Good Yields Research Articles

Regioselective Synthesis of Cycloalkane-fused Pyrazolo[4,3-e]pyridines through Tandem Reaction of 5-aminopyrazoles, Cyclic Ketones and Electron-rich Olefins.

Pyrazolopyridines are interesting fused heterocyclic pharmacophores that combine pyrazole and pyridine; two privileged nuclei extensively studied and with a wide range of applications. They can be obtained by a broad variety of synthetic methods among which multicomponent reactions have gained importance, especially from 5-aminopyrazoles and dielectrophilic reagents. However, the search for new approaches more in tune with sustainable chemistry and the use of unconventional heating in three-component synthesis are open and highly relevant study fields. A novel, practical and efficient three-component synthesis of cycloalkane-fused pyrazolo[ 4,3-e]pyridines was developed through a tandem reaction of 5-aminopyrazoles, cyclic ketones and electron-rich olefins, using microwave induction in perfluorinated solvent and iodine as catalyst. The microwave-induced three-component approach applied in this work promoted the construction of 10 new pyrazolopyridines with high speed and excellent control of regioselectivity, favoring the linear product with good yields; where the versatility of electron-rich olefins in iodine-catalyzed cascade heterocyclizations, granted the additional benefit of easy isolation and the possibility to reuse the fluorous phase. Although pyrazolopyridines have been synthetically explored because of their structural and biological properties, most of the reported synthetic methods use common or even toxic organic solvents and conventional heating or multi-step processes. In contrast, this study applied a multicomponent methodology in a single step by microwave induction and with the versatility provided in this case by the use of perfluorinated solvent, which allowed easy isolation of the final product and recovery of the fluorous phase.

Design, Synthesis, QSAR Studies, and Molecular Modeling of Some Novel Bis Methyl 2-[3-(benzo[d]thiazol-2-yl)-2-terephthaloyl-bis-4-oxo-thiazolidin- 5-ylidene]acetates and Screening of their Antioxidant and Enzyme Inhibition Properties.

Benzothiazolamine-based bisthiourea precursors were prepared in good yields. These bisthiourea derivatives were cyclized into symmetrical Bis Methyl 2-[3-(benzothiazol- 2-yl)-2-terephthaloyl-bis-4-oxo-thiazolidin-5-ylidene]acetates, by their condensation with (DMAD) dimethyl but-2-meditate in the presence of dry methanol. All these compounds were evaluated for their biological applications. Antioxidant activities were performed by adopting a DPPH radical assay, and an in vitro enzyme inhibition assay was performed to investigate their enzyme inhibitory potential against butyrylcholinesterase (BChE) and acetylcholinesterase (AChE). Molecular modeling and QSAR studies were performed to monitor the binding propensity of imidathiazolidinone derivatives with enzymes and DNA. Also, electronic and steric descriptors were calculated to determine the effect of structure on the activity of imidathiazolidinone derivatives. The characterization of all the synthesized compounds was done by their physical data, FT-IR, NMR and elemental analysis.

EMIM] [OAc]: An Efficient Ionic Liquid Medium for the Synthesis of New 4-(furan/pyrrole/thiophene-2-yl)-3, 4-dihydro-1H-chromeno [4,3-d] pyrimidine-2,5-diones and Molecular Docking Studies

Abstract: An efficient synthesis of Chromeno[b]pyrimidine derivatives 4 has been achieved by treating 4-hydroxy-2H-chromen-2-one 1, furan-2-carbaldehyde / 1H-pyrrole-2-carbaldehyde/ thiophene-2- carbaldehyde 2, and urea/thiourea 3 at 65-70 °C for 90-120 min using 1-Ethyl-3-methylimidazolium acetate as ionic liquid and medium with good yields 86-90%. This synthetic method has numerous advantages, including high yields, a simple protocol, environmental friendliness, brief reaction times, and mild reaction conditions. Using a catalytically active ionic liquid as the medium eliminates the need for a catalyst and a solvent. In this study, the docking score of the synthesized compounds was found to be between -8 to -9 kcal/mol similar to the co-crystal. Additionally, the compounds maintained their amino acid interactions with Tyr 281 (coagulation protein; 6WV3) and Thr 179 (tubulin polymerization protein; 5LYJ.pdb).

Visible Light-Driven Metal- and Photocatalyst-Free Synthesis of β-Trifluoromethylated Enamines via Trifluoromethyl Thianthrenium Salts.

A novel protocol for the visible-light-driven synthesis of β-trifluoromethylated enamines has been developed, which operates without the use of transition metals or any photocatalysts, utilizing trifluoromethylthiosulfonium salts as the source of trifluoromethyl groups under mild conditions. According to this new protocol, more than 40 products have been prepared in moderate to good yields. In addition to eliminating the need for expensive or toxic transition metals and photocatalysts, this new methodology proves its potential scalability through air-stability, the use of safe and readily available reagents, a two-step one-pot procedure, and effective gram-scale reactions. This innovative approach not only demonstrates promise for green chemical synthesis but also offers a new pathway for the advancement of fluorine chemistry in sustainable organic synthesis.

Solvent-Controlled Divergent Cyclization of 3-Ylideneoxindoles with Ethyl 2-Diazoacetate: Access to Spirocyclopropyl and Spiropyrazolines Oxindoles.

Herein a catalyst-free solvent-controlled method for the divergent synthesis of spirocyclopropyl and spiropyrazoline oxindoles from 3-ylideneoxindoles and ethyl diazoacetate was developed. With ClCH2CH2Cl as the solvent, spirocyclopropyl oxindoles were obtained in moderate to excellent yields, whereas the use of MeOH as solvent afforded spiropyrazoline oxindoles in moderate to good yields. The readily available substrates, simple operation and various product transformations further highlighted the utility of this method.

Palladium-Catalyzed Synthesis of Substituted Phenanthrenes via a C-H Annulation of 2-Biaryl Triflates with Alkynes.

A new palladium-catalyzed efficient method for the synthesis of substituted 9,10-phenanthrenes from 2-biaryl triflates with alkynes has been developed. This method provides a great opportunity to prepare various symmetrical and unsymmetrical phenanthrene derivatives in good yields. This reaction proceeds via C-OTf bond cleavage and alkyne insertion followed by C-H annulation.

Intramolecular/Intermolecular Sequential Cyclization Accompanied by Double C-F Bond Cleavage: Access to Tricyclic Fluorine-Containing Pyrano[3,2-c]chromenes.

Defluorinative cyclization of CF3-alkenes has emerged as a reliable strategy for crafting intricate polycyclic frameworks. In this study, a facile defluorinative bicyclization approach was developed for the construction of 4H,5H-pyrano[3,2-c]chromenes under mild conditions involving a sequence of intramolecular cyclization and intermolecular defluoroheterocyclization. A variety of polysubstituted 4H,5H-pyrano[3,2-c]chromenes featuring C2-fluorine could be synthesized in good yields with excellent tolerance toward various functional groups. Moreover, the introduction of a C-F bond provides additional possibilities for further modification of this skeleton. The product features aggregation-induced emission (AIE) characteristics after simple modification, which is promising for chemical and biomedical imaging.

A Novel Synthesis Route of Phenyl Quinoline from Nitrochalcone with Hydrazine Hydrate in the Presence of Pd/C

Quinoline is widely known to have many biological activities. Therefore, the development of the synthesis method of a quinoline derivative framework is a priority. A phenyl quinoline derivative, 6,7-dimethoxy-2-phenylquinoline Q1, has been successfully synthesized via a novel one-pot reaction that involves reduction, cyclization, and followed by dehydration of nitrochalcone derivate, 3-(4,5-dimethoxy-2-nitrophenyl)-1-phenylprop-2-en-1-one C1. The reaction was carried out using 80 % hydrazine hydrate in the presence of 10% Pd/C as a catalyst in an ethanol medium. Target compound Q1 was afforded in a good yield of 69.18% in a relatively short reaction time of ±2 h.

ZIF‐67 Derived Cobalt Catalysts for the Hydroformylation of Liquid Olefins

AbstractIn this work, we described a general monometallic cobalt heterogeneous catalyst for the hydroformylation of olefins, achieving good yields and recyclability up to five times with no loss in catalytic activity. These catalysts were prepared through the pyrolysis of the well‐defined metal–organic framework ZIF‐67. The addition of steam during the pyrolysis did not affect the final phase composition of the cobalt particles; nonetheless, it resulted in an increase of the cobalt particle size and the partial removal of the carbonaceous matrix. The materials were extensively characterized by several techniques, and it was observed that the N‐doped carbon matrix played a crucial role in terms of activity and stability. Different liquid olefins, including internal, terminal, and cyclic were successfully tested in our hydroformylation protocol. Aldehydes yields of 48%–77% for different liquid olefins were achieved with the optimal catalyst. No leaching of the active sites was observed over five catalytic cycles. The high stability of the catalyst is attributed to the presence of stabilizing nitrogen atoms bearing the cobalt sites.

Synthesis of Diketopyrrolopyrrole Based Photoactive Materials via Photoredox C−H Activation

AbstractThe synthesis of diketopyrrolopyrrole (DPP) derivatives followed the well‐known conventional cross‐coupling methods such as Suzuki, Stille, Sonogashira, and Negishi cross‐coupling reactions. However, these methods required unfavorable reaction conditions, organometallic precursors, and high temperatures. In addition, the synthesis of conventional cross‐coupling partners including organoboranes, stannane, and acetylenes required drastic reaction conditions and strong bases. In this work, a wide variety of thiophene‐diketopyrrolopyrrole (TDPP)‐based semiconducting materials (36 compounds) were synthesized via Pd‐catalysed photoredox methodology by using N‐hydroxyphthalimide (NHP) based coupling partners, which can be readily prepared from N‐hydroxyphthalimide and carboxylic acid or aldehyde derivatives via single step C−O bond formation reactions with good yield (80–90 %). This methodology minimizes additional synthetic steps, harsh reaction conditions, and high temperature (100–150 °C). Optoelectronic studies suggest that the synthesized materials have suitable band gap, HOMO and LUMO levels for variety of optoelectronic applications. To the best of our knowledge, this is the first report on the synthesis of TDPP‐based π‐conjugated materials via the photoredox method.

NiII, PdII and PtII pincer complexes of 2-(diphenylphosphanyl)-N-(2-(diphenyl-phosphanyl)benzyl)benzamide: synthesis, reactivity and catalytic studies.

In this article, the synthesis of bis(phosphine), o-Ph2PC6H4C(O)N(H)CH2C6H4PPh2-o (1) (hereafter referred to as "PCNHCP" and its anionic form as "PCNCP") and its group 10 metal chemistry and catalytic studies are described. PCNHCP (1) on reaction with NiCl2(DME) and PdCl2(COD) afforded pincer complexes, [MCl{(PCNCP)κ3-P,N,P}] (M = Ni, 2; Pd, 3). A similar reaction of 1 with PtCl2(COD) yielded a chelate complex, [PtCl2{(PCNHCP)κ2-P,P}] (4), which on further treatment with LiHMDS produced the 1,2-azaphospholene-phosphine complex, [PtCl(Ph){(o-P(Ph)C6H4CONCH2C6H4PPh2-o)κ2-P,P}] (5) via P-C/P-N bond metathesis. Passing dry HCl gas through the solution of 5 resulted in benzene elimination to form [PtCl2{(o-P(Ph)C6H4CONCH2C6H4PPh2-o)κ2-P,P}] (6). Treatment of 1 with PtCl2(COD) and Pt(Cl)(Me)(COD) in the presence of a base resulted in pincer complexes [PtX{(PCNCP)κ3-P,N,P}] (X = Cl, 7; Me, 8). Nickel complex 2 catalyzed the Suzuki-Miyaura cross coupling reaction between bromobenzene and phenyl boronic acid to give the corresponding biphenyls in good yield. The platinum complex 5 showed good catalytic activity towards regio- and stereoselective hydroboration of terminal alkynes. Both the catalytic reactions were performed under mild reaction conditions with a very low catalyst loading.

Nitrogenation of Alkynes with Nitrones to Prepare Functionalized [1,4]Oxazinones through Csp-Csp2 Bond Cleavage.

Herein, we report a novel strategy of hypervalent iodine(III) compound-mediated selective Csp-Csp2 bond cleavage of alkynes and C═N/N-O bond cleavage of nitrones and recombination of C-C/C-O/C-N multiple bonds to access various functionalized [1,4]oxazinones bearing a vicinal carbon stereocenter in good yields and high diastereoselectivity. Mechanistic studies revealed that the reaction undergoes a domino [4 + 3] cycloaddition, 1,3-rearrangement of N-O bond, intramolecular cyclization, dearomatization, and rearomatization over four steps in a single flask. The present method features good functional group tolerance, broad substrate scope, and C-C/C═N/N-O multiple bonds cleavage and recombination.

Photochemical Fluoroalkylation and Alkylthiolation of O‐Cyano and O‐Alkynyl Acrylamides: Pendant Functionality Led Divergence in Annulations

AbstractA visible‐light‐mediated, organophotocatalyzed cascade perfluoroalkylation and alkylthiolation of o‐cyano and o‐alkynyl acrylamides is reported. The reaction exhibits wide scope and provides polyfluorinated 1,3‐quinoline diones and trifluoromethylated fused tricyclic quinolinones under mild reaction conditions and in good yields. Access to a variety of molecular architectures and the synthetic application of aliphatic thiols are the highlights of this reactivity manifold.

Punjab Tar-1: A New Short Duration, High Yielding and Disease Resistance Long Melon Variety (Cucumis melo) Released in Pakistan.

The development of new crop varieties with favorable features is a continuing effort. With the passage of time, a cultivated variety becomes subjected to various biotic and abiotic plant stresses. This article describes development of an innovative and imaginative long melon cultivar called "Punjab Tar-1."This article discusses creation of a novel and inventive long melon variety known as "Punjab Tar-1." Current long melon varieties in Pakistan are sensitive to climatic conditions and susceptible to pest and disease attack. A New Short Duration, High Yielding and Disease Resistance Long Melon Variety (Cucumis melo) is released in Pakistan to address these current issues of long melon varieties A high yielding and early maturing variety of long melon “Punjab Tar-1” has been developed by Vegetable Research Institute, Faisalabad, Pakistan through mass selection. Plants were selected from an open pollinated indigenous source population with main emphasis on earliness, fruit shape, color and taste and yield. Selection intensity was 15% in 1st three selection cycles and 30% in subsequent four selection cycles whereas yield trials were started from 8th selection cycle. The fruit of this variety has a strong longitudinal rib that makes it difficult for eating by caterpillars. This variety has wide adaptability and exhibits stable yield across multiple environments. Notably, "Punjab Tar-1" contains 10.59 % crude protein and 1.08% crude fat content. Genetic uniformity and distinctiveness of this variety was confirmed through SSR polymorphism. Punjab Tar-1 variety has been approved by Punjab Seed Council in its meeting held on 2021 and was recommended for general cultivation in Punjab, Pakistan. Its certified seed is available for farmers at Vegetable Research Institute, Faisalabad. This newly approved variety will aid to save the precious foreign reserves by reducing vegetable seed import bill. In Pakistan, seed market of long melon is occupied by improved varieties. In multi-location evaluation, one said variety has exhibited high yield and stability than exotic germplasm. This is the first variety developed in Pakistan having good taste, early maturity, long shape, and high yield potential. DNA fingerprinting has further confirmed that it is distinct from local material, having novelty and diversity.

Green extraction of colorants from achiote seeds for dyeing mordanted nylon fabric

The extraction of sustainable colorants requires energy efficient technology for their eco-application in different fields. For current study on nylon fabric, the natural dye from achiote (Bixa orellana) has been extracted in aqueous and acidic media and valorized through microwave (MW) radiation. MW treatment has been applied to both extracted biomolecule and nylon fabric up to 10 min and the dyeing variables were optimized using statistical model. For getting permanent shades eco-salts of Al (III) and Fe (II) as well as biomolecules from waste plant materials (pomegranate and myrobalan) were utilized. ISO methods for assessment of colorfast shades have been employed. It was found that for nylon, by MW treatment of the dye material and polymeric stuff for 4 min, good color yield in terms of color strength (K/S=29.52) is obtained. It has been observed that when MW treated extract (pH=6) is employed at 40 °C for 55 min, good quality shade of high strength is obtained by using selected amounts of eco-chemical and organic molecules. It is concluded that MW treatment should be given to dyeing process for getting effective yield and tannin based green molecules as organic mordant can used to make dyeing process more ecofriendly and sustainable.

Direct Substitution of 2‐Aminotropones with Potassium Allyltrifluoroborates through Transition‐Metal‐Free C−N Bond Cleavage

AbstractThe poor nucleofugality of the amino group renders the C−N bond functionalization of primary aromatic amines highly challenging. Herein, we report a direct substitution reaction of 2‐aminotropones, bearing a unique non‐benzenoid seven‐membered aromatic ring that exists in some natural products and bioactive molecules, with potassium allyltrifluoroborates through C−N bond cleavage under transition‐metal‐free conditions. The amino group of 2‐aminotropones were directly substituted with potassium allyltrifluoroborates in the presence of sodium bicarbonate, delivering structurally diverse 2‐allyltropones in moderate to good yields. The reaction is free of directing groups, activating groups and transition metals, providing a convenient method to access substituted tropones.

Facile and Metal‐Free Synthesis of Isoflavones Using α‐Aryl‐β,β‐Ditosyloxy Ketones

AbstractConsidering the drawbacks associated with available synthetic methodologies of isoflavones, herein we have reported a metal‐free and eco‐friendly approach to these natural products. In the present study, we have carried out the synthesis of eight isoflavone derivatives 7a–7h using α‐aryl‐β,β‐ditosyloxy ketone protocol. Initially, we have protected the 2’‐hydroxy group of respective chalcone moiety in order to remove its interference under reaction conditions. The protected chalcones were then subjected to 1,2‐aryl migration by being treated with hydroxy(tosyloxy)iodobenzene (HTIB) reagent in a non‐nucleophilic solvent (CH2Cl2). This migration furnished the formation of α‐aryl‐β,β‐ditosyloxy ketones via C−C bond formation from their corresponding chalcones in moderate to good yields (55–82 %). The ambiguity regarding the exact molecular structure of the α‐aryl‐β,β‐ditosyloxy ketones was examined through the single crystal X‐ray diffraction data. At last, the synthesis of isoflavones was carried out in moderate to good yields (50–80 %) by performing the reaction of α‐aryl‐β,β‐ditosyloxy ketones with sodium hydroxide in aqueous methanol.

Development of an efficient biocatalytic three-component reaction for synthesizing pyrrole derivatives

Multi-component reactions (MCRs) enable the development of efficient and atom-economic methods for synthesizing pyrrole derivatives. However, the current MCRs methods for synthesizing pyrrole derivatives in the enzymatic process have been unexploited. Herein, we developed a one-pot three-component enzymatic promiscuous catalytic system with green, efficient, and atom-economic to construct pyrrole derivatives. In this system, amines and 1,3-dicarbonyl compounds formed enamines with subsequent Michael addition with nitroolefins catalyzed by trypsin. A series of pyrrole derivatives were successfully obtained with moderate to good yield (up to 92 %). In addition, molecular simulations were conducted to gain insight into the source of differing tolerance of aromatic amides and fatty amines and the intrinsic effect of solvents in this system. This enzymatic catalytic one-pot three-component system has excellent functional tolerance, simple operation, and application potential for industrial production demonstrated by the gram scale experiment.

Selective Functionalization of White Phosphorus with Alkyl Bromides under Photocatalytic Conditions: A Chlorine-Free Protocol to Dialkyl and Trialkyl Phosphine Oxides.

A novel and efficient method for the direct selective alkylation of white phosphorus (P4) with alkyl bromides has been developed, utilizing 4DPAIPN as the photocatalyst and Hantzsch ester as the reductant. This method facilitates the synthesis of structurally diverse dialkyl phosphine oxides in good yields, offering a streamlined alternative to the traditional stepwise approach of chlorinating P4 with Cl2 and subsequently displacing the chlorine atom. Noteworthy features of this reaction include excellent product selectivity, remarkable functional group tolerance, and a broad substrate scope. Additionally, this method is effective for the synthesis of trialkyl phosphine oxides.

A Pd(II) Complex Exhibiting Tetradentate NHC‐Phosphine Ligand: On Route to Unconventional Phosphonium Ylide Derivatives

AbstractUnusual open‐chain tetradentate NHC‐phosphine pre‐ligand [Ph2PCH(Ph)ImCH2ImC(H)PhPPh2](BF4)2 was prepared in a good yield by metal‐mediated approach starting from Mn(I) complex [Cp(CO)2Mn(η2‐Ph2P=C(H)Ph)](BF4) and bis(imidazole) derivative ImCH2Im. Its reaction with Pd(OAc)2 afforded dicationic Pd(II) complex of bis(NHC)bis(phosphine) ligand adopting κ4PĈĈP coordination mode as a mixture of two diastereomers. The deprotonation of the C(H)Ph ligand bridge in the latter using KN(SiMe3)2 as base provided stable complex exhibiting unconventional phosphonium ylide moiety, whereas all attempts to detect the corresponding bis(ylide) derivative failed.