Synthesis of Spirooxindoles through Cyclocondensation of Isatin and Cyclic 1,3‐Diones

A simple, clean, and efficient method for the synthesis of spirooxindole derivatives via condensation of isatin with enolizable cyclic β‐diketones has been developed. The use of water as a solvent allows avoiding the use of toxic organic solvents, which makes this reaction safe and environmentally friendly. The mechanism of the condensation reaction has been investigated using first‐principles‐based density functional theory calculations.     

[BMIM]Cl Catalyzed One‐Pot Synthesis of α‐Aminophosphonate Derivatives Containing a 4‐Phenoxyquinazoline Moiety under Microwave Irradiation

[BMIM]Cl catalyzed three component Mannich‐type reaction of 4‐(quinazolin‐4‐yloxy)benzenamine and aldehyde with dialkyl phosphite under microwave irradiation has been described. The salient features of the reaction leading to new α‐aminophosphonates include shorter reaction time and good yields. The method is environmentally friendly and does not require toxic catalysts or solvents. To the best of our knowledge, this is the first report for [BMIM]Cl induced one‐pot synthesis of α‐aminophosphonate derivatives.     

Solid Supported Synthesis of New 2,4‐Dithioxo‐6‐aryl‐3‐(1′,3′,4′‐thiadiazolo)‐1,3,5‐triazines Using Microwaves

A series of novel 2,4‐dithioxo‐6‐aryl‐3‐(1′,3′,4′‐thiadiazolo)‐1,3,5‐triazines have been synthesized from 1,3,4‐thiadiazolo‐thioureas and arylaldehydes using microwave irradiations (MWI) over inorganic solid supports. The yield afforded in microwave reactions was 80% whereas it was 60% in conventional reactions. Solid supported synthesis using microwaves has eliminated the usage of toxic substances and organic solvents except for the limited consumption of methanol and ethanol in pre and post reaction stages. This methodology has been proved an efficient, facile, rapid, and ecofriendly synthetic technology.     

Asymmetric Synthesis of trans‐β‐Lactams by a Kinugasa Reaction on Water

The asymmetric Kinugasa reaction was performed on pure water for the first time without the need for any organic co‐solvents. In contrast to most asymmetric Kinugasa reactions, trans‐β‐lactams were obtained as the major products in good yields, enantioselectivities, and diastereoselectivities (up to 90 % yield, 98 % ee, and >99:1 d.r.). This reaction is atom‐economical, environmentally friendly, and affords synthetically useful but challenging products.     

A One‐pot,Efficient Synthesis of Polyfunctionalized Pyrido[2,3‐d]pyrimidines and Uncyclized Adducts by Aldehydes, 1,3‐Dicarbonyl Compounds,and 6‐Aminouracils

A one‐pot, efficient protocol for the synthesis of polyfunctionalized pyrido[2,3‐d]pyrimidines and uncyclized adducts by 6‐aminouracils in poly(ethylene glycol) 200/H₂O or AcOH was described. An interesting family of pyrido[2,3‐d]pyrimidines and uncyclized adducts bearing fused pharmacological active units are prepared. The reaction is free of toxic solvents and catalysts, has simple workup procedure, and has high atom economy, making it more environmentally friendly and suitable for large‐scale operations.     

Water‐Based Synthesis of Novel 6, 7‐Dihydrobenzofuran‐4 (5H) ‐Ones

A simple, efficient, and high yielding one‐pot protocol for the synthesis of 4‐keto‐4,5,6,7‐tetrahydrobenzofurans has been developed by three‐component coupling reaction of dimedone, phenylglyoxal monohydrate, and heteroaryl amines in eco‐friendly solvent water under reflux conditions. The protocol avoids the use of catalysts, toxic solvents, tedious work‐up procedures, and chromatographic separation. The reaction proceeds at fast rates within 45 min and provides access to a variety of fused‐ring furans in high to excellent yields.     

An Environmentally Benign Water Promoted Catalyst Free Highly Efficient,One‐pot Synthesis of 2‐Imino‐4‐thiazolidinone

A practical and efficient protocol has been developed for the synthesis of 2‐imino‐4‐thiazolidinone through a unique one pot three‐component reaction of variety of amines, isothiocyanate and ethylbromoacetate in water. The method is free of catalyst and other toxic solvents, has shorter reaction times, high‐yielding, effortlessness in isolation of product, making it more eco‐friendly process, and suitable for large scale operation.     

Three‐Component Uncatalyzed Eco‐Friendly Reactions for One‐Pot Synthesis of 4,7‐Dihydro[1,2,4]triazolo[1,5‐a]pyrimidine Derivatives

A three‐component system of one‐pot synthesis of [1,2,4]triazolo[1,5‐a]pyrimidine derivatives using condensation of 1,3‐dicarbonyl compounds, aldehydes, and 5‐amino[1,2,4]triazole in ethanol without any catalyst was reported in high yields via simple, efficient, and environmentally friendly process. The method reported herein considered a green process; this method has significant advantages of simple workup procedure, excellent yield, minimal environmental pollution, and short reaction time over classical reported methods.     

One‐pot synthesis of pyrano‐ and furanoquinolines catalyzed by molten tetra‐n‐butylphosphonium bromide under solvent‐free conditions

Molten tetra‐n‐butylphosphonium bromide is found to be a practical and inexpensive catalytic media for stereoselective one‐pot synthesis of pyranoquinoline and furanoquinoline derivatives in good to excellent yields. Products of undesirable reactions resulting from polymerization are not observed. The use of this catalyst media avoids the use of any cocatalysts or toxic organic solvents. J. Heterocyclic Chem., (2011).     

Synthesis of Conjugated Polyphenylene Dendritic β-Diketones

An efficient synthesis of high generation conjugated polyphenylene dendrimer-based β-diketones was investi- gated using simple synthetic methods. The new dendrimer-based β-diketones were characterized by NMR, MS and elemental analysis. The UV-Vis and fluorescence spectra of these β-diketones in different solvents were investigated The photoluminescent （PL） quantum yield and TG and DSC curves were also investigated. A new intermediate, 1-bromo-3,5-diiodobenzene, was developed to synthesize high generation dendrimers with good yields.     

Conjugated Polymers Via Direct Arylation Polymerization in Continuous Flow: Minimizing the Cost and Batch‐to‐Batch Variations for High‐Throughput Energy Conversion

Continuous flow methods are utilized in conjunction with direct arylation polymerization (DArP) for the scaled synthesis of the roll‐to‐roll compatible polymer, poly[(2,5‐bis(2‐hexyldecyloxy)phenylene)‐alt‐(4,7‐di(thiophen‐2‐yl)‐benzo[c][1,2,5]thiadiazole)] (PPDTBT). PPDTBT is based on simple, inexpensive, and scalable monomers using thienyl‐flanked benzothiadiazole as the acceptor, which is the first β‐unprotected substrate to be used in continuous flow via DArP, enabling critical evaluation of the suitability of this emerging synthetic method for minimizing defects and for the scaled synthesis of high‐performance materials. To demonstrate the usefulness of the method, DArP‐prepared PPDTBT via continuous flow synthesis is employed for the preparation of indium tin oxide (ITO)‐free and flexible roll‐coated solar cells to achieve a power conversion efficiency of 3.5% for 1 cm² devices, which is comparable to the performance of PPDTBT polymerized through Stille cross coupling. These efforts demonstrate the distinct advantages of the continuous flow protocol with DArP avoiding use of toxic tin chemicals, reducing the associated costs of polymer upscaling, and minimizing batch‐to‐batch variations for high‐quality material.     

Polymer‐Supported Sulfonic Acid‐Catalyzed Candid Synthesis and Photophysical Properties of 2H‐indazolo[2,1‐b]phthalazinetriones

Polystyrene‐supported sulfonic acid has been found to be an efficient catalyst for the one‐pot, three‐component synthesis of 2H‐indazolo[2,1‐b]phthalazinetriones in greener solvent glycerol. Use of greener solvent glycerol along with a polymer‐supported, low toxic, and inexpensive catalyst renders the method eco‐friendly. High yields, simple product isolation procedure, and fluorescent and electroluminescent natures of the products are the noteworthy aspects of this protocol.     

A Green Approach for the One‐Pot,Three‐Component Synthesis of 2‐Arylpyrroloacridin‐1(2H)‐Ones using Lactic Acid as a Bio‐based Catalyst under Solvent‐Free Conditions

A facile and benign synthetic strategy is proposed for the synthesis of 2‐arylpyrroloacridin‐1(2H )‐ones via a lactic acid‐catalyzed three‐component reaction of dimedone, various anilines, and isatins under solvent‐free conditions. Avoidance of hazardous organic solvents, the use of a one‐pot multicomponent procedure for the synthesis of 2‐arylpyrroloacridin‐1(2H )‐ones, operational simplicity, no need for column chromatography, lactic acid utilization as a bio‐based organic compound, reusability, homogeneity, and commercial availability of the catalyst, and superior synthetic performance are some important aspects of this methodology to access a series of pyrroloacridine motifs with potentially biological scaffolds.     

One‐Pot Three‐Component Synthesis of 2‐Amino Pyrimidines in Aqueous PEG‐400 at Ambient Temperature

Amino pyrimidines have been synthesized by a one‐pot procedure under environmentally friendly reaction conditions at room temperature. The use of aqueous PEG‐400 circumvents the problems associated with the toxic, hazardous organic solvents and oxidizing agents.     

Making Solid‐Phase Peptide Synthesis Greener: A Review of the Literature

To date, the synthesis of peptides is concurrent with the production of enormous amounts of toxic waste. DMF, CH₂Cl₂, and NMP are three of the most toxic organic solvents used in chemical synthesis and are the most common solvents used for peptide synthesis. Additionally, concerns about the hepatotoxicity caused by exposure to DMF and from the toxic and allergenic nature of additives used in peptide synthesis necessitates the need for a green, environmentally friendly, and safer protocol for peptide synthesis. This review summarizes the current literature on green solid‐phase peptide synthesis successes and challenges encountered. The review concludes with suggestions for future research towards a simple and efficient green peptide synthesis protocol.     

Facile synthesis of 1, 2‐benzisothiazole‐3‐one‐1,1 ‐dioxide methylsulfonyl derivatives

An improved and general synthesis of saccharin methylthio and methylsulfone derivatives from chlorosubstituted saccharins is presented. A large‐scale procedure for preparation of chloro‐substituted saccharins was developed. Treatment of the saccharin chlorides with sodium thiomethoxide and t‐BuOK in DMF gave the saccharin methyl sulfides, which upon chromium(VI) oxide catalyzed oxidation with periodic acid afforded the corresponding saccharin methylsulfones in high yields.     

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.     

Asymmetric Syntheses of 2‐(1‐Aminoethyl)phenols

Three different routes were probed for the synthesis of enantiomerically enriched 2‐(1‐aminoethyl)phenols and their methyl ethers. The first route centers on diastereoselective nucleophile addition to chiral imines. The second route has as key steps the enantioselective reduction of a ketone followed by nucleophilic substitution, and the third route involves a diastereoselective imine reduction. The efficiency of the approach depends on the substrate substitution pattern. All three methods work well for the parent compound 2‐(1‐aminoethyl)phenol ( 1 ) but the third route is the most efficient, providing the compound with >96% enantiomer excess in three steps with an overall yield of 71%. Conversely, for the ortho‐methyl analogue 2 , the first method is best. For the t‐Bu‐substituted analogue 3 , only moderate enantiomeric enrichment was achieved.     

Low Bandgap Semiconducting Copolymer Nanoparticles by Suzuki Cross‐Coupling Polymerization in Alcoholic Dispersed Media

The synthesis and formulation of organic semiconductors for the emerging technology of organic electronics requires the use of preparative methods and solvents being environment friendly. Today most of the active layer materials for the organic photovoltaic devices and modules are using chlorinated solvents, which are toxic and hazardous. In this work, the synthesis of poly[N‐9′‐heptadecanyl‐2,7‐carbazole‐alt‐5,5‐(4,7‐di‐2‐thienyl‐2′,1′,3′‐benzothiadiazole] (PCDTBT) in propan‐1‐ol is presented as the dispersant continuous phase in the presence of poly(vinylpyrrolidone) used as stabilizer. Suzuki–Miyaura polycondensation of 9‐(9‐heptadecanyl)‐9H‐carbazole‐2,7‐diboronic acid bis(pinacol) ester and 4,7‐bis(2‐bromo‐5‐thienyl)‐2,1,3‐benzothiadiazole in alcohol dispersion yields colloidally stable nanoparticles of PCDTBT with particles size of 330–1300 nm, depending on the stabilizer concentration. Other reaction parameters are also discussed such as the amount of base or Pd catalyst.

     

Synthesis of Nitrile‐Bearing Quaternary Centers by an Equilibrium‐Driven Transnitrilation and Anion‐Relay Strategy

The efficient preparation of nitrile‐containing building blocks is of interest due to their utility as synthetic intermediates and their prevalence in pharmaceuticals. As a result, significant efforts have been made to develop methods to access these motifs which rely on safer and non‐toxic sources of CN. Herein, we report that 2‐methyl‐2‐phenylpropanenitrile is an efficient, non‐toxic, electrophilic CN source for the synthesis of nitrile‐bearing quaternary centers by a thermodynamic transnitrilation and anion‐relay strategy. This one‐pot process leads to nitrile products resulting from the gem‐difunctionalization of alkyl lithium reagents.