Publications by authors named "Sridhar Balasubramanian"

140 Publications

Copper(I)-Catalyzed Formation of Isoquinoline and Quinoline Substituted Isobenzofurans.

Org Lett 2022 04 11;24(15):2899-2904. Epub 2022 Apr 11.

Fluoro and Agrochemicals Division, CSIR-Indian Institute of Chemical Technology, Hyderabad 500007, India.

An efficient synthetic organic transformation was developed to access isoquinoline-substituted isobenzofurans by reaction of substituted 1,5-diynes with isoquinoline -oxides. Moderate to excellent yields of isoquinoline-derived isobenzofurans were achieved by formation of a new C-C and two C-O bonds in the presence of copper catalyst in one pot. whereas quinoline-substituted isobenzofurans were obtained when the reaction was conducted using quinoline -oxides and 1,5-diynes in the presence copper catalyst.
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http://dx.doi.org/10.1021/acs.orglett.2c00864DOI Listing
April 2022

Cationic Gold-Catalyzed Intramolecular Cyclization of Substituted 1,5-Diynes to Access Indenone Derivatives.

Chem Asian J 2022 Apr 19;17(8):e202101408. Epub 2022 Mar 19.

Centre for X-ray Crystallography, CSIR-Indian Institute of Chemical Technology, Hyderabad, 500007, India.

An efficient intramolecular cyclization reaction was developed to achieve indenone derivatives. The substituted 1,5-diyenes were converted to the corresponding indenones via a gold-catalyzed organic transformation, and moderate to excellent yields of the title molecules were obtained via formation of two C=O and one C-C bonds under mild reaction conditions in one pot.
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http://dx.doi.org/10.1002/asia.202101408DOI Listing
April 2022

Unexpected ring opening of pyrazolines with activated alkynes: synthesis of 1-pyrazole-4,5-dicarboxylates and chromenopyrazolecarboxylates.

Org Biomol Chem 2022 01 5;20(2):334-338. Epub 2022 Jan 5.

Department of Organic Synthesis & Process Chemistry, CSIR-Indian Institute of Chemical Technology, Hyderabad-500 007, India.

1-Pyrazole-4,5-dicarboxylates and chromenopyrazole carboxylates were prepared by reacting pyrazolines with activated alkynes under neat conditions without a catalyst. The products were formed unexpected ring opening of pyrazolines with the elimination of styrene/ethylene. These types of transformations are unknown and the products formed were confirmed using their spectral/analytical data. In addition, the structures of compounds 5e and 5n were confirmed by single-crystal X-ray analysis. Control experiments were conducted to support the proposed reaction mechanism.
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http://dx.doi.org/10.1039/d1ob01727fDOI Listing
January 2022

Gold (I)-Promoted Intermolecular Cascade Annulation to Access 2-Hydroxybenzocarbazoles via a Meyer-Schuster Rearrangement.

Chem Asian J 2022 Feb 28;17(3):e202101269. Epub 2021 Dec 28.

Fluoro and Agrochemicals Department, CSIR-Indian Institute of Chemical Technology, 500007, Hyderabad, India.

An efficient cascade annulation protocol was established to access substituted 2-hydroxybenzocarbazoles from alkynylcyclohexadienones and substituted 2-aminophenols under gold catalysis. In this transformation a new C-C, two C-N bonds were formed sequentially and moderate to excellent yields of 2-hydroxybenzocarbazole derivatives were obtained selectively via Meyer-Schuster rearrangement in one-pot.
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http://dx.doi.org/10.1002/asia.202101269DOI Listing
February 2022

Catalyst- and Additive-Free Approach to Constructing Benzo-oxazine, Benzo-oxazepine, and Benzo-oxazocine: O Atom Transfer and C═O, C-N, and C-O Bond Formation at Room Temperature.

Org Lett 2021 Nov 13;23(21):8189-8193. Epub 2021 Oct 13.

Centre for Nano and Material Sciences, Jain University, Jain Global Campus, Bangalore, Karnataka 562112, India.

An exclusive synthesis of benzo-oxazine, benzo-oxazepine, and benzo-oxazocine from aryl propanal and 2-(hydroxyamino)phenyl alcohol under metal-free conditions is described. O atom transfer and formation of new C═O, C-N, and C-O bonds occur at room temperature to form six-, seven-, and eight-membered heterocycles under one-pot reaction conditions without using an external oxidant and base. The photophysical properties are studied using ultraviolet-visible absorption and photoluminescence. The mechanistic elucidation is well supported by control experiment and literature precedents.
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http://dx.doi.org/10.1021/acs.orglett.1c02895DOI Listing
November 2021

Chemoselective [3 + 2] annulation of oxime acetate with 2-aryl-3-ethoxycarbonyl-pyrroline-4,5-dione: an entry to pyrrolo[2,3-]pyrrole derivatives.

Org Biomol Chem 2021 09 22;19(36):7875-7882. Epub 2021 Sep 22.

Department of Organic Synthesis & Process Chemistry, CSIR-Indian Institute of Chemical Technology, Hyderabad - 500007, India.

A novel chemoselective [3 + 2] annulation reaction of easily accessible ketoxime acetate with 2-aryl-3-ethoxycarbonyl pyrroline-4,5-dione has been developed for the synthesis of unknown pyrrolo[2,3-]pyrrole frameworks. This method involves copper-mediated N-O bond cleavage followed by the formation of carbon-carbon and carbon-nitrogen bonds. This operationally simple protocol provides broader functional group compatibility and good yields.
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http://dx.doi.org/10.1039/d1ob00990gDOI Listing
September 2021

Gold-catalyzed synthesis of 1-isochromene-4-carbaldehydes oxidative cascade cyclization.

Org Biomol Chem 2021 04;19(16):3634-3643

Fluoro and Agrochemicals Department, CSIR-Indian Institute of Chemical Technology, Hyderabad, 500007, India. and Academy of Scientific and Innovative Research, Ghaziabad, 201002, India.

An efficient gold-catalyzed formation of indenylidene-derived 1H-isochromene-4-carbaldehydes from substituted 1,5,10-triyne-O-silanes was developed under mild reaction conditions. In this reaction, gold-catalyzed selective oxidation, 1,2-migration, nucleophilic addition and then 5-endo-dig cyclization took place regioselectively. The indenylidene-derived isochromene-4-carbaldehydes were synthesized in moderate to very good yields via the formation of new C-C and C-O bonds in one pot.
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http://dx.doi.org/10.1039/d1ob00066gDOI Listing
April 2021

Polymorphic forms of antiandrogenic drug nilutamide: structural and thermodynamic aspects.

Phys Chem Chem Phys 2021 Apr;23(16):9695-9708

G. A. Krestov Institute of Solution Chemistry of the Russian Academy of Sciences, 1 Akademicheskaya St., 153045 Ivanovo, Russia.

Attempts to obtain new cocrystals of nonsteroidal antiandrogenic drug nilutamide produced alternative polymorphic forms of the compound (Form II and Form III) and their crystal structures were elucidated by single-crystal X-ray diffraction. Apart from the cocrystallization technique, lyophilization was found to be an effective strategy for achieving polymorph control of nilutamide, which was difficult to obtain by other methods. The physicochemical properties and relative stability of the commercial Form I and newly obtained Form II were comprehensively investigated by a variety of analytical methods (thermal analysis, solution calorimetry, solubility, and sublimation), whereas for Form III, only a handful of experimental parameters were obtained due to the elusive nature of the polymorph. Form I and Form II were found to be monotropically related, with Form I being confirmed as the thermodynamically most stable solid phase. In addition, the performance of different DFT-D and semi-empirical schemes for lattice energy calculation and polymorph energy ranking was compared and analysed. Lattice energy calculations using periodic DFT at B3LYP-D3/6-31(F+)G(d,p) and PBEh-3c/def2-mSVP levels of theory were found to provide the most accurate lattice energy values for Form I against experimental data, while PIXEL and PBEh-3c/def2-mSVP were the only methods that predicted the correct order of stability of Forms I and II.
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http://dx.doi.org/10.1039/d1cp00793aDOI Listing
April 2021

Direct Access for the Regio- and Stereoselective Synthesis of -Alkenylpyrazoles and Chromenopyrazoles.

J Org Chem 2021 02 19;86(3):2271-2282. Epub 2021 Jan 19.

Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India.

A highly regio- and stereoselective method was developed for the preparation of -alkenylpyrazoles and chromenopyrazoles by the reaction of -tosylhydrazones and salicyl -tosylhydrazones with alkynes under neat conditions in the presence of La(OTf). The present study was found to be efficient and convenient for direct access to -alkenylpyrazoles and chromenopyrazoles through C-C, C-N, and C-O bond forming reactions. Structure assignment of -alkenylpyrazole compound was confirmed by X-ray analysis.
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http://dx.doi.org/10.1021/acs.joc.0c02421DOI Listing
February 2021

Gold(iii) promoted formation of dihydroquinazolinones: double X-H activation by gold.

RSC Adv 2020 Sep 28;10(59):35681-35691. Epub 2020 Sep 28.

Fluoro and Agrochemicals Department, CSIR-Indian Institute of Chemical Technology Hyderabad 500007 India

An efficient 2-furyl gold-carbene promoted synthetic method was developed for the formation of dihydroquinazolinones from enynones by dual insertion of anthranilamides. In this organic transformation a new C-O and two C-N bond formations occurred and dihydroquinazolinones were obtained with a quaternary centre in moderate to very good yields in one-pot synthesis.
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http://dx.doi.org/10.1039/d0ra06537dDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC9056963PMC
September 2020

Correction: Tandem Prins cyclization for the synthesis of indole fused spiro-1,4-diazocane scaffolds.

Org Biomol Chem 2020 Sep;18(36):7224

Fluoro & Agrochemicals, CSIR-Indian Institute of Chemical Technology, Hyderabad, India. and Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, UP, 201002, India.

Correction for 'Tandem Prins cyclization for the synthesis of indole fused spiro-1,4-diazocane scaffolds' by Chandrashekhar Rapelli et al., Org. Biomol. Chem., 2020, 18, 6710-6715, DOI: 10.1039/D0OB01384F.
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http://dx.doi.org/10.1039/d0ob90122aDOI Listing
September 2020

Tandem Prins cyclization for the synthesis of indole fused spiro-1,4-diazocane scaffolds.

Org Biomol Chem 2020 09 21;18(34):6710-6715. Epub 2020 Aug 21.

Fluoro & Agrochemicals, CSIR-Indian Institute of Chemical Technology, Hyderabad, India.

A novel strategy has been developed for the synthesis of indole fused spiro-1,4-diazocane derivatives. Using a tandem Prins cyclization, this is the first report on the synthesis of eight-membered spirodiazocane scaffolds, which are less accessible due to ring strain but more relevant to drug discovery.
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http://dx.doi.org/10.1039/d0ob01384fDOI Listing
September 2020

Indole-fused spirochromenes as potential anti-tubercular agents: design, synthesis and in vitro evaluation.

Mol Divers 2021 Nov 30;25(4):2137-2148. Epub 2020 May 30.

Department of Chemistry, Satavahana University, Karimnagar, Telangana State, 505001, India.

As part of an ongoing effort to develop new anti-tubercular agents, a series of novel indole-fused spirochromene hybrids (7a-l) were efficiently synthesized in excellent yields by the popular 'Fisher-Indole synthesis' approach. The structure elucidation of the target compounds was carried out by different spectral techniques including H-NMR, C-NMR, ESI Mass, and FTIR analysis. Additionally, the proposed structure of 7i was proved by single-crystal X-ray analysis. These compounds (7a-l) were screened for in vitro anti-tubercular activity against Mycobacterium tuberculosis H37Rv (ATCC 27294) strain. The results showed that most of the targets exhibited promising antimycobacterial activity with MICs of 1.56-6.25 μg/mL and weak cytotoxicity (19.93-32.16% at 50 μg/mL). Among them, compound 7l was found to be the most active compound (MIC of 1.56 μg/mL) with a good safety profile (32.16% at 50 μg/mL).
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http://dx.doi.org/10.1007/s11030-020-10108-zDOI Listing
November 2021

Access to pyrrolo[2,1-a]isoindolediones from oxime acetates and ninhydrin via Cu(i)-mediated domino annulations.

Org Biomol Chem 2020 03;18(9):1743-1746

Department of Organic Synthesis and Process Chemistry, CSIR-Indian Institute of Chemical Technology, Hyderabad 500007, India. and AcSIR (Academy of Scientific & Innovative Research), Ghaziabad, 201 002, India.

A copper-mediated domino condensation reaction of readily accessible oxime acetates with ninhydrin is reported to afford pyrrolo[2,1-a]isoindolediones via new C-C & C-N bond formations. A wide range of oxime acetates were shown to generally participate in the reaction to produce the condensed products in excellent yields. The necessary control experiments were performed and the mechanism is proposed to involve sequentially the formation of iminium radical via Cu-mediated N-O bond cleavage of oxime acetates, addition of the radical to ninhydrin and rearrangement via ring expansion.
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http://dx.doi.org/10.1039/d0ob00058bDOI Listing
March 2020

Catalyst-Free Regioselective [3+2] Cycloadditions of α,β-unsaturated N-arylnitrones with Alkenes to Access Functionalized Isoxazolidines: A DFT Study.

Chem Asian J 2020 Mar 24;15(6):899-903. Epub 2020 Feb 24.

Centre for Nano and Material Sciences, Jain University, Jain Global Campus, Bangalore, Karnataka, 562112, India.

The catalyst-free regioselective [3+2]-cycloaddition of α,β-unsaturated N-arylnitrones with alkenes are developed. The series of synthetically important functionalized isoxazolidines are prepared in good to excellent yields by step economic pathway under ligand and transition-metal-free conditions. The regioselective cycloaddition pathway supported by control experiment and computational study.
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http://dx.doi.org/10.1002/asia.201901754DOI Listing
March 2020

Two novel polymorphic forms of iron-chelating agent deferiprone.

Acta Crystallogr C Struct Chem 2020 02 31;76(Pt 2):193-200. Epub 2020 Jan 31.

Center for X-ray Crystallography, Analytical Division, CSIR-Indian Institute of Chemical Technology, Hyderabad, Telangana 500 007, India.

Thalassemia is a genetic blood disorder requiring life-long blood transfusions. This process often results in iron overload and can be treated by an iron-chelating agent, like deferiprone (3-hydroxy-1,2-dimethylpyridin-4-one), CHNO, in an oral formulation. The first crystal structure of deferiprone, (Ia), was reported in 1988 [Nelson et al. (1988). Can. J. Chem. 66, 123-131]. In the present study, two novel polymorphic forms, (Ib) and (Ic), of deferiprone were identified concomitantly with polymorph (Ia) during the crystallization experiments. Polymorph (Ia) was redetermined at low temperature for comparison of the structural features and lattice energy values with polymorphs (Ib) and (Ic). Polymorph (Ia) crystallized in the orthorhombic space group Pbca, whereas both polymorphs (Ib) and (Ic) crystallized in the monoclinic space group P2/c. The asymmetric units of (Ia) and (Ib) contain one deferiprone molecule, while polymorph (Ic) has three crystallographically independent molecules (A, B and C). All three polymorphs have similar hydrogen-bonding features, such as an R(10) dimer formed by O-H...O hydrogen bonds, an R(20) tetramer formed by C-H...O hydrogen bonds and π-π interactions, but the polymorphs differ in their molecular arrangements in the solid state and are classified as packing polymorphs. O-H...O and C-H...O hydrogen bonds lead to the formation of two-dimensional hydrogen-bonded parallel sheets which are interlinked by π-π stacking interactions. In the three-dimensional crystal packing, the deferiprone molecules were aggregated as corrugated sheets in polymorphs (Ia) and (Ic), whereas in polymorph (Ib), they were aggregated as a square-grid network. The characteristic crystalline peaks of polymorphs (Ia), (Ib) and (Ic) were established through powder X-ray diffraction analysis. The Rietveld analysis was also performed to estimate the contribution of the polymorphs to the bulk material.
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http://dx.doi.org/10.1107/S2053229620000959DOI Listing
February 2020

Synthesis, in vitro, and in vivo (Zebra fish) antitubercular activity of 7,8-dihydroquinolin-5(6H)-ylidenehydrazinecarbothioamides.

Bioorg Chem 2020 03 25;96:103626. Epub 2020 Jan 25.

Fluoro and Agrochemicals Division, CSIR - Indian Institute of Chemical Technology, Hyderabad 500007, Telangana, India; Academy of Scientific and Innovative Research, CSIR - Indian Institute of Chemical Technology, Hyderabad 500 007, Telangana, India. Electronic address:

We, herein, describe the synthesis of a series of novel aryl tethered 7,8-dihydroquinolin-5(6H)-ylidenehydrazinecarbothioamides 4a-v, which showed in vitro and in vivo antimycobacterial activity against Mycobacterium tuberculosis (Mtb) H37Rv. The intermediates dihydro-6H-quinolin-5-ones 3a-v were synthesized from β-enaminones, reacting with cyclochexane-1,3-dione/5,5-dimethylcyclohexane-1,3-dione and ammonium acetate using a modified Bohlmann-Rahtz reaction conditions. They were further reacted with thiosemicarbazide to give the respective hydrazine carbothioamides 4a-v. All the new analogues 4a-v, were characterized by their NMR and mass spectral data analysis. Among the twenty-two compounds screened for in vitro antimycobacterial activity against Mycobacterium tuberculosis H37Rv (ATCC27294), two compounds, 4e and 4j, exhibited the highest inhibition with an MIC of 0.39 µg/mL. Compounds 4a, 4g, and 4k were found to inhibit Mtb at an MIC of 0.78 µg/mL. Hydrazinecarbothioamides 4a-k, exhibited enhanced activity than dihydroquinolinones 3a-k. The observed increase in potency provides a clear evidence that hydrazinecarbothioamide is a potential pharmacophore, collectively imparting synergistic effect in enhancing antitubercular activity of the dihydroquinolinone core. The in vivo (Zebra fish) antimycobacterial screening of the in vitro active molecules led to the identification of a hit compound, 4j, with significant activity in the Mtb nutrient starvation model (2.2-fold reduction). Docking studies of 4j showed a hydrogen bond with the P156 residue of the protein.
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http://dx.doi.org/10.1016/j.bioorg.2020.103626DOI Listing
March 2020

Visible-light-driven metal-free aerobic synthesis of highly diastereoselective phosphinoylpyrroloindoles.

Org Biomol Chem 2020 Feb 30;18(7):1354-1358. Epub 2020 Jan 30.

Department of Organic Synthesis and Process Chemistry, CSIR-Indian Institute of Chemical Technology (CSIR-IICT), Hyderabad 500007, India.

A visible-light-driven metal-free phosphorus radical mediated construction of 2-phosphinoyl-3H-pyrrolo[1,2,a]indoles is described. This mild tandem phosphinoylation/cyclization protocol utilizes air as a green oxidant and proceeds in a short span of time at room temperature with high functional group tolerance, and excellent chemo- and diastereoselectivity.
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http://dx.doi.org/10.1039/c9ob02730kDOI Listing
February 2020

Usnic Acid Enaminone-Coupled 1,2,3-Triazoles as Antibacterial and Antitubercular Agents.

J Nat Prod 2020 01 20;83(1):26-35. Epub 2019 Dec 20.

Medicinal Chemistry and Antimycobacterial Research Laboratory, Pharmacy Group , Birla Institute of Technology & Science-Pilani , Hyderabad Campus, Jawahar Nagar , Hyderabad - 500078 , Telangana , India.

(+)-Usnic acid, a product of secondary metabolism in lichens, has displayed a broad range of biological properties such as antitumor, antimicrobial, antiviral, anti-inflammatory, and insecticidal activities. Interested by these pharmacological activities and to tap into its potential, we herein present the synthesis and biological evaluation of new usnic acid enaminone-conjugated 1,2,3-triazoles - as antimycobacterial agents. (+)-Usnic acid was condensed with propargyl amine to give usnic acid enaminone with a terminal ethynyl moiety. It was further reacted with various azides - under copper catalysis to give triazoles - in good yields. Among the synthesized compounds, saccharin derivative proved to be the most active analogue, inhibiting () at an MIC value of 2.5 μM. Analogues and , with 3,4-difluorophenacyl and 2-acylnaphthalene units, respectively, inhibited at MIC values of 5.4 and 5.3 μM, respectively. Among the tested Gram-positive and Gram-negative bacteria, the new derivatives were active on , with compounds [3-(trifluoromethyl)phenacyl] and (N-acylmorpholinyl) showing inhibitory concentrations of 41 and 90.7 μM, respectively, while they were inactive on the other tested bacterial strains. Overall, the study presented here is useful for converting natural (+)-usnic acid into antitubercular and antibacterial agents via incorporation of enaminone and 1,2,3-triazole functionalities.
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http://dx.doi.org/10.1021/acs.jnatprod.9b00475DOI Listing
January 2020

Base Mediated Tandem Vinylogous Addition and Cyclization of γ-Phosphonyl/Sulfonyl Crotonates and Ynones: Synthesis of Functionalized 2-Pyrones.

ACS Omega 2019 Nov 30;4(20):18846-18854. Epub 2019 Oct 30.

OSPC Department, CSIR-Indian Institute of Chemical Technology, Habsiguda, Hyderabad 500007, India.

A general method for highly functionalized 2-pyrones via a base-mediated sequential vinylogous addition and cyclization of γ-phosphonyl/sulfonyl crotonates and ynones are described. An exclusive E-geometry with respect to the newly generated olefin substituent at C3 of pyrone was observed. Imino glyoxalates and glycine imines similarly reacted with ynones to deliver 3-imino pyrones.
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http://dx.doi.org/10.1021/acsomega.9b02874DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6854826PMC
November 2019

Synthesis and evaluation of a novel quinoline-triazole analogs for antitubercular properties via molecular hybridization approach.

Bioorg Med Chem Lett 2019 10 5;29(20):126671. Epub 2019 Sep 5.

Department of Organic Synthesis & Process Chemistry, CSIR-Indian Institute of Chemical Technology, Hyderabad 500007, India; Academy of Scientific and Innovative Research (AcSIR), CSIR-Human Resource Development Centre (CSIR-HRDC) Campus, Ghaziabad, Uttar Pradesh 201002, India. Electronic address:

Towards a quest for establishing new antitubercular agents, we have designed new quinoline-triazole hybrid analogs in a six-step reaction sequence involving versatile reactions like Vilsmeier-Haack and click reaction protocol. The design is based on the structural modification of bedaquiline moiety and involves molecular hybridization approach. The structure of the synthesized product was elucidated by single crystal X-ray diffraction study. The synthesized target compounds were screened for their antitubercular activity against Mycobacterium bovis. Interestingly, two compounds of the series (8d and 8m) showed significant inhibition with MIC of 31.5 and 34.8 μM. Compounds bearing 3-fluoro phenyl and n-octyl groups on the 1,2,3-triazole ring emerged as the most potent leads among the compounds tested. Further these hit compounds were also screened for their cytotoxic effect on human embryonic kindey 293 (HEK293) cells and other cancer cell lines such as HeLa (Cervical), PC3 (Prostate), Panc-1 (Pancreatic) and SKOV3 (Ovarian) indicating to be safer with the minimal cytotoxicity.
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http://dx.doi.org/10.1016/j.bmcl.2019.126671DOI Listing
October 2019

Gold-Catalyzed Synthesis of 6-Hydroxyindoles from Alkynylcyclohexadienones and Substituted Amines.

J Org Chem 2019 Sep 11;84(18):12228-12236. Epub 2019 Sep 11.

Fluoro and Agrochemicals Department , Academy of Scientific and Innovative Research , Ghaziabad 201002 , India.

An efficient gold-catalyzed formation of 6-hydroxyindoles from substituted alkynylcyclohexadienones and amines have been developed. In this reaction two new C-N bonds were formed, and moderate to very good yields of the 6-hydroxyindole derivatives were obtained in one pot. This organic transformation tolerates a range of substituted alkynylcyclohexadienones and amines, which resulted in 6-hydroxyindole derivatives selectively.
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http://dx.doi.org/10.1021/acs.joc.9b02023DOI Listing
September 2019

Organocatalytic Enantioselective Mannich Reaction: Direct Access to Chiral β-Amino Esters.

ACS Omega 2019 Jan 29;4(1):2168-2177. Epub 2019 Jan 29.

Fluoro & Agrochemicals and Laboratory of X-ray Crystallography, CSIR-Indian Institute of Chemical Technology, Hyderabad 500007, India.

An asymmetric Mannich reaction has been developed to generate chiral β-amino esters in good yields with excellent enantiomeric excesses (ee, up to 99%) using a chiral bifunctional thiourea catalyst derived from (,)-cyclohexyldiamine. This is the first report on the addition of 3-indolinone-2-carboxylates to -Boc-benzaldimines generated in situ from α-amidosulfones, which proceeds under mild conditions.
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http://dx.doi.org/10.1021/acsomega.8b02132DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6648529PMC
January 2019

Ru(II)-Catalyzed Oxidative Functionalization of Arylhydrazine-1,2-dicarboxylates with Internal Alkynes for the Synthesis of Enecarbamates.

ACS Omega 2018 Aug 22;3(8):9746-9753. Epub 2018 Aug 22.

Centre for Semiochemicals and Laboratory of X-ray Crystallography, CSIR-Indian Institute of Chemical Technology, Hyderabad 500 007, India.

A novel method has been developed for the synthesis of highly substituted enecarbamates and trisubstituted alkenes from arylhydrazine-1,2-dicarboxylates and 1,2-disubstituted alkynes through a sequential C-C and C-N bond formation. It is entirely a new strategy to produce enecarbamates in a highly regio- and stereoselective manner.
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http://dx.doi.org/10.1021/acsomega.8b01118DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6644781PMC
August 2018

Synthetic Access to Cyclopenta[]inden-2(1)-ones from Morita-Baylis-Hillman Products of 2-Alkynyl Benzaldehydes.

ACS Omega 2018 Nov 19;3(11):15734-15742. Epub 2018 Nov 19.

Department of Organic Synthesis & Process Chemistry and Centre for X-Ray Crystallography, CSIR-Indian Institute of Chemical Technology, Hyderabad 500007, India.

A new strategy for the synthesis of cyclopenta[]inden-2(1)-ones has been developed. An intramolecular Pauson-Khand reaction of the Morita-Baylis-Hillman (MBH) adducts, derived from 2-alkynyl benzaldehydes, provided the consequent novel cyclopenta[]inden-2(1)-ones bearing multifunctionalities including an ester group at the fused ring junction (-carbon center). The generality of this approach was illustrated by studying the several MBH derivatives containing diverse substitutions/functionalities.
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http://dx.doi.org/10.1021/acsomega.8b02111DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6644149PMC
November 2018

Cationic Pd(IV)-Induced Highly Diastereoselective Arylative Cascade Cyclization of Allene-Tethered Cyclohexadienones Leading to Oxygenated Bicyclic Motifs.

Org Lett 2019 Aug 30;21(16):6300-6304. Epub 2019 Jul 30.

Analytical Division , CSIR-Indian Institute of Chemical Technology , Hyderabad 500 007 , Telangana , India.

A cationic Pd(IV)-catalyzed arylative hydroxylation-Micheal addition of allenyl-tethered cyclohexadienones was developed. This relay reaction could afford highly diastereoselective various functionalized arylative 1,4-dioxane -bicyclic structural units with good to high yields. The striking features revealed from these studies is the necessity of Selectfluor and the oxidative hydroxylation originating from water initiated by F-Pd(IV) catalysis. A plausible mechanism was also proposed for this variant observation.
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http://dx.doi.org/10.1021/acs.orglett.9b02180DOI Listing
August 2019

A gold-catalyzed facile intramolecular rearrangement and cyclization sequence for synthesis of 2,5-dihydrofurans.

Org Biomol Chem 2019 Jun;17(24):6015-6024

Department of Fluoro and Agrochemicals, CSIR-Indian Institute of Chemical Technology, Hyderabad, 500007, India.

An efficient gold-catalyzed intramolecular rearrangement and cyclization protocol was developed for synthesis of 2,5-dihydrofuran derivatives from O-propargyl β-enaminones. In this organic transformation new C-C and C-O bonds are formed under mild reaction conditions; this includes the formation of a quaternary centre.
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http://dx.doi.org/10.1039/c9ob00756cDOI Listing
June 2019

Gold-carbene assisted formation of tetraarylmethane derivatives: double X-H activation by gold.

Org Biomol Chem 2019 May;17(19):4856-4864

Department of Fluoro and Agrochemicals, CSIR-Indian Institute of Chemical Technology, Hyderabad, 500007, India.

An efficient gold-carbene promoted generation of tetraarylmethane derivatives from enynones and indoles was accomplished by the formation of a new C-O bond and two C-C bonds. It is significant that (2-furyl) gold-carbene assisted addition of two nucleophiles resulted in the formation of tetraarylmethane derivatives with a quaternary centre in moderate to good yields in one pot.
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http://dx.doi.org/10.1039/c9ob00470jDOI Listing
May 2019

Transition metal-free functionalized hydration of alkynes: one-pot synthesis of fluorinated β-keto-imidates using Selectfluor.

Org Biomol Chem 2019 05;17(18):4440-4445

Centre for Nano and Material Sciences, Jain Global Campus, JAIN (Deemed-to-be-University), Bangalore, Karnataka 562112, India.

A transition metal-free, four-component one-pot synthesis of polyfunctionalized fluorinated β-keto-imidates via the functionalized hydration of alkynes has been described. The intermediate 1,3-ketoamino moiety was obtained from easily accessible arylpropioladehyde and arlyhydroxylamine and was treated with Selectfluor delivering fluorinated β-keto-imidates. A wide variety of functional groups are tolerated under mild reaction conditions and the product applicability is highlighted.
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http://dx.doi.org/10.1039/c9ob00527gDOI Listing
May 2019
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