Excellent Yields Research Articles

Egg shell powder mediated Cu catalyst: A biowaste based catalytic approach for the synthesis of quinazolin-4(3H)-ones and propargyl amines

A novel and efficient approach for a tandem oxidative synthesis of quinazolin-4(3H)-one from 2-aminobenzonitrile and benzyl alcohol has been unveiled via Cu2(CO3)(OH)2. Herein CuSO4.5H2O accompanied by egg shell powder is used for the easy preparation of Cu2(CO3)(OH)2. The reported method portrays a wide range of substrate scope with good to excellent yield and the given reaction proceed at room temperature within 12 h. Single crystal of one of the synthesized quinazolin-4(3H)-ones was analysed through single crystal X-ray diffraction (SC-XRD). Some of the compounds reported here are also known to possess various pharmaceutical activities. Eventually the newly prepared catalyst was applied for propargylamine synthesis via a multi component reaction. Perceiving all the advantages, present protocol is conceivably considered as clean, cost-effective and sustainable over reported procedures used for synthesis of quinazolin-4(3H)-ones and propargyl amines.

Anilines Formation via Molybdenum-Catalyzed Intermolecular Reaction of Ynones with Allylic Amines.

The multi-substituted anilines are widely found in organic synthesis, medicinal chemistry and material science. The quest for robust and efficient methods to construct a diverse array of these compounds using readily accessible starting materials under simple reaction conditions is of utmost importance. Here, we report an unprecedented and efficient approach for the synthesis of 2,4-di and 2,4,6-trisubstituted anilines. With a simple molybdenum(VI) catalyst, a wide range of 2,4-di and 2,4,6-trisubstituted anilines were efficiently prepared in generally good to excellent yields from readily accessible ynones and allylic amines. The synthetic potential of this methodology was further underscored by its applications in several synthetic transformations, gram-scale reactions, and derivatization of bioactive molecules. Preliminary mechanistic studies suggested that this aniline formation might involve a cascade of aza-Michael addition, [1, 6]-proton shift, cyclization, dehydration, 6π-electrocyclization, and aromatization. This novel strategy provided a robust, simple, and modular approach for the syntheses of various valuable di- or trisubstituted anilines, some of which were otherwise challenging to access.

Anilines Formation via Molybdenum‐Catalyzed Intermolecular Reaction of Ynones with Allylic Amines

The multi‐substituted anilines are widely found in organic synthesis, medicinal chemistry and material science. The quest for robust and efficient methods to construct a diverse array of these compounds using readily accessible starting materials under simple reaction conditions is of utmost importance. Here, we report an unprecedented and efficient approach for the synthesis of 2,4‐di and 2,4,6‐trisubstituted anilines. With a simple molybdenum(VI) catalyst, a wide range of 2,4‐di and 2,4,6‐trisubstituted anilines were efficiently prepared in generally good to excellent yields from readily accessible ynones and allylic amines. The synthetic potential of this methodology was further underscored by its applications in several synthetic transformations, gram‐scale reactions, and derivatization of bioactive molecules. Preliminary mechanistic studies suggested that this aniline formation might involve a cascade of aza‐Michael addition, [1, 6]‐proton shift, cyclization, dehydration, 6π‐electrocyclization, and aromatization. This novel strategy provided a robust, simple, and modular approach for the syntheses of various valuable di‐ or trisubstituted anilines, some of which were otherwise challenging to access.

One-Pot Stereoselective Synthesis of the Naphthofurano-Iminosugars via a [3 + 2] Cycloaddition Reaction.

This study presents the synthesis of novel naphthofurano-iminosugars (4) using 2,3-O-isopropylidene D-ribose tosylate (1a), anilines (2), and 1,4-benzoquinone (3a) as starting materials through key iminium ion/enamine intermediates via [3 + 2] cyclization reactions at room temperature. The reaction has unique regioselectivity and stereoselectivity with moderate to excellent yields. The adaptability of this method has been demonstrated using various substituted anilines, on which both electron-donating and electron-withdrawing groups were well employed in the reactions. Notably, the treatment of the fused multicyclic iminosugar 4 with TFA efficiently leads to an interesting unexpected pyridinium salt (8), possible via four sequential steps: deprotection of the 2,3-O-isopropylidene group, furan ring opening, dehydration condensation of the OH groups, and elimination of water.

Ir-Catalyzed Leuckart-Type Reductive Amination of Carbonyls

Formamides are fundamental motifs prevalent in drugs, pesticides, dyes, fragrances. Herein, we described an Ir-catalyzed Leuckart-type reductive amination of carbonyls, delivering formamides in moderate to excellent yields. In this process, the ammonium formate was used as N-formylated reagent to produce the formamide products. This protocol provides a new procedure for formamide synthesis.

Phosphine-Mediated Reductive Insertion of α-Keto Esters and Isatins into Phthalic Anhydride Derivatives.

Herein, we report an unprecedented P(NMe2)3-mediated reductive insertion of 1,2-dicarbonyl compounds including α-keto esters and isatins into phthalic anhydride-derived alkenes and phthalic anhydrides, which furnishes the corresponding isochroman-1-ones and isochroman-1,4-diones, respectively, in moderate to excellent yields with high chemo- and regioselectivity. Furthermore, the asymmetric version of the ring expansion reaction could be realized by using a chiral auxiliary strategy. Mechanistically, the nucleophilic attack of the Kukhtin-Ramirez adduct, generated from P(NMe2)3 and 1,2-dicarbonyl compound, to the anhydride derivative, followed by a cascade ring-opening and ring-closure process, affords the ring expansion product. The reaction represents a novel metal-free carbon insertion ring expansion of aliphatic rings and also the first [1 + 5] annulation involving the Kukhtin-Ramirez adducts.

Rhodium-Catalyzed Pyridylation of Alkynamides with Pyridylboronic Acids: A Route to Functionalized Enamides.

The catalytic direct hydroarylation of alkynamides is a highly efficient approach for accessing functionalized trisubstituted arylalkenes with amide groups. Herein, we report a rhodium-catalyzed pyridylation of alkynamides with pyridylboronic acids, yielding diverse primary, secondary, and tertiary enamides in good to excellent yields (up to 94%). This reaction demonstrates broad tolerance towards various alkyl and aryl functional groups, providing convenient access to a diverse array of alkenylpyridine derivatives. To demonstrate potential applications in late-stage hydropyridylation, we synthesized α,β-unsaturated ketones, aldehydes, and esters with high yields from the pyridylation product of Weinreb amides. This indirect expansion of the substrate scope enhances the practicality of this strategy. Additionally, the α,β-unsaturated ketone obtained can be further reduced to yield a chiral alcohol with a 99% ee, further demonstrating the versatility and potential utility of this approach.

Efficient generation of novel phosphorus ylides via chemoselective and chemospecific reactions utilizing 2-(arylamino)-2-thioxoacetamide and methyl benzoylglycinates as precursors with activated acetylenic compounds

A chemospecific and chemoselective procedure has been developed for the efficient synthesis of novel phosphorus compounds, achieving moderate to excellent yields. This method involves the reaction of 2-(arylamino)-2-thioxoacetamide and methyl benzoylglycinate precursors with PPh3 in the presence of activated acetylenic esters. Notably, the reaction exhibits superior selectivity toward the NH2 group in 2-(arylamino)-2-thioxoacetamide, rather than the NH group. Moreover, when methyl benzoylglycinates are employed as a precursor, the reaction yields two distinct families of ylides, each with its own unique percentage yield.

NiCo2O4-Nanoparticle-Catalyzed Microwave-Assisted Dehydrogenative Direct Oxidation of Primary Alcohols to Carboxylic Acids under Oxidant-Free Conditions

AbstractHere, we report the NiCo2O4-nanoparticle-catalyzed dehydrogenative direct oxidation of primary alcohols to carboxylic acid in the presence of KOH under microwave irradiation in the absence of any oxidant in good to excellent yields (75–99%) within a short reaction time (5–10 min). The polycrystalline cubic spinel phase of NiCo2O4 nanoparticles (NPs) with an average size of 25 nm were synthesized by the co-precipitation method and analyzed properly by using powder X-ray diffraction, field emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, and transmission electron microscopy measurements. The NiCo2O4 NPs were stable under the reaction conditions and reused for up to eight cycles without appreciable loss in the yield of benzoic acid. According to mechanistic insight, the KOH acts as a second oxygen source and is essential for the synthesis of carboxylic acid from alcohols. The hydrogen gas was found to be the only byproduct of this method detected by chemical reactions.

Iron-Catalyzed Chemoselective Transfer Hydrogenation of α,β-Unsaturated Ketones Using H2O as a Surrogate of Hydrogen.

Sustainable and highly economical iron-catalyzed chemoselective reduction of C═C of α,β-unsaturated ketones has been established under mild reaction protocols. Water is used as a green and abundant surrogate of hydrogen and is scarcely used in organic synthetic transformations as a source of hydrogen. The developed protocol offers a broad spectrum for chemoselective transfer hydrogenation of α,β-unsaturated ketones. Moreover, the method was found to be highly effective for aryl and ferrocenyl α,β-unsaturated ketones consisting of one or two double bonds and with multiple functionalities. Moreover, the present method avoids prolonged reaction time, provides a wide range of substrates with excellent yield, and circumvents the tedious chromatographic workup.

Synthesis of Highly Substituted Oxaboroles from Oxaboranes via a Selective Petasis Borono-Mannich Reaction.

We present a novel and efficient method for the synthesis of highly substituted non-benzofused oxaboroles. Reactions of oxaboranes, morpholine, and salicylaldehyde in toluene heated to 85 °C for 4 h produce the corresponding oxaborole products in yields up to 93%. The process is effective across a diverse substrate scope and can be scaled to produce gram quantities of densely functionalized oxaboroles in excellent yield. Exclusive aryl transfer over vinyl transfer is observed. Computational insights further elucidate the inherent selectivity of this process.

Photoinduced Palladium-Catalyzed Radical Germylative Arylation of Alkenes with Chlorogermanes.

We describe a visible light-induced palladium-catalyzed radical germylative arylation of alkenes with easily accessible chlorogermanes. This protocol provides expedient access to germanium-substituted indolin-2-ones in good to excellent yields under mild reaction conditions. The key step for this strategy lies in the reductive activation of germanium-chloride bonds with an excited palladium complex under visible light irradiation. The involvement of germanium radicals was evidenced by electron paramagnetic resonance spectroscopy experiments.

Domino Approach to Heterocycles-Based Unsymmetrical Triarylmethanes through Heteroannulation of 2-(2-Enynyl)-pyridines with Enaminones.

Herein, we report a copper-catalyzed protocol to access unsymmetrical triarylmethanes containing both indolizine and the chromone scaffolds in the same molecule via a 5-endo-dig cyclization of 2-(2-enynyl)-pyridines followed by reaction with 2-hydroxyaryl enaminones. A variety of 2-hydroxyaryl enaminones and 2-(2-enynyl)-pyridines were subjected to reaction under the optimal reaction conditions, and the respective triarylmethanes were obtained in good to excellent yields.

Intermolecular Regioselective Alkylarylation of Vinylarenes via Photoredox/Nickel Dual Catalysis.

A novel photoredox/nickel dual catalytic intermolecular alkylarylation of vinylarenes with tertiary and secondary alkyltrifluoroborates and aryl bromides is described, which affords 1,1-diarylalkane frameworks that are found in various natural products as well as functionalized molecules in good to excellent yield and regioselectivity through a radical relay process. Notably, this redox-neutral reaction could proceed efficiently with good tolerance of various substrates, including a great diversity of commercially available (hetero)aryl bromides, alkyltrifluoroborates, and vinylarenes.

Divergent Reaction of Alkynes and TsCN: Synthesis of β-Sulfinyl Alkenylsulfones and (E)-Vinyl Sulfones.

An efficient and high-selectivity approach for the divergent synthesis of β-sulfinyl alkenylsulfones and (E)-vinyl sulfones from alkynes and TsCN is described. A series of disulfurized products were constructed under mild conditions in the absence of transition metals. This transformation featured excellent regio- and stereoselectivity, good functional group compatibility, and broad substrate scope. The copper(I)-catalyzed sulfonation of alkynes with TsCN that affords (E)-vinyl sulfones in good to excellent yields was also developed.

Oxone-Mediated Regioselective Oxy-iodination of 1-Aryl/Alkyl Butadienes Using TBAI.

A simple, mild, and environmentally benign regioselective oxy-iodination of 1-aryl/alkyl butadienes has been developed. While styrenes have been explored previously, this work on dienes has been highly regioselective and metal-free in oxy-iodination following Markovnikov's rule. The oxy-iodination products were obtained in good to excellent yields using various co-solvents (H2O, MeOH, EtOH, AcOH, etc.). In addition, the halohydrins have been useful building blocks in the synthesis of various functionalized keto iodides and azido alcohols.

Electro- and Mechanochemical Strategy as a Dual Synthetic Approach for Biologically Relevant 3-Nitro-imidazo-[1,2-a]pyridines.

We herein disclose a dual synthetic approach involving electrochemical and mechanochemical strategies for diversely functionalized 3-nitro-2-aryl-immidazo[1,2-a]pyridines. Both methods offer a practical and straightforward alternative route for accessing this important class of biologically promising nitrogen-containing heterocycles. Significant advantages of the newly developed methods include mild and energy-efficient reaction conditions, avoidance of transition metal catalysts, external heating and additional oxidants, shorter reaction times, good to excellent yields, broad substrate scope, gram-scale applicability, operational simplicity, and eco-friendliness. Furthermore, a synthetic application was extended by successfully reducing synthesized 3-nitro-2-aryl-immidazo[1,2-a]pyridines to their corresponding amino derivatives.

Rapid Access to Triarylmethanes (TRAMs) Enabled by Direct Electrolysis of Indolizines with Carbonyls.

A fast, scalable, transition metal-free, electrochemical sp2 geminal functionalization of carbonyls enabled by anodic oxidation of non-prefunctionalized chromone-fused indolizines to access the triarylmethanes (TRAMs) is disclosed for the first time. This momentary electrochemical approach features the use of readily available carbonyls, implantation of the C(sp3) center (well-known for dramatically improving biological active potency), a broad substrate scope, and excellent yields of TRAMs with fluorescence properties.

Preparation, in vitro and in silico antioxidant and antibacterial studies of 4-aminoacetanilide azo derivatives

A new series of new 4-aminoacetanilide azo derivatives 1–13 were successfully synthesised via a diazo coupling reaction and gave a good to excellent yield of 73 %–93 %. The antioxidant capabilities of the series 1–13 screened through 2,2′-diphenyl-1-picrylhydrazyl (DPPH) assay and ferric reducing antioxidant power (FRAP) assay showed promising data of 12.6–199.4 ppm and 12.65–210.9 mg/ml Trolox equivalent, respectively. The findings supported by in silico docking analysis targeted Heme oxygenase-1 (HO-1) evidenced by a binding score of – 7.2 to – 8.2 kcal/mol outperforming the standard, ascorbic acid scoring only – 5.7 kcal/mol. Among all, compound 11 displayed the highest antioxidant potential with IC25 of 12.6 ppm against DPPH assay and 210.9 mg/ml Trolox for FRAP assay believed owing to the presence of methoxy group at ortho position in the phenolic compound that effectively lowered the ionisation potential and high up energy of highest occupied molecular orbital (HOMO). Nevertheless, the antibacterial potential of the series screened through the Kirby-Bauer disc diffusion method against Escherichia coli and Staphylococcus aureus showed no antibacterial activity postulated due to the presence of amide and acetyl group restricted the ability of the compound to form an interaction with the protein receptor of bacteria tested. This study provided new insight into the development of dual-functional drugs for non-communicable diseases and antimicrobial resistance.

Anti-selective Cyclopropanation of Nonconjugated Alkenes with Diverse Pronucleophiles via Directed Nucleopalladation.

A facile approach to obtaining densely functionalized cyclopropanes is described. The reaction proceeds under mild conditions via the directed nucleopalladation of nonconjugated alkenes with readily available pronucleophiles and gives excellent yields and good anti-selectivity using I2 and TBHP as oxidants. Pronucleophiles bearing a diverse collection of electron-withdrawing groups, including -CN, -CO2R, -COR, -SO2Ph, -CONHR, and -NO2, are well tolerated. Internal alkenes, which are generally challenging substrates in other cyclopropanation methods, provide excellent yields and good diastereoselectivity in this methodology, allowing for controlled access to cyclopropanes substituted at all three C atoms. DFT calculations and mechanistic experiments reveal that the major mechanistic pathway involves the initial α-iodination of the nucleophile, followed by anti-carbopalladation and intramolecular C(sp3)-I oxidative addition. Strain-release-promoted C(sp3)-C(sp3) reductive elimination then furnishes the cyclopropanated product.