Copper(I)-catalyzed diastereoselective formation of oxazolines and N-sulfonyl-2-imidazolines

A simple and short method for the reaction of methyl isocyanoacetate with aldehydes and N-sulfonylimines is presented. The reaction is catalyzed by copper(I) complexes and proceeds with excellent yields and high diastereoselectivities.     

Microwave-assisted synthesis of derivatives of khellinone under phase-transfer catalytic conditions

The microwave-assisted synthesis of four new 5-acetyl-4,7-dimethoxy-6-hydroxybenzofuran (khellinone) analogs is described. The structures of the obtained derivatives in the solid state are evaluated on the basis of ¹³C CP/MAS NMR spectra and theoretical calculations at DFT level. A single crystal X-ray diffraction structure is presented for 8-acetyl-7-hydroxy-4-methylcoumarin. 1,4-Bis(5-acetyl-4,7-dimethoxybenzofuran-6-yloxy)butane was evaluated for potential anticancer activity in an in vitro screening panel of 60 human tumor cell lines. Selected leukemia, non-small cell lung cancer, CNS, melanoma, ovarian, and breast cancer cell lines were sensitive to this compound. Correspondence: Elżbieta Hejchman, Department of Organic Chemistry, Faculty of Pharmacy, Medical University of Warsaw, Banacha 1, 02-097 Warsaw, Poland.     

Organocatalysed three-component domino synthesis of 1,4-dihydropyridines under solvent free conditions

An organocatalysed protocol for one-pot synthesis of 1,4-dihydropyridines via three-component coupling of cinnamaldehyde, aniline and β-keto esters under solvent free conditions at ambient temperature is reported. The reaction is generally very fast and the products are obtained in high yield. The catalytic activity of small organic molecules like amino acids (acidic, basic and neutral), ephedrine and cinchona alkaloids was studied.     

Microwaves-assisted solvent-free synthesis of N-acetamides by amidation or aminolysis

The preparation of acetamides directly from amines and an acetyl donor under microwaves without any catalyst is described. The inexpensive, solvent free, and fast reaction conditions are the important features of this procedure.     

One‐pot Synthesis of 3,4‐Dihydropyrimidin‐2(1H)‐ones Catalysed by Cupric Acetate under Solvent‐free Conditions

A solvent‐free synthesis of 3,4‐dihydropyrimidin‐2(1H)‐ones from aromatic aldehydes, β‐keto ester/acetyl acetone and urea catalysed by cupric acetate under thermal condition is reported as a simple and an efficient protocol. Compared with classical Biginelli reaction reported in 1893, this new method provides much improved modification in terms of yield and reaction time. The usage of milder catalyst, environmental friendly procedures and excellent yields within a very short time (5–15 min) are the advantages of the method in which the involvement of solvent‐free condition adds an edge to the method. Thus, the efficiency of the protocol enabled the rapid synthesis of 3,4‐dihydropyrimidin‐2(1H)‐one derivatives in a short duration.     

Microwave-assisted chemoselective copper-catalyzed amination of o-chloro and o-bromobenzoic acids using aromatic amines under solvent free conditions

Copper-catalyzed synthesis of N-aryl anthranilic acid derivatives using effective amination of 2-chloro and 2-bromobenzoic acid under microwave irradiation is reported.Some of the advantages of this method are high chemoselectivity,short reaction times,ease of work up procedure and elimination of the need for acid protection.     

Yb(OTf)3-catalyzed synthesis of pyrroles under solvent-tree conditions

Ayb(Otf)3-catalyzed approach for the synthesis of pyrroles under solvent-free conditions was achieved,which could afford the desired products with yields ranged from moderate to excellent.     

Efficient Cu(OTf)2-catalyzed and microwave-assisted rapid synthesis of 3,4-fused chromenopyridinones under neat conditions

An efficient, solvent-free, environmentally benign, Cu(OTf)₂-catalyzed and microwave-assisted fast synthesis of a fascinating class of a number of angularly fused chromenopyridinones having a carboxylate group at C-2 position on the pyridine ring via a one-pot [3+3] annulation reaction of several aminocoumarins/cyclic β-enaminones with different kinds of γ-aryl/styryl/heteroaryl-substituted-β,γ-unsaturated α-ketoesters as Michael acceptors under open atmosphere. This eco-friendly method delivers good to excellent yields of pyridine-fused-heterocycles within (15–40 min) without using any traditional oxidants and allows several important functionalities. Furthermore, by this method, stereoselective synthesis of trans-7,8-diaryl-8.9-dihydrochromeno[4,3-b]cyclopenta[e]pyridine-6,10-diones were obtained in an excellent diastereoselective manner (dr ≤ 99:1).     

Synthesis of 1,8-dioxo-decahydroacridine derivatives using sulfonic acid functionalized silica (SiO2-Pr-SO3H) under solvent free conditions

Sulfonic acid functionlized silica (SiO₂-Pr-SO₃H) was found to be an efficient and recyclable solid acid catalyst in the synthesis of 1,8-dioxo-decahydroacridine derivatives under solvent free conditions. Short reaction time, excellent yields and simple work-up are the advantages of this procedure.     

Sodium bromide catalysed one-pot synthesis of tetrahydrobenzo[b]pyrans via a three-component cyclocondensation under microwave irradiation and solvent free conditions

Sodium bromide catalysed three-component cyclocondensation of aryl aldehydes, alkyl nitriles and dimedone proceeds under microwave irradiation in solvent free conditions to give highly functionalised tetrahydrobenzo[b]pyrans in excellent yields.     

Modular CeCl3·7H2O-catalyzed multi-component synthesis of 1,2,3,4-tetrasubstituted pyrroles under microwave irradiation and their further trichloroisocyanuric acid-mediated conversion into 5-sulfenylpyrrole derivatives

A modular, multicomponent synthesis of 1,2,3,4-tetrasubstituted pyrroles promoted by the inexpensive CeCl₃·7H₂O, is reported. The reaction was carried out under microwave irradiation, affording good yields of products in short time. Scope and limitations were explored and a plausible reaction mechanism is discussed. The resulting heterocycles were smoothly and efficiently converted into their corresponding 5-arylsulfenyl derivatives by reaction with diaryl disulfides and trichloroisocyanuric acid in EtOAc.     

A convenient microwave-assisted synthesis of N-glycosyl amino acids

Optimization of coupling reactions of glycosylamines with Fmoc-protected aspartic acid, by microwave approach, is described. Different reaction conditions, quantities of substrates and solvents were tested to develop simple and reproducible methodologies. The best results were obtained using new triazine-based coupling reagents with a monomode microwave Discover® BenchMate™ instrument (CEM). The N-glycosyl amino acids were then deprotected to achieve final products for SPPS.     

Copper-catalyzed alkyne-aryne coupling reaction under microwave conditions: preparation of unsymmetric and symmetric di-substituted alkynes

Several unsymmetric and symmetric alkynes were prepared excellent to modest yields by generating benzyne from the reaction of 2-(trimethylsilyl)phenyl triflate with CsF in the presence of CuI and terminal alkyne under microwave heating for 30 min at 150 °C. Using conventional heating, the reactions required 24 h reaction time.     

A green synthesis of unsymmetrical triarylmethanes via indium (III) triflate catalyzed Friedel Crafts alkylation of o-hydroxy bisbenzylic alcohols under solvent free conditions

Using indium (III) triflate as a mild Lewis acid catalyst, the Friedel Crafts alkylation of o-hydroxy bisbenzylic alcohols with aromatic/heteroaromatic arenes under solvent free conditions was achieved to give the corresponding unsymmetrical triarylmethanes in high yields (up to 80% yield). Calculation of the different green metrics for the above reaction revealed it to have high atom economy (94–96%), high reaction mass efficiency (66–77%) and high carbon efficiency (70–80%). The Lewis acid was found to be air and moisture tolerant. The protocol was found to be operationally simple and can be carried out in an “open-flask” leaving behind water as the sole by product. Gratifyingly the Lewis acid catalyst could be recycled and reused up to 5 catalytic cycles without compromising much on the yield thus further highlighting the importance of the protocol.     

Microwave-assisted synthesis of 2-aminothiophene-3-carboxylic acid derivatives, 3H-thieno[2,3-d]pyrimidin-4-one and 4-chlorothieno[2,3-d]pyrimidine

A two-minute microwave irradiation allowed the synthesis of several 2-aminothiophene-3-carboxylic acid derivatives. Their efficient transformation to thieno[2,3-d]pyrimidin-4-one and the corresponding 4-chloro derivative is also reported under microwave irradiation.     

Selectfluor promoted environmental-friendly synthesis of 2H-chromen-2-ones derivatives under various reaction conditions

A simple, clean and benign route to the synthesis of 2H-chromen-2-ones derivatives through one-pot condensation of ??-ketoesters and substituted phenols in the presence of 1-chloromethyl-4-fluoro-1,4-diazoniabicyclo[2.2.2]octane bistetrafluoroborateis (Selectfluor? F-TEDA-BF₄) as catalyst under solvent free reaction conditions was experimented. The application of ultrasonic irradiation improved the yields and reduced the reaction times. The use of selectfluor catalyst is feasible because of its stability, commercial value, easy handling, easy recovery and good activity. To extend our research, the ability of selectfluor for the synthesis of 2-aminochromene derivatives was also examined.     

无溶剂条件下离子液体催化香豆素衍生物的绿色合成(英文)

Brnsted acidic ionic liquids, namely 2-pyrrolidonium hydrogen sulfate, N-methyl-2-pyrrolidonium hydrogen sulfate, N-methyl-2-pyrrolidonium dihydrogen phosphate, (4-sulfobutyl)tris(4-sulfophenyl)phosphonium hydrogen sulfate, and triphenyl(propyl-3-sulfonyl)phosphonium toluenesulfonate, catalyzed efficient Pechmann condensation of phloroglucinol with β-keto ethyl/ methyl esters. 5,7-Dihydroxy-4-methylcoumarin and 5,7-dihydroxy-4-phenylcoumarin were prepared in good to excellent yields under mild, ambient, and solvent-free conditions. Pyrano[2,3-h] coumarins were then prepared by one-pot three-component reactions of 5,7-dihydroxy-4-subsituted coumarin, malononitrile, and aldehydes in the presence of catalytic amounts of Br nsted basic ionic liquids, namely 2-hydroxyethylammonium formate, 3-hydroxypropanaminium acetate, 1-butyl-3-methylimidazolium hydroxide, pyrrolidinium formate, and pyrrolidinium acetate, under thermal solvent-free conditions. The catalysts are environmentally benign and can be easily prepared, stored, and recovered without significant loss of activity.     

Microwave-assisted rapid and efficient synthesis of C-alkyl imidazoisoquinolinone derivatives

The synthesis of a set of 10-benzyl-2,3-dihydroimidazo[1,2-b]isoquinolin-5(1H)-one and 5-oxo-imidazo[1,2-b]isoquinolin-10-yl)-N-phenylacetamide derivatives was achieved by exposing the corresponding alkylating agent and imidazoisoquinolinone to microwave irradiation and traditional oil bath heating in the presence of K₂CO₃ and DMAP. The microwave technique as well as DMAP as base accelerated the alkylation reaction for 2-6 min giving 79-88% yields.     

Mechanochemical synthesis of N-tert-butanesulfinyl imines under metal-free conditions

A simple and convenient mechanochemical method for the condensation of aldehydes with tert-butanesulfinamide using catalytic amounts of iodine under metal- and solvent-free conditions is described.     

One-pot synthesis of 2-amino-3-cyanopyridine derivatives under solvent-free conditions

A series of 2-amino-3-cyanopyridines were obtained from aryl aldehydes, substituted acetophenones, malononitrile and ammonium acetate in good to excellent yields by proceeding through a simple, mild and efficient procedure utilizing N,N,N′,N′-tetrabromobenzene-1,3-disulfonamide [TBBDA] and poly(N-bromo-N-ethylbenzene-1,3-disulfonamide) [PBBS] as catalysts.