Ved Verma | Banasthali University (original) (raw)

Papers by Ved Verma

Chemistry of Heterocyclic Compounds, 2018

Лaтвийcкий инcтитут opгaничecкoгo cинтeзa Recently, metal-mediated cross-coupling reactions of su... more Лaтвийcкий инcтитут opгaничecкoгo cинтeзa Recently, metal-mediated cross-coupling reactions of sulfur electrophiles have shown highly effective and practical approaches for the formation of carbon-carbon bonds. Desulfitative cross-coupling reactions of sulfur electrophiles, such as thiols, sulfoxides, thioethers, thioesters, aryl sulfones, and sulfoximines, have number of advances as they are often less expensive and more reactive than corresponding aryl chlorides. Generally, these sulfur electrophiles are involved in Suzuki-Miyaura, Negishi, Stille, Sonogashira-Hagihara, Mizoroki-Heck type of crosscoupling reaction. 1-15 Buchwald and Hartwig exploited the transition metalcatalyzed direct amination reactions of aryl halides and provides most powerful methods for the synthesis of arylamines. Since then the coupling of ammonia through metal-amido complex for the synthesis of primary arylamines has undergone significant advancement. 16-21 However, to date, amination reactions involving organosulfur as electrophile are relatively rare. Therefore, we envisaged that desulfitative cross coupling perhaps can provide a novel and attractive approach for the direct amination of heteroaryl thiols. 2-Aminopyrimidine is a common core motif in variety of natural products and pharmaceuticals and displays a wide range of biological properties. Several natural products and drugs such as variolin B, meridianin A, and annomontine, containing 2-aminopyrimidine scaffolds, and also abacavir, used for the treatment of HIV infections and AIDS, 22-31 (Fig. 1) raised our interest toward the desulfitative synthesis of amino-functionalized heterocycles. Herein we

ACS Omega

A mechanistic approach to understand the course of metabolism for synthetic 1,2,4-trioxanes, pote... more A mechanistic approach to understand the course of metabolism for synthetic 1,2,4-trioxanes, potent antimalarial compounds, to evaluate their bioavailability for antimalarial action has been studied in the present work. It is an important parameter to study the course of metabolism of a drug candidate molecule when administered via oral route during its journey from oral intake to its target site. From the pharmacokinetics point of view, it determines the bioavailability of an active drug or a prodrug at the target point. In this work, synthetic arylvinyl-1,2,4-trioxanes 1a−u have been evaluated under various acidic conditions to mimic the milieu of the stomach (pH between 1.5 and 3.5) through which they have to pass when administered orally. The effect of acid on trioxanes led to their degradation into corresponding ketones and glyoxal. Under such acidic conditions glyoxal polymerized to form a nonisolable condensate product. The study indicates that the actual bioavailability of the drug is far less than the administered dose.

Heterogeneous Catalysis in Organic Transformations, 2022

Current Organocatalysis, 2021

Background: Coumarin and its derivatives have attracted the attention of synthetic chemists due t... more Background: Coumarin and its derivatives have attracted the attention of synthetic chemists due to their importance in pharmaceutical and medicinal chemistry. The acid-catalyzed cyclization route constitutes the method of choice to access these important compounds. Objective: In this paper, we have discussed the synthesis of 4-aryldihydrocoumarins via a one-pot p-sulfonic acid calix[4]arene catalyzed reaction. Methods: The easily prepared calix[4]arene derivative catalyzes a sequential reaction involving Michael addition followed by intramolecular lactonization to afford the title compound in effective yield. Results: The described methodology is devoid of any metal salt, thus making it a very appealing protocol to safely produce dihydrocoumarins of pharmacological importance. Conclusion: The easy recovery, non-toxicity, and reusability of the catalytic system are some of the other advantages of our procedure. In addition, the catalyst efficiency is not compromised after its success...

ChemPlusChem, 2020

The concept of gene vectors for therapeutic applications have been known for several years, but i... more The concept of gene vectors for therapeutic applications have been known for several years, but it is far from revealing its actual potential. With the advent of hollow cylindrical carbon nanomaterials such as carbon nanotubes (CNTs), researchers have invented several new tools to deliver genes at the required site of action in mammalian and plant cells. The ease of diversified functionalization has allowed CNTs to be by far the most adaptable non-viral vector for Gene Therapy. This minireview addresses the dexterity with which CNTs undergo surface modifications and their applications as a potent vector in gene therapy of humans and plants. Specifically, we will discuss the new tools that scientific communities have invented to achieve gene therapy using plasmid DNA, RNA silencing, suicide gene therapy, and plant genetic engineering. Additionally, we will shed some light on the mechanism of gene transportation using carbon nanotubes in cancer cells and plants.

Angewandte Chemie, 2019

Aims: Studies have shown that the fourth harmonic of the radial pulse wave (C4) is associated wit... more Aims: Studies have shown that the fourth harmonic of the radial pulse wave (C4) is associated with atherosclerotic processes and myocardial ischemia. We sought to investigate whether C4 is an independent predictor of adverse cardiac events (ACE). Methods: The baseline C4 is calculated using the Fourier series method. 1968 asymptomatic patients with type 2 diabetes were followed up for 1.8 ± 0.4 years and survival analysis were performed using Cox proportional hazard model. Results: The Cox regression analysis showed that the C4 value is independent and inversely related to ACE both before and after adjusting for age, sex, smoke, systolic blood pressure, dyslipidemia, and Hba1c. (P for trend b 0.001) Conclusions: Decreasing C4 is associated with an increased risk of ACE in asymptomatic patients with type 2 diabetes.

European Journal of Organic Chemistry, 2011

A highly efficient TMSOTf-catalyzed HMDS silylation of sugars, which can easily be integrated wit... more A highly efficient TMSOTf-catalyzed HMDS silylation of sugars, which can easily be integrated with subsequent reactions in one-pot fashion, has been developed. Its usefulness was demonstrated by applications to streamlined regioselective one-pot protection and nonenzymatic acetylation of un

Journal of Organometallic Chemistry, 2021

Abstract Silver(I) ferrocenyl dithiophosphonato [Ag{S2P(OiPr)Fc}]n I, [Fc = Fe(n5-C5H4)(n5-C5H4)]... more Abstract Silver(I) ferrocenyl dithiophosphonato [Ag{S2P(OiPr)Fc}]n I, [Fc = Fe(n5-C5H4)(n5-C5H4)] 1D polymer was yielded via a ligand exchange reaction between silver nanocluster [Ag21(S2P(OiPr2)12)]PF6 and monoanionic [S2P(OiPr)Fc]¯ ligand. As per molecular stoichiometry of 1, a direct reaction between [Ag(CH3CN)4]PF6 and [S2P(OiPr)Fc]− was performed in methanol solvent and surprisingly, generate a tetrahedral Ag4{S2P(OiPr)Fc}4 2 cluster instead of 1. Both (1 and 2) clusters are the novel example of homoleptic Ag(I) complexes supported by ferrocenyl dithiophosphonates. Molecular structure of these clusters was unequivocally established by single crystal X-ray crystallographic analyses and supported by the ESI-MS, and 1H and 31P NMR spectroscopy. Structural elucidations reveal that compound 1 has subsequently Ag2S2 square plane and Ag2S4P2 twisted boat units to build a long chain 1D polymer. The cluster 2 exhibits with a tetrahedral Ag(I) core framed by four [S2P(OiPr)Fc]− ligands. interstingly, the [S2P(OiPr)Fc]− ligand display a trimetallic triconnective (η3; µ1, µ2) bonding pattern in both molecules. The electrochemical behaviours of both compounds (1 and 2) were studied by using cyclic voltammetry, which shows a single wave for all the peripheral ferrocenes and implies negligible electrostatic factor between all ferrocene moieties.

Organic & Biomolecular Chemistry, 2018

A novel and efficient protocol concerning palladium catalyzed the three-component reaction of 2-a... more A novel and efficient protocol concerning palladium catalyzed the three-component reaction of 2-azidobenzaldehyde, isocyanide, and hydroxylamine hydrochloride is developed. The method allows the rapid elaboration of quinazoline 3-oxides in a...

Chem. Commun., 2015

Homogeneous N-functionalisation of amino sugars can be achieved via efficient CH3CN-promoted hexa... more Homogeneous N-functionalisation of amino sugars can be achieved via efficient CH3CN-promoted hexamethyldisilazane per-O-trimethylsilylation.

Chemistry - A European Journal, 2012

Dedicated to Professor Chin-Hsing Chou on the occasion of his 65th birthday The presence of 2-deo... more Dedicated to Professor Chin-Hsing Chou on the occasion of his 65th birthday The presence of 2-deoxy-or 2,6-dideoxyglycosides, either as a single structural element or as the components of oligosaccharides in either a or b linkages, is essential to the activity of many natural products, especially for antibiotics and anticancer agents. [1] However, the stereoselective 2-deoxyglycosylation reaction remains a long-standing challenge in carbohydrate chemistry. Owing to the lack of C2 functionality, which governs the stereoselectivity of the reaction and stabilizes the intermediary oxonium ion, glycosylation reactions that involve these glycosides are usually held back by poor stereoselectivity and the high susceptibility of 2-deoxyglycosides to acid hydrolysis. [2, 3] Although numerous strategies and conditions, including the use of glycal precursors, [4] have been developed [3] and the anomeric effect leads to the preferential formation of a-anomers, moderate yields and poor stereoselectivities are usually encountered in the synthesis of 2-deoxyglucosides. To control the stereoselectivity of this reaction, indirect methods that introduce iodine, [5] bromine, [6] or fluorine atoms, [7] as well as thio [8] or seleno [9] groups at the C2 position, are typically adopted. The 1,2-migration-glycosylation of thioglycosides [10] and the reduction of the C2 oxygen [11] or nitrogen [12] moieties also provide alternatives. These indirect approaches are reliable but need additional synthetic steps to remove these stereo-governing groups. Direct methods, without the need for modifying the C2 functionality, are more concise but usually lead to anomeric mixtures. [3] The O-glycosylation of serine and threonine is an omnipresent post-translational modification of proteins and peptides. Studies have shown that even the decoration of a peptide with a single N-acetylglucosamine or N-acetylgalactos-A C H T U N G T R E N N U N G amine group can alter its secondary structure, in which the 2-acetamido moiety is believed to play a decisive role. [13] To further confirm this structure-activity relationship, we wanted to synthesize O-glycopeptides 1 and 2, which were decorated with 2-deoxy-glucoside. Therefore, easy access to a-or b-2-deoxyglucosyl-l-serine (3) and-threonine (4) is critical (Figure 1).

Tetrahedron Letters, 2021

Abstract An efficient and highly diastereoselective synthesis of schizocommunin analogues has bee... more Abstract An efficient and highly diastereoselective synthesis of schizocommunin analogues has been achieved through an iron-catalyzed C(sp3)-H/C(sp3)-H cross-dehydrogenative coupling reaction between 2-methyl quinazolinones and indolin-2-ones. This method requires air (molecular oxygen) as an oxidant instead of chemical equivalent oxidising agents and prefunctionalized coupling partners. The developed schizocommunin analogues were obtained in good to excellent yields and various kinds of functional groups were tolerated. It is worthy to note that schizocommunin, a bioactive natural product displaying broad spectrum of biological properties in which anticancer property is one of them.

Organic & Biomolecular Chemistry, 2021

A convenient electrochemical synthetic method for S-thiocarbamates has been developed under batch... more A convenient electrochemical synthetic method for S-thiocarbamates has been developed under batch and continuous flow conditions.

New Journal of Chemistry, 2018

Two rationally designed β-carboline–imidazopyridine hybrid chromofluorescent sensors S1 and S2 ha... more Two rationally designed β-carboline–imidazopyridine hybrid chromofluorescent sensors S1 and S2 have been successfully synthesized and evaluated for the selective sensing of metal ions and anions.

Organic Letters, 2019

A metal-free diastereo-/regioselective modular synthetic approach for the synthesis of highly con... more A metal-free diastereo-/regioselective modular synthetic approach for the synthesis of highly constrained tetrahydroquinoline-fused tetracyclic heterocycles from easily available substrates has been developed. This two-step strategy utilizes an Ugi four-component reaction, followed by the intramolecular spirocarbocyclization and iodination reactions in a single operation. The transformation is mild and operationally simple, which provides architecturally complex polycyclic heterocycles with high diastereoselectivity. Furthermore, the preliminary cytotoxicity screening of selected compounds displayed promising anticancer activity against human cancer cell lines.

Tetrahedron, 2019

Abstract A divergent regioselective palladium (II) catalyzed approach through post Ugi cyclizatio... more Abstract A divergent regioselective palladium (II) catalyzed approach through post Ugi cyclization is described. The Ugi adduct underwent intramolecular ortho-hydroarylation via 6-endo-dig cyclization for the direct access to 4-aryl-2-quinolones. Incorporation of iodine at the C-3 position of 2-quinolone followed by Suzuki-Miyaura coupling results into the more diversified 3,4-diaryl-2-quinolones.