The First One‐Pot,Solvent‐Free,Microwave‐Accelerated,Three‐Component Synthesis of Spirothiazolidin‐4‐ones via Staudinger/Aza‐Wittig Coupling/Cyclization

An efficient and rapid, solvent‐free, microwave‐accelerated, one‐pot, three‐component protocol for the synthesis of spirothiazolidin‐4‐ones from organic azides is reported for the first time via Staudinger/aza‐Wittig coupling/cyclization. The solvent‐free approach overcomes the limitations associated with the prevailing solution‐phase methodologies in the case of amines. In particular, its novelty is that it eradicates the vital limitation, i.e., the accumulation of H₂O (by‐product), which is known to affect the yield and rate of the reaction, thus affording the spirothiazolidin‐4‐ones in short reaction times in excellent yields.     

Iodine Catalyzed One‐pot Synthesis of 3,4‐Dihydroquinazolin‐4‐ones from Anthranilic Acids,Ortho Esters and Amines under Solvent‐free Conditions

A simple and efficient procedure has been developed for the one‐pot synthesis of 3,4‐dihydroquinazolin‐4‐ones from anthranilic acids, ortho esters and amines using a catalytic amount of iodine under solvent‐free conditions to afford the corresponding products in excellent yields. The direct use of commercially available catalyst, mild and solvent‐free reaction conditions, short reaction time, easy workup and excellent yields are the advantages of the present protocol.     

Stereoselective multicomponent synthesis of [3‐(5‐substituted 2‐methoxyphenyl)‐5‐aryl‐2‐phenyltetrahydro‐4‐isoxazolyl](2‐thienyl)methanones via 1,3‐dipolar cycloaddition

Three‐component stereoselective synthesis of a set of new tetra substituted isoxazolidines from 5‐substi‐tuted 2‐methoxybenzaldehydes, N‐phenylhydroxylamine and 1‐(2‐thienyl)‐3‐arylprop‐2‐en‐1‐ones has been achieved. The effect of microwave irradiation on the reaction under solvent‐free conditions has also been investigated. The stereochemistry of the final products has been confirmed by NMR and single crystal X‐ray analysis.     

One‐Pot Three‐Component Mild Synthesis of 2‐Aryl‐3‐(9‐alkylcarbazol‐3‐yl)thiazolidin‐4‐ones

A series of novel 2‐aryl‐3‐(9‐alkylcarbazol‐3‐yl)thiazolidin‐4‐ones were synthesized by one‐pot three‐component reactions of 3‐amino‐9‐alkylcarbazoles, aromatic aldehydes, and 2‐mercaptoacetic acid by using dicyclohexylcarbodiimide (DCC) as a cyclizing agent in dry diethyl ether at room temperature. This protocol has advantages of mild condition, short reaction time, high yield, and simple work‐up procedure.     

One‐Pot,Pseudo‐Five‐Component Synthesis of Bis[2‐(arylimino)‐1,3‐thiazolidin‐4‐ones]

Synthesis and characterization of bis[2‐(arylimino)‐1,3‐thiazolidin‐4‐ones] are described. The one‐pot, pseudo‐five‐component reaction of an aliphatic diamine, isothiocyanatobenzene, and dialkyl but‐2‐ynedioate at room temperature in anhydrous CH₂Cl₂ gives the title compound in relatively high yield. Under the same conditions, aromatic 1,2‐diamines yield 2‐(arylimino)‐N‐(enaminoaryl)‐1,3‐thiazolidin‐4‐ones in a pseudo‐four‐component reaction. Their structures were corroborated spectroscopically (IR, ¹H‐ and ¹³C‐NMR, and EI‐MS) and by elemental analyses. A plausible mechanism for this type of cyclization is proposed (Scheme 3).     

Regiospecific synthesis,structure and electron ionization mass spectra of 1,3‐thiazolidin‐4‐ones containing the acridine skeleton

The synthesis of regioisomeric 3‐alkyl(aryl)‐2‐(acridin‐9′‐yl)imino‐1,3‐thiazolidin‐4‐ones ( 8b‐i ) and 2‐alkyl(aryl)imino‐3‐(acridin‐9′‐yl)‐1,3‐thiazolidin‐4‐ones ( 11a‐i ) was performed by the reaction of 3‐(acridin‐9‐yl)‐1‐alkyl(aryl)thioureas 5a‐i with methyl bromoacetate and bromoacetyl bromide, respectively, via the corresponding isothiourea hydrobromides with excellent regioselectivity. The structure, NMR spectra and mass spectrometric behavior of the resulting compounds are discussed.     

Synthesis and ring transformation of substituted S‐(1‐phenylpyrrolidine‐2‐ones‐3‐yl)isothiuronium salts to substituted 2‐imino‐5‐[2‐(phenylamino)ethyl]thiazolidin‐4‐ones

Dedicated to Professor Jaromír Kaválek on the occasion of his 65^th birthday Substituted S‐(1‐phenylpyrrolidin‐2‐on‐3‐yl)isothiuronium salts in weakly basic media undergo intramolecular recyclisation reaction in which the γ‐lactam cycle is split and a thiazolidine cycle is formed. A series of six substituted 2‐imino‐5‐[2‐(phenylamino)ethyl]‐thiazolidin‐4‐ones have been prepared by this reaction.     

The Reactivity of Dimethyl Acetylenedicarboxylate and Heterocyclization of Hydrazinecarbothioamides to 1,3‐Thiazolidin‐4‐ones

2‐Substituted hydrazinecarbothioamides and N,2‐disubstituted hydrazinecarbothioamides react, in high yields with dimethyl acetylenedicarboxylate to give 4‐oxo‐Z‐(thiazolidin‐5‐ylidene)acetate derivatives. Several mechanistic options involving interaction are presented. The structures of thiazolidin‐4‐ones have been unambiguously confirmed by single crystal X‐ray crystallography.     

Solvent‐Free Synthesis of Heterocyclic Thioureas Using Microwave Technology

A new and rapid solvent‐free synthesis of heterocyclic thioureas in a microwave oven has been reported for the first time. Nine heterocyclic thioureas that possess biological activity have been synthesized. The reaction time is short (2–4.5 min) and gives excellent yields (82.9–95.5%).     

无溶剂条件下利用微波促进下的多组分反应对2,6-二芳基-4-苯乙烯基吡啶化合物进行非预期的绿色简易合成

在无溶剂条件下,通过微波促进下的3-芳基丙烯醛肟、1-芳基乙酮及醋酸铵的多组分反应,非预期地实现了2,6-二芳基-4-苯乙烯基吡啶化合物的绿色简易合成。该方法具有环境友好、反应时间短、产率高、成本低、操作简便以及适用范围广等优点。     

Green approach for the synthesis of 3‐methyl‐1‐phenyl‐4‐((2‐phenyl‐1H‐indol 3‐yl)methylene)‐1H‐pyrazole‐5(4H)‐ones and their DNA Cleavage,antioxidant, and antimicrobial activities

3‐Methyl‐1‐phenyl‐4‐((2‐phenyl‐1H‐indol‐3‐yl)methylene)‐1H‐pyrazol‐5(4H)‐ones (5a‐i) was prepared by the condensation reaction of different 3‐formyl‐2‐phenylindole derivatives (2a‐i) and 3‐methyl‐1‐phenyl‐2‐pyrazoline‐5‐one in quantitative yield by applying various green synthetic methods as grinding, microwave irradiation using different catalysts under solvent‐free mild reaction conditions with high product yields. The structures of the synthesized compounds were characterized on the basis of elemental analysis, infrared, ¹HNMR, ¹³C NMR, and mass spectral data. The synthesized compounds were screened for free radical scavenging, antimicrobial, and DNA cleavage activities. Most of the tested compounds belonging to the 3‐methyl‐1‐phenyl‐4‐((2‐phenyl‐1H‐indol‐3‐yl)methylene)‐1H‐pyrazol‐5(4H)‐ones series exhibited promising activities.     

Tandem synthesis of 2,3‐dihydroquinazolin‐4(1H)‐ones on grinding under solvent‐free conditions

Citric acid promoted synthesis of a mini‐library 2,3‐dihydroquinazolin‐4(1H)‐ones with good to excellent yields is achieved by tandem reaction of anthranilamides (or anthranilhydrazides) with aldehydes on grinding at room temperature under solvent‐free conditions. This method has notable advantages in terms of simple workup, short reaction time, cost‐effective, and environmentally benign. J. Heterocyclic Chem., (2012).     

Green Biginelli‐type Reaction: Solvent‐free Synthesis of 5‐unsubstituted 3,4‐dihydropyrimdin‐2(1H)‐ones

The Biginelli‐type compounds, 5‐unsubstituted 3,4‐dihydropyrimdin‐2(1H)‐ones were synthesized by a one‐pot three‐component condensation of aromatic aldehydes, aromatic ketones and urea in the presence of SnCl₄ · 5H₂O under solvent‐free conditions. The advantages of this method are short reaction time (4–10 min), excellent yields (74–97%), inexpensive catalyst and solvent‐free conditions. A plausible mechanism was proposed.     

Magnetized inorganic–bioorganic nanohybrid [nano Fe3O4‐SiO2@Glu‐Cu (II)]: A novel nanostructure for the efficient solvent‐free synthesis of thiazolidin‐2‐imines

In this research, a solvent‐free four‐component one‐pot reaction of phenyl isothiocyanate, phenylacetylene, various kinds of aldehydes, and amines was interpreted to obtain the desired five‐membered heterocycles named thiazolidin‐2‐imines. The promotor of this transformation is a novel magnetite‐based multilayered inorganic–bioorganic nanohybrid prepared via embedding glutamic acid on the magnetized silica followed by anchoring Cu (II) [nano Fe₃O₄‐SiO₂@Glu‐Cu (II)]. The newly synthesized nanostructure is characterized through Fourier‐transform infrared (FT‐IR), field‐emission scanning electron microscopy (FESEM), energy dispersive X‐ray analysis (EDAX), transmission electron microscopy (TEM), X‐ray fluorescence (XRF), thermogravimetric analysis or derivative thermogravimetric (TGA/DTG), vibrating sample magnetometer (VSM), X‐ray photoelectron spectroscopy (XPS), and Brunauer–Emmett–Teller (BET) techniques. This protocol is a straightforward one‐step procedure to obtain thiazolidin‐2‐imines without requirement to propargylamines or imines as substrates. In addition, easy work‐up procedure, high yields of products, absence of organic solvents in the reaction media, recovery and reusability of nano Fe₃O₄‐SiO₂@Glu‐Cu ( II) to promote the reaction at least for three runs without activity lost, simple separation of the catalyst from reaction mixture via an external magnet, and regioselectivity of the method are some highlighted aspects of the approach.     

18‐Crown‐6 Catalyzed Microwave‐mediated Synthesis of Symmetric Bis‐Heterocyclic Compounds under Solvent‐free Condition

An efficient, solvent‐free and 18‐crown‐6 catalyzed method for the synthesis of N‐alkyl‐4‐(4‐(5‐(2‐(alkyl‐amino)thiazol‐4‐yl)pyridin‐3‐yl)phenyl)thiazol‐2‐amine, N‐alkyl‐4‐(5‐(2‐alkyamino)thiazol‐4‐yl)pyridine‐3‐yl)thiazol‐2‐amine, and 4,4′‐bis‐{2‐[amino]‐4‐thiazolyl}biphenyl bis‐heterocyclic derivatives via microwave accelerated cyclization is presented.     

Efficient microwave‐assisted synthesis and antioxidant activity of 4‐arylidene‐2‐phenyl‐1H‐imidazol‐5(4H)‐ones

The efficient synthesis of 4‐arylidene‐2‐phenyl‐1H‐imidazol‐5(4H)‐ones was achieved via microwave‐assisted reactions of 4‐arylmethylene‐2‐phenyloxazol‐5(4H)‐ones with urea in glycol. This approach provides a facile shortcut for the synthesis of this type of compounds with short reaction time, high yields, broad substrate scope and easy operation. Besides, the synthesized compounds were subject to the test of antioxidant activity, which is represented by their capacities for scavenging 1,1‐diphenyl‐2‐picrylhydrazyl, hydroxyl and superoxide anion free radicals. Bioassay of these compounds resulted in the finding of several 4‐arylidene‐2‐phenyl‐1H‐imidazol‐5(4H)‐ones with significant antioxidant activity. J. Heterocyclic Chem., (2012).     

Functionalized Benzofurans via Microwave‐Promoted Tandem Claisen‐Rearrangement/5‐endo‐dig Cyclization

Ortho‐allyloxy alkinyl benzenes undergo, upon microwave irradiation in dimethylformamide, a tandem sequence of Claisen‐rearrangement and 5‐endo‐dig cyclization to furnish 7‐allyl‐substituted benzofurans. With terminal alkynes, chroman‐4‐ones and enaminoketones become the main products. A mechanistic proposal for this observation relies on a reaction of the starting material with the solvent dimethylformamide under the microwave conditions.     

A Green,Solvent‐Free,Microwave‐Assisted,High‐Yielding YbCl3 Catalyzed Deprotection of THP/MOM/Ac/Ts Ethers of Chalcone Epoxide and 2′‐Aminochalcone and Their Sequel Cyclization

Under microwave and solvent‐free conditions, YbCl₃ efficiently catalyzed the deprotection of tetrahydropyran‐2‐yl, methoxymethyl (MOM), acetyl, and tosyl groups and sequel cyclization of chalcone epoxide to 2‐hydroxyindanone and 2′‐aminochalcone to aza‐flavanone. The reaction afforded the products in excellent yield (78–99%) at 850 W microwave heating within 1–5 min under eco‐friendly conditions. The merits of the presented protocol include high yield, use of microwave irradiation, solvent‐free condition, catalyst reusability, and no need for purification with column chromatography. The present method is very much milder but more advanced than those reported earlier.     

An efficient and facile ultrasonic‐accelerated one‐pot synthesis of N‐acetyl‐2‐aryl‐1, 2‐dihydro‐(4H)‐3,1‐benzoxazin‐4‐ones

An application of ultrasonic irradiation in the one‐pot synthesis of N‐acetyl‐2‐aryl‐1,2‐dihydro‐(4H)‐3,1‐benzoxazin‐4‐ones from the condensation reaction between aromatic aldehydes and anthranilic acid in the presence of excess amount of acetic anhydride has been explored. The reactions proceed smoothly under mild and solvent‐free conditions at room temperature in the absence of any catalyst to afford the products in good to excellent yields. © 2011 Wiley Periodicals, Inc. Heteroatom Chem 22:106–113, 2011; View this article online at wileyonlinelibrary.com . DOI 10.1002/hc.20663     

Synthesis,Characterization, Antibacterial,and Antifungal Activity of Novel 2‐(2‐hydroxy‐5‐((aryl)‐diazenyl)phenyl)‐3‐(4‐hydroxyphenyl)‐thiazolidin‐4‐one

A series of novel thiazolidinones, that is, 2‐(2‐hydroxy‐5‐((aryl)‐diazenyl)phenyl)‐3‐(4‐hydroxyphenyl)‐thiazolidin‐4‐one, have been synthesized by reaction of various Schiff bases 2‐(4‐hydroxyphenylimino)methyl)‐4‐(aryl)diazenyl)phenol with ethanolic thioglycolic acid. Schiff bases were obtained by the reactions of 4‐amino phenol with 2‐hydroxy‐5‐((aryl)diazenyl)benzaldehyde. The structures of the newly synthesized compounds were confirmed by IR, ¹H NMR, mass spectra, and C, H, N elemental analysis. The thiazolidinone derivatives were evaluated for their antibacterial and antifungal activity.