phosphonates

Aziridines are highly useful compounds as building blocks for the synthesis of important organic compounds. Amino acid synthesis by aziridine ring opening reaction is a good example to the use of aziridines. Although this reaction is studied by many groups, the synthesis of amino phosphonic acids is less explored. In this study, we have carried out the ring opening reaction of aziridinyl phosphonates with a variety of alcohols including the more functional propargylic and allylic alcohols. These reactions provided functionalized α‐amino‐β‐alkoxyphosphonates in 40–91 % yield.     

Solvent effect on the alkaline hydrolysis of 2‐thiophenyl‐ 3,5‐dinitropyridine

The kinetics of the alkaline hydrolysis of 2‐thiophenyl‐3,5‐dinitropyridine were studied spectrophotometrically in different aquo‐organic solvents such as methanol, ethanol, n‐propyl alcohol, iso‐propyl alcohol, t‐butyl alcohol, acetonitrile, dimethyl sulfoxide, dioxane, and acetone at 30°C with various solvent compositions up to 80% (v/v) of organic components. An increase in the organic solvent percentage (v/v) has different effects on the reaction rate constants presumably due to hydrogen bond donor HBD and acceptor HBA of the medium and other solvatochromic parameters. Linear and nonlinear plots of log k against the reciprocal of the dielectric constant of the solvent were obtained. The effects are too complex to be analyzed in terms of a single parameter, but an approach using the Kamlet–Taft solvatochromic parameters is applied successfully to six mixed aquo‐organic solvent systems. © 2006 Wiley Periodicals, Inc. Int J Chem Kinet 38: 159–165, 2006     

Pd(0)‐Catalyzed Cu(I)‐Thiophene‐2‐carboxylate‐mediated Cross‐Coupling of Heteroaromatic Thioethers and Boronic Acids—First Liebeskind–Srogl Reaction in Water

The first example of a Liebeskind–Srogl cross‐coupling reaction in water as sole reaction solvent is reported. 2‐(Methylthio)pyridine and 2‐(methylthio)benzothiazole were reacted in the presence of a Pd(0) catalyst and copper(I) thiophene‐2‐carboxylate with a series of arylboronic acids. These cross coupling reactions in water proceeded well with electron‐rich boronic acids and gave comparable yields to literature examples using organic solvents. Electron‐poor boronic acids gave somewhat lower yields in aqueous medium.     

Copper‐catalyzed Synthesis of N‐alkylated 2‐(4‐substituted‐1H‐1,2,3‐triazol‐1‐yl)‐1H‐indole‐3‐carbaldehyde by Step‐wise and One‐pot Three‐component Huisgen's 1,3‐dipolar Cycloaddition Reaction

An efficient method for the synthesis of N‐alkylated 2‐(4‐substituted‐1H‐1,2,3‐triazol‐1‐yl)‐1H‐indole‐3‐carbaldehyde has been developed starting from oxindole and indole using Huisgen's 1,3‐dipolar cycloaddition reaction of organic azides to alkynes. The effect of catalysts and solvent on these reactions has been investigated. Among all these conditions, while using CuSO₄·5H₂O, DMF was found to be the best system for this reaction. It could also be prepared in a one‐pot three‐component manner by treating equimolar quantities of halides, azides, and alkynes. The Huisgen's 1,3‐dipolar cycloaddition reaction was performed using CuSO₄·5H₂O in DMF with easy work‐up procedure.     

High‐quality poly[2‐methoxy‐5‐(2′‐ethylhexyloxy)‐p‐phenylenevinylene] synthesized by a solid–liquid two‐phase reaction: Characterizations and electroluminescence properties

Poly[2‐methoxy‐5‐(2′‐ethylhexyloxy)‐p‐phenylenevinylene] (MEH‐PPV) with a molar mass of 26–47 × 10⁴ g mol^?1 and a polydispersity of 2.5–3.2 was synthesized by a liquid–solid two‐phase reaction. The liquid phase was tetrahydrofuran (THF) containing 1,4‐bis(chloromethyl)‐2‐methoxy‐5‐(2′‐ethylhexyloxy)benzene as the monomer and a certain amount of tetrabutylammonium bromide as a phase‐transfer catalyst. The solid phase consisted of potassium hydroxide particles with diameters smaller than 0.5 mm. The reaction was carried out at a low temperature of 0 °C and under nitrogen protection. No gelation was observed during the polymerization process, and the polymer was soluble in the usual organic solvents, such as chloroform, toluene, THF, and xylene. A polymer light‐emitting diode was fabricated with MEH‐PPV as an active luminescent layer. The device had an indium tin oxide/poly(3,4‐ethylenedioxylthiophene) (PEDOT)/MEH‐PPV/Ba/Al configuration. It showed a turn‐on voltage of 3.3 V, a luminescence intensity at 6.1 V of 550 cd/m², a luminescence efficiency of 0.43 cd/A, and a quantum efficiency of 0.57%. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 3049–3054, 2004     

Preparation of 2‐phenyl‐2‐hydroxymethyl‐4‐oxo‐1,2,3,4‐tetrahydroquinazoline and 2‐methyl‐4‐oxo‐3,4‐dihydroquinazoline derivatives formation

The cyclization of phenacyl anthranilate has been studied with the aim to develop the synthesis of 2‐(2′‐aminophenyl)‐4‐phenyloxazole. However, a different course of the reaction than expected was observed. 2‐Phenyl‐2‐hydroxymethyl‐4‐oxo‐1,2,3,4‐tetrahydroquinazoline ( 3a ) was formed by the reaction of phenacyl anthranilate ( 2 ) with ammonium acetate under various conditions. 3‐Hydroxy‐2‐phenyl‐4(1H)‐quinolinone ( 4 ) arose by heating compound 3a in acetic acid. The same compound was obtained by melting compound 3a , but the yield was lower. Different types of products resulted in the reaction of compound 3a with acetic anhydride. Under mild conditions acetylated products 2‐acetoxymethyl‐2‐phenyl‐4‐oxo‐1,2,3,4‐tetrahydroquinazoline ( 7a ) and 2‐acetoxymethyl‐3‐acetyl‐2‐phenyl‐4‐oxo‐1,2,3,4‐tetrahydroquinazoline ( 8 ) were prepared. If the reaction was carried out under reflux of the reaction mixture, molecular rearrangement took place to give cis and trans 2‐methyl‐4‐oxo‐3‐(1‐phenyl‐2‐acetoxy)vinyl‐3,4‐dihydroquinazolines ( 9a and 9b ). All prepared compounds have been characterised by their ¹H, ¹³C and ¹⁵N NMR spectra, IR spectra and MS.     

An Efficient Synthesis of 3‐(3‐benzyl‐2‐(phenylimino)‐2,3‐dihydrothiazol‐4‐yl)‐6‐methyl‐4‐(2‐oxo‐2‐phenylethoxy)‐3,4‐dihydro‐2H‐pyran‐2‐one Derivatives via Multi‐Component Approach

An easy, highly efficient and a new convenient one‐pot, two‐step approach to the synthesis of 3‐(3‐benzyl‐2‐(phenylimino)‐2,3‐dihydrothiazol‐4‐yl)‐6‐methyl‐4‐(2‐oxo‐2‐phenylethoxy)‐3,4‐dihydro‐2H‐pyran‐2‐one is described. These compounds were synthesized from 3‐(3‐benzyl‐2‐(phenylimino)‐2,3‐dihydrothiazol‐4‐yl)‐4‐hydroxy‐6‐methyl‐3,4‐dihydro‐2H‐pyran‐2‐one and α‐bromoketones in good yields. The compounds 4 were synthesized by a multi‐component reaction between 1 , 2 , and 3 and the prominent features of this protocol are mild reaction conditions, operation simplicity, and good to high yields of products.     

Metal Salts of 3,3′‐Diamino‐4,4′‐dinitramino‐5,5′‐bi‐1,2,4‐triazole in Pyrotechnic Compositions

The synthesis of alkali and alkaline earth salts of 3,3′‐diamino‐4,4′‐dinitramino‐5,5′‐bi‐1,2,4‐triazole (H₂ANAT) is reported. The fast and convenient three steps reaction toward the target compounds does not require any organic solvents. In addition to an intensive characterization of all synthesized metal salts, the focus was on developing chlorine and nitrate‐free red‐light‐generating pyrotechnical formulations. Strontium 3,3′‐diamino‐4,4′‐dinitramino‐5,5′‐bitriazolate hexahydrate served as colorant and oxidizer in one molecule. The energetic properties of all developed pyrotechnical formulations assure safe handling and manufacturing.     

One‐Pot,Three‐Component Synthesis of 1‐(2‐Hydroxyethyl)‐1H‐1,2,3‐triazole Derivatives by Copper‐Catalyzed 1,3‐Dipolar Cycloaddition of 2‐Azido Alcohols and Terminal Alkynes under Mild Conditions in Water

A safe, efficient, and improved procedure for the regioselective synthesis of 1‐(2‐hydroxyethyl)‐1H‐1,2,3‐triazole derivatives under ambient conditions is described. Terminal alkynes reacted with oxiranes and NaN₃ in the presence of a copper(I) catalyst, which is prepared by in situ reduction of the copper(II) complex 4 with ascorbic acid, in H₂O. The regioselective reactions exclusively gave the corresponding 1,4‐disubstituted 1H‐1,2,3‐triazoles in good to excellent yields. This procedure avoids the handling of organic azides as they are generated in situ, making this already powerful click process even more user‐friendly and safe. The remarkable features of this protocol are high yields, very short reaction times, a cleaner reaction profile in an environmentally benign solvent (H₂O), its straightforwardness, and the use of nontoxic catalysts. Furthermore, the catalyst could be recovered and recycled by simple filtration of the reaction mixture and reused for ten consecutive trials without significant loss of catalytic activity. No metal‐complex leaching was observed after the consecutive catalytic reactions.     

Copper(I)‐N2S2‐salen type complex covalently anchored onto MCM‐41 silica: an efficient and reusable catalyst for the A3‐coupling reaction toward propargylamines

The immobilization of copper complexes by covalent anchoring of the ligand on the surface of mesoporous MCM‐41 has been described. Bis[2‐(phenylthio)benzylidene]‐1,2‐ethylenediamine as a new N₂S₂ donor salen‐type ligand was covalently anchored onto nanopores of MCM‐41 coordinated with copper (I) halide. The organic–inorganic hybrid material was achieved readily using 3‐mercaptopropyltrimethoxysilane as a reactive surface modifier. 2‐Nitrobenzaldehyde was reacted smoothly with the thiol moieties in order to form functionalized nanoporous silica with carbaldehyde groups. The resulting supported organic moieties were converted to thiosalen ligand and coordinated with CuX (X = CN, Cl, Br, I). Characterization of the heterogeneous catalyst by X‐ray diffraction, N₂ sorption, FT‐IR, diffuse reflectance UV‐visible and TGA techniques indicated successful grafting of the copper complex inside the nano‐channels of MCM‐41. The heterogenized catalyst was evaluated by the Mannich condensation reaction of aldehydes, amines and alkynes. In this reaction, the corresponding propargylamines were obtained as single products in good to excellent yields. Factors such as reaction temperature, solvent, catalyst loading, leaching and reusability of the catalyst also were discussed. The use of MCM‐41 as support permits an easier separation and recycles with only a marginal decrease in reactivity. Copyright © 2013 John Wiley & Sons, Ltd.     

Green synthesis of new pyrimido[4,5‐d]pyrimidine derivatives using 7‐aminonaphthalene‐1,3‐disulfonic acid‐functionalized magnetic Fe3O4@SiO2 nanoparticles as catalyst

We, herein, describe a novel, simple, efficient and one‐pot multi‐component procedure for the synthesis of substituted pyrimido[4,5‐d]pyrimidines via reaction of N,N‐dimethyl‐6‐amino uracil, isothiocyanate and aromatic aldehydes promoted by 7‐aminonaphthalene‐1,3‐disulfonic acid (ANDSA)‐functionalized magnetic Fe₃O₄@SiO₂ in water as solvent and without using any other harmful organic reagents. Compared with other reactions, using these organic–inorganic hybrid heterogeneous catalysts can help us to achieve a green procedure, high catalytic activity, easy recovery with an external magnetic field, and short reaction times.     

The Synthesis of New Heterocycles Using 2‐(4‐Chloro‐1,3‐dihydro‐3,3,7‐trimethyl‐2H‐indol‐2‐ylidene) Propanedial

4‐Chloro‐2,3,3,7‐tetramethyl‐3H‐indole (an indolenine) was produced by the reaction of 5‐chloro‐2‐methylphenylhydrazine hydrochloride with 3‐methylbutan‐2‐one via Fischer reaction. Exposure of the indolenine to the Vilsmeier reagent at 50°C produced a β‐diformyl compound, 2‐(4‐chloro‐1,3‐dihydro‐3,3,7‐trimethyl‐2H‐indol‐2‐ylidene)propanedial. This dialdehyde was reacted with arylhydrazines, acetamidinium chloride, urea, thiourea, guanidinium chloride, and cyanoacetamide to give various 5‐membered and 6‐membered heterocyclic products, each carrying a 4‐chloro‐3,3,7‐trimethyl‐3H‐indol‐2‐yl unit as a substituent, in excellent yields.