Pot Manner Research Articles

Synthesis of 1,4-oxathiins via [3+3] annulation of pyridinium 1,4-zwitterionic thiolates with iodonium ylides

A straightforward and valuable approach for the synthesis of 1,4-oxathiins has been developed via [3 ​+ ​3] annulation of pyridinium 1,4-zwitterionic thiolates with iodonium ylides. C–S and C–O bonds were formed in one pot manner in this transformation, which features with readily available substrates, excellent tolerance of functional groups and mild reaction conditions. It would be of great value for the construction of 1,4-oxathiins with biological and pharmacological activity.

I2/PPh3‐Mediated Cyclization of Enaminones with Sodium Sulfinates: A Protocol for the Synthesis of 3‐Thiolated Chromones

AbstractAn I2/PPh3‐mediated synthesis of 3‐thiolated chromones starting from 2‐hydroxyphenylenones and sodium sulfinates was reported. This method features one pot manner, metal‐free, easy performance, readily available starting materials and illustrating potential value for some biologically or pharmaceutically active compounds. In addition, a possible mechanism was proposed based on the control experiments.

One pot synthesis of 2‐substituted thiobenzoazoles containing α‐sulfenylated aromatic ketones under transition metal‐free conditions

AbstractAn efficient synthesis of 2‐substituted thiobenzoazoles in pot manner was reported. Thus, tetramethylthiuram disulfide (TMTD) reacted with 2‐aminothiophenol, 2‐aminophenol, or 1,2‐phenylenediamine to form 2‐mercaptobenzo heterocycles through cyclization, and the subsequent C‐S bonding with 2‐bromoacetophenones gave the desired 2‐substituted thiobenzoazoles containing α‐sulfenylated aromatic ketones smoothly. The method features transition metal‐free, simple operation, mild conditions, short reaction time, and good yields, showing potential synthetic value for the synthesis of a variety of biological or pharmaceutically active compounds.

Synthesis of New Polyheterocyclic Pyrrolo[3,4-b]pyridin-5-ones via an Ugi-Zhu/Cascade/Click Strategy.

A diversity-oriented synthesis (DOS) of two new polyheterocyclic compounds was performed via an Ugi-Zhu/cascade (N-acylation/aza Diels-Alder cycloaddition/decarboxylation/dehydration)/click strategy, both step-by-step to optimize all involved experimental stages, and in one pot manner to evaluate the scope and sustainability of this polyheterocyclic-focused synthetic strategy. In both ways, the yields were excellent, considering the high number of bonds formed with release of only one carbon dioxide and two molecules of water. The Ugi-Zhu reaction was carried out using the 4-formylbenzonitrile as orthogonal reagent, where the formyl group was first transformed into the pyrrolo[3,4-b]pyridin-5-one core, and then the remaining nitrile group was further converted into two different nitrogen-containing polyheterocycles, both via click-type cycloadditions. The first one used sodium azide to obtain the corresponding 5-substituted-1H-tetrazolyl-pyrrolo[3,4-b]pyridin-5-one, and the second one with dicyandiamide to synthesize the 2,4-diamino-1,3,5-triazine-pyrrolo[3,4-b]pyridin-5-one. Both synthesized compounds may be used for further in vitro and in silico studies because they contain more than two heterocyclic moieties of high interest in medicinal chemistry, as well as in optics due to their high π-conjugation.

Rhodium-Catalyzed [4 + 2] Cascade Annulation to Easy Access N-Substituted Indenoisoquinolinones.

An efficient approach for the synthesis of N-substituted indenoisoquinolinones via rhodium(III)-catalyzed C-H bond activation/subsequent [4 + 2] cyclization starting from easily available 2-phenyloxazolines and 2-diazo-1,3-indandiones has been developed. A series of indeno[1,2-c]isoquinolinones were obtained in up to 93% yield through C-H functionalization, followed by intramolecular annulation, elimination, and ring-opening in a "one pot manner" under mild reaction conditions. This protocol features excellent atom- and step-economy and provides a novel strategy for the synthesis of N-substituted indenoisoquinolinones and a chance to study their biological activities.

A Simple and Modified One Pot Conversion of Carboxylic Acid to Ketone

Background: Ketone is one of the important functional groups in synthetic chemistry. For this reason, organic chemists focused on the synthesis of ketone starting from various functionalities since nineties. One of the method deals with the conversion of carboxylic acids to ketones in a one pot manner. We have recently reported a one pot transformation of carboxylic acid to ketone using TsCl or MsCl as an activator of carboxylc acid. In our previous reports, two equivalents of organometallic reagent have been used which may not be useful in medicinal chemistry. In this report, we have developed an alternative process for the transformation where only one equivalent of organometallic reagent has been employed. Objective: In present scenario, we are interested to develop a process for the transformation of carboxylic acid to ketone using one equivalent of an organometallic reagent. Methods: A carboxylic acid reacted with tosyl chloride in the presence of a sodium hydride to form a mixed anhydride. Here, the acidic proton was removed from the reaction mixture as hydrogen gas. This mixed anhydride was then treated with one equivalent of an organomagnesium reagent at -30°C to obtain the desired ketone. Results: Following the optimum conditions, a few commercially available carboxylic acids were treated with TsCl, followed by the treatment of phenyl magnesium and methyl magnesium bromide to obtain phenyl and methyl ketones, respectively, in good to excellent yields. Conclusion: A simple and modified one pot method for the conversion of carboxylic acids to ketone has been reported. In this developed process, one equivalent of the organomagnesium reagent has been used to obtain the desired ketone under the optimized reaction conditions.

Triple-Consecutive Isocyanide Insertions with Aldehydes: Synthesis of 4-Cyanooxazoles.

An efficient TMSOTf-promoted selective triple consecutive insertions of tert-butyl isocyanide into aldehydes has been developed, affording pharmacological interesting 4-cyanooxazoles in high yields in a one pot manner. The given method encompasses a wide range of substrates with tert-butyl isocyanide serving as sources of critical "CN" and "C-N═C" moieties. The versatile transformations of the resulting 4-cyanooxazoles were demonstrated. The key reaction intermediates for plausible mechanisms were determined.

Acid catalyzed one-pot approach towards the synthesis of curcuminoid systems: unsymmetrical diarylidene cycloalkanones, exploration of their single crystals, optical and nonlinear optical properties.

In the present study crystalline unsymmetrical diarylidene ketone derivatives BNTP and BDBC have been prepared by two sequential acid catalyzed aldol condensation reactions in a one pot manner. The crystal structures of both compounds were confirmed by single crystal X-ray diffraction analysis which revealed the presence of H-bonding interactions of type C-H⋯O, along with weak C-H⋯π and weak π⋯π stacking interactions that are involved in the crystal stabilization of both organic compounds. Hirshfeld surface analysis is carried out for the broad investigation of the intermolecular interactions in both compounds. The quantum chemical investigation was performed on the optimized molecular geometries of BNTP and BDBC to calculate optical and nonlinear optical (NLO) properties. The density functional theory (DFT) study showed that the third-order NLO polarizabilities of compounds BNTP and BDBC are found to be 226.45 × 10-36 esu and 238.72 × 10-36 esu, respectively, which indicates noticeable good NLO response properties. Additionally, the BNTP and BDBC molecules also showed the HOMO-LUMO orbital gaps of 5.96 eV and 6.06 eV, respectively. Furthermore, the computation of UV-visible spectra of the titled compounds indicated a limited and/or no absorption above the 400 nm region, directing a good transparency and NLO property trade-off for both synthesized compounds that may play a significant contribution in the future for optoelectronic technologies.

N‐Iodosuccinimide (NIS) Promoted Synthesis of Unsymmetrical Disulfides Starting from Isothiocyanates Under Transition‐Metal‐Free Conditions

AbstractUnder transition‐metal‐free conditions, a series of unsymmetrical disulfides could be quickly and conveniently obtained by NIS (N‐Iodosuccinimide)‐promotion in one pot manner. This method features mild conditions, easy operation, short reaction time and wide substrate scopes. It's noteworthy that the desired products could be obtained in moderate to good yields from inexpensive and easily available starting materials, providing an alternative way to afford various unsymmetrical disulfides.

Exhaustive Syntheses of Deuterium-labelled Compounds

Deuterium (2H, D) is a stable isotope of hydrogen (1H). Deuterium-incorporated (labelled) compounds are widely utilized in various scientific fields such as mechanistic studies of organic reactions, elucidation of drug metabolism, application as tracers for microanalysis. Recently, development of heavy drugs and molecular imaging using techniques such as neutron scattering and Raman spectroscopy are spotlighted. We have developed various deuterium-incorporated compounds using D2O as an inexpensive deuterium source to construct novel functional materials. The use of platinum group metals on carbon as catalysts could result in the multi-deuteration of compounds in the mixed solvents of 2-propanol and D2O, and site-selectively deuterated compounds can be synthesized by organocatalytic methods. In this review, the latter deuteration methods using organocatalysts and their applications are summarized. Terminal alkynes smoothly underwent deuterium incorporation by using triethylamine as an organic base or a solid resin possessing the tertiary amine moiety in the same molecule to give mono-deuterated alkynes. These compounds were partially reduced over our prepared specific palladium catalyst under atmospheric D2 gas to produce tri-deuterated alkenes. Achiral or chiral di-deuterated β-nitro alcohols were also prepared by the organic-base-catalyzed deuteration of nitromethane, followed by nitroaldol reactions in a one pot manner. The mono-deuteration of aromatic aldehyde could be effectively catalyzed by N-heterocyclic carbene. Furthermore, the α-deuteration of aliphatic aldehydes using a basic resin catalyst and the subsequent Knoevenagel condensation with malononitrile could provide γ-deuterium-incorporated α,β-unsaturated nitrile derivatives. The deuterated compounds thus obtained can be important synthetic precursors to construct the deuterium-incorporated target functional materials.

One Pot Conversion of Carboxylic Acid to Ketone Using Trimethylsilyl Chloride

Background: Ketone is abundant in many natural products and in pharmaceuticals. It is believed to be one of the important functional groups in organic chemistry. Till date,several research approaches have been made to access ketone from a readily available starting materials. One such notable transformation consists of the conversion of carboxylic acid to the corresponding ketone in a one pot manner. Objective: We aimed to develop a simple one pot reaction for the conversion of carboxylic acid to ketone. This reaction could be useful to convert all types of carboxylic acid to ketone in a facile manner. Methods: In this procedure, a carboxylic acid has been converted to the corresponding trimethylsilyl ester using trimethylsilyl chloride in the presence of a base. A suitable organometallic reagent can interact with the ester formed at 20°C to produce the corresponding ketone. Results: Under the optimized reaction conditions, various aromatic, aliphatic and heteroaromatic carboxylic acids have been converted to the corresponding ketones using organolithium reagents, in a one pot manner. Moderate to good yields of the desired ketones were observed in most of the transformations. Conclusion: Conversion of carboxylic acid to ketone has been reported in a one pot fashion, where carboxylic acid has been transformed to its silyl ester. Organolithium reagents were used as nucleophile for our reaction purpose, whereas the organomagnesium reagents were not useful for this transformation. Aliphatic, aromatic and heteroaromatic carboxylic acids have been converted to the ketones following a simple process.

Template-free assembly of protonated g-C3N4 nanosheets into microspheres with enhanced UV-light photocatalytic activity

Microspheres composed of H2SO4-protonated graphitic carbon nitride (g-C3N4) nanosheets were prepared through a template-free dialysis method. The g-C3N4 microspheres displayed a much larger band gap and greater UV light absorption in the light region of 200–300 nm compared with that of bulk g-C3N4, and thus substantially improved their UV light photocatalytic performance towards the degradation of Rhodamine B (RhB). The present work approached soft solution assembly of g-C3N4 nanosheets in a one pot manner, demonstrating a new strategy for constructing g-C3N4 nanostructures.

Rhodium(III)‐Catalyzed Cross Coupling of Sulfoxonium Ylides and 1,3‐Diynes to Produce Naphthol‐Indole Derivatives: An Arene ortho C−H Activation/Annulation Cascade

AbstractSynthesis of naphthol‐indoles starting from easily available 1,3‐diynes and sulfoxonium ylides via RhIII‐catalyzed C−H activation/hydroamination cascade process in a one pot manner has been developed. The reaction proceeds through a RhIII‐catalyzed arene ortho C−H activation and silver‐catalyzed hydroamination cascade to afford a variety of C2 position functionalized indoles in good yields with broad substrate scope and good functional group tolerance.

Synthesis of indoline-fused eight-membered azaheterocycles through Zn-catalyzed dearomatization of indoles and subsequent base-promoted C-C activation.

A cascade reaction involving the Zn-catalyzed dearomatization of indoles, base-promoted ring-expansion and intramolecular SNAr reaction has been developed. This process realized a novel, atom economical and efficient synthesis of indoline-fused eight-membered azaheterocycles in a one pot manner.

Synthesis, Characterization and Cytotoxic Studies of New Thiazolidinones

A new series of substituted aromatic thiazolidinones [1-4]were synthesized by the reaction of acetophenone and its derivatives [5-8]with hydrazine hydrate and merceptoacetic acid in absolute ethanol in one pot manner. The striking feature of this reaction is the formation of hydrazone in situ which in turn undergoes the cyclization with mercepto acetic acid, leading to the formation of new thiazolidinones. Thus, the thiazolidinone ring closes at carbonyl carbon, by the attack of sulfur of mercaptoacetic acid moiety, preferentially from the front (I², axial) so that the nitrogen has an equatorial orientation (I±, equatorial) to avoid steric repulsion, giving minimum steric hindrance. The new compounds were characterized by spectral (IR, 1H NMR,13C NMR, MS) and analytical methods. The new compounds were screened for cytotoxicity (MTT assay) as well as genotoxicity (Comet assay) studies against different cancer cell lines, during which the new compounds depicted potential anticancer behaviour.

Design and synthesis of novel benzenesulfonamide containing 1,2,3-triazoles as potent human carbonic anhydrase isoforms I, II, IV and IX inhibitors

In a quest to discover new biologically active compounds, a series of twenty novel heterocyclic derivatives substituted at position 5 with -H (7a-7j) or -CF3 (8a-8j), bearing benzenesulfonamide at N-1 position and various aroyl groups at position 4 of the 1,2,3-triazole ring was synthesized and screened for their carbonic anhydrase (CA, EC 4.2.1.1) inhibition potential against four human (h) isoforms hCA I, II, IV and IX. All the compounds (7a-7j and 8a-8j) were synthesized via [3+2] cycloaddition reaction from 4-azidobenzenesulfonamide. Interestingly, compounds 7a-7j were prepared in one pot manner via enaminone intermediate using novel methodology. All the newly synthesized compounds (7a-7j &8a-8j) were found to be excellent inhibitors of edema related isoform hCA I with their inhibition constant (Ki) ranging from 30.1 to 86.8 nM as compared to standard drug acetazolamide (AAZ) with Ki = 250 nM. Further it was found that most of tested compounds were weaker inhibitors of isoform, hCA II although compounds 7b, 7d-7e, 8a, 8d-8f, 8i (mostly with electron withdrawing substituents) have shown better inhibition potential (Ki < 50 nM). Against glaucoma associated hCA IV, compound 7d was found to be better inhibitor (Ki = 52.4 nM) than AAZ (Ki = 74 nM) while against tumor associated hCA IX, all the compounds have shown moderate inhibition potential. Present study have added one more step in exploring the 1,2,3-triazlole moiety in the medicinal field.

Selective synthesis of 2-aminobenzoxazoles and 2-mercaptobenzoxazoles by using o-aminophenols as starting material

2-Aminobenzoxazoles and 2-mercaptobenzoxazoles were selectively synthesized by treating o-aminophenols with dithiocarbamates and tetramethylthiuram disulfide (TMTD), respectively. With the promotion of NaH/CuI, the reaction of o-aminophenols with dithiocarbamates gave 2-aminobenzoxazoles with good yield (70–92%) in one pot manner, and 2-mercaptobenzoxazoles were synthesized (yield: 55–80%) in the presence of K2CO3 by treating o-aminophenols with tetramethylthiuram disulfide (TMTD). The feature of this method includes good to excellent yield, easy performance and broad substrate scope, which makes the protocol practical and attractive in the preparation of some potential pharmaceutically active compounds.

Reaction of Ynamides with Iminoiodinane-Derived Nitrenes: Formation of Oxazolones and Polyfunctionalized Oxazolidinones.

This article describes the reaction of ynamides with metallanitrenes generated in the presence of an iodine(III) oxidant. N-(Boc)-Ynamides are converted to oxazolones via a cyclization reaction. The reaction is mediated by a catalytic dirhodium-bound nitrene species that first behaves as a Lewis acid. The oxazolones can be converted in a one pot manner to functionalized oxazolidinones following a regio- and stereoselective oxyamination reaction with the same nitrene reagent generated in stoichiometric amounts.

Brønsted acid-mediated cyclization-dehydrosulfonylation/reduction sequences: An easy access to pyrazinoisoquinolines and pyridopyrazines.

An efficient and alternative synthetic approach has been developed to prepare various N-(arylethyl)piperazine-2,6-diones from 4-benzenesulfonyliminodiacetic acid and primary amines using carbonyldiimidazole in the presence of a catalytic amount of DMAP at ambient temperature. Piperazine-2,6-diones are successfully transformed to pharmaceutically useful pyridopyrazines or pyrazinoisoquinolines and ene-diamides via an imide carbonyl group activation strategy using a Brønsted acid. Subsequent dehydrosulfonylation reactions of the ene-diamides, in a one pot manner, smoothly transformed them to substituted pyrazinones. A concise synthesis of praziquantel (1) has also been achieved through this method.

Efficient construction of C-N and C-S bonds in 2-iminothiazoles via cascade reaction of enaminones with potassium thiocyanate.

A novel and highly efficient protocol has been developed for the regioselective synthesis of 2-iminothiazole derivatives with potential biochemical interest by the reaction of enaminones, potassium thiocyanate (KSCN), and N-bromo succinimide (NBS) under mild conditions. The reaction proceeds via the formation of α-bromo enaminones as a versatile intermediate followed by thiocyanation/intramolecular cyclization in a one pot manner. The developed method is particularly attractive due to various advantages including operational simplicity, mild conditions, being catalyst free, and high bond-forming efficiency. The proposed protocol explores the synthetic routes of thiazoles by using various functional enaminones.