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Welcome to RK Group

π-Activation and
Natural Products (Asymmetric) Synthesis Lab 

Organic Chemistry Division
CSIR-National Chemical Laboratory, Pune, INDIA

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Dr. Ravindar Kontham
Principal Scientist-CSIR/Associate Professor-AcSIR
Division of Organic Chemistry
CSIR-National Chemical Laboratory
Dr. Homi Bhabha Road Pune-411008, India.
Phone Office: +91-20-2590 2301
Mobile: +91 750 788 9557
e-mail: k.ravindar@ncl.res.in/ konthamravindar@gmail.com

Dear Friends! Welcome to our website! Our research group is actively working in organic synthesis and medicinal chemistry. Our primary research focuses on cool projects like a practical stereo-selective total synthesis of complex biologically potent natural products and medicinal chemistry. We investigate to preparation more powerful, less toxic, and structurally simplified analogs of various complex natural products via structural modification of natural parent molecules. We also work on developing new synthetic methodologies involving π-activation induced cycloisomerization of alkynes and cascade polycyclizations. 

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Natural products have long been regarded as ‘nature’s medicine chest,’ providing a rich source of lead compounds as invaluable platforms for developing front-line drugs. 63% of all new drugs approved by the FDA between 1981 and 2006 were inspired by natural products. Our research focuses on making and modifying naturally occurring bioactive compounds that have been isolated from plants, animal tissue, microbes, or marine and soil organisms, which are rare or hard to isolate in abundance. These compounds provide rich and diverse chemical structures that challenge the synthetic chemist to develop a new flexible synthetic methodology for their construction. Preparing synthetic analogs of the natural compound may improve biological activity and provide an understanding of the mechanism of action of the naturally occurring compound.

Recent Publications 

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Aminoacylase efficiently hydrolyses fatty acid amino acid conjugates of Helicoverpa armigera potentially to increase the pool of glutamine

Gopal S. Kallure , Shubhranshu Shekhar Sahoo , Rutuja S. Kale, Vitthal T. Barvkar , Ravindar Kontham , Ashok P. Giri, Insect Biochemistry and Molecular Biology 165 (2024) 104070,  https://doi.org/10.1016/j.ibmb.2024.104070

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Divergent access to polycyclic spiro- and fused-N,O-ketals through Bi(OTf)3-catalyzed [4+2]-annulation of cyclic N-sulfonyl ketimines and alkynols

Ashwini K. Nakate, Priyanka Kataria, Pooja I. Sambherao, Gamidi Rama Krishna and  Ravindar Kontham , Chem. Commun., 2024, 60, 1144, https://doi.org/10.1039/D3CC05599J

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Concise and collective total syntheses of 2,4-disubstituted furan-derived natural products from hydroxyoxetanyl ketones

Shubhranshu Shekhar Sahoo, Priyanka Kataria and  Ravindar Kontham*, Org. Biomol. Chem., 2024, 22, 1475, https://doi.org/10.1039/D3OB01924A

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Regioselective Synthesis of Benzannulated [5,6]-Oxaspirolactones via Cu(II)-Catalyzed Cycloisomerization of 2‑(5- Hydroxyalkynyl)benzoates

Sagar S. Thorat,∥ Sagar P. Shimpi,∥ Pooja I. Sambherao, Gamidi Rama Krishna, and Ravindar Kontham.J. Org. Chem., 2023, https://doi.org/10.1021/acs.joc.3c01751

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Divergent Synthesis of Oxepino-Phthalides and [5,5]- Oxaspirolactones through [2 + 2 + 2]- and [2 + 3]-Annulation of Alkynyl Alcohols with α‑Ynone-Esters

Digambar A. Kambale,§ Balasaheb R. Borade,§ Ramavath Vinodkumar, and Ravindar KonthamJ. Org. Chem., 2023, J. Org. Chem. 2023, 88, 12597−12612

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Studies Directed Toward the Total Synthesis of Nannocystin A

R. Nomula, M. S. Pratapure, R. Kontham.; ChemistrySelect 2022, 7, e202203893

 doi.org/10.1002/slct.202203893

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Concise Total Synthesis of (+)-Lanceolactone A: Revision of Absolute Stereochemistry

Borade, B. R.; Kontham, R.; J. Org. Chem., 2022, 87 (19), 12867-1287. 

https://doi.org/10.1021/acs.joc.2c01450

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Enceleamycins A–C, Furo-Naphthoquinones from Amycolatopsis sp. MCC0218: Isolation, Structure Elucidation, and Antimicrobial Activity

Khan, A.; Said, M. S.; Borade, B. R.; Gonnade, R.; Barvkar, V.; Kontham, R.; Dastager, S. G. J. Nat. Prod., 2022, 85, 1267-1273.

https://doi.org/10.1021/acs.jnatprod.1c01160

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Ready Access to Benzannulated [5,5]-Oxaspirolactones Using Au(III)-Catalyzed Cascade Cyclizations

Mankad, Y.; Thorat, S. S.; Das, P.; Gamidi, R. K.; Kontham, R.; Reddy, D. S. J. Org. Chem. 2022, 87, 3025–3041.

https://doi.org/10.1021/acs.joc.1c02843

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Silver-catalyzed [3+3]-annulation cascade of alkynyl alcohols and α,β-unsaturated ketones for the regioselective assembly of chromanes

Nakate, A. K.; Thorat, S. S.; Jain, S.; Krishna G.; Vanka, K.; Kontham, R. Org. Chem. Front, 2022, 9, 802-809.

https://doi.org/10.1039/D1QO01643A

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Studies directed toward the synthesis of hedycoropyrans: total synthesis of des-hydroxy (-)-hedycoropyran B (ent-rhoiptelol B)

Kataria, P.; Nomula, R.; Kontham, R. Org. Biomol. Chem., 2022, 20, 444-463. 

doi.org/10.1039/D1OB01972D

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Stereoselective Total Synthesis of (±)-Pleurospiroketals A and B

Thorat, S. S.; Krishna G.; Kontham, R. J. Org. Chem., 2021, 86, 13572-13582. 

doi.org/10.1021/acs.joc.1c01634

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Bismuth(III)-catalyzed bis-cyclization of propargylic diol-esters: a unified approach for the synthesis of  [5,5]- and [6,5]-oxaspirolactones

Kambale, D. A.;Borade, B. R.;Kontham, R. Org. Biomol. Chem., 2021, 19, 6618-6622. 

DOI: https://doi.org/10.1039/D1OB00974E

Strategies for the synthesis of furo-pyranones and their application in the total synthesis of related natural products

Thorat, S. S.; Kontham, R. Org. Chem. Front, 2021, 8, 2110-2162. 

DOI-doi.org/10.1039/D0QO01421D

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Total Synthesis of Beshanzuenone D & It's Epimers and Abiespiroside A 

Borade, B. R.; Ruchi Dixit.;Kontham, R. Org. Lett., 2020, 22, 8561-8565. 

DOI: https://dx.doi.org/10.1021/acs.orglett.0c03157

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Recent advances in the synthesis of oxaspirolactones and their application in the total synthesis of related natural products

Thorat, S. S.; Kontham, R. Org. Biomol. Chem., 2019, 17, 7270-7292. 

DOI: 10.1039/c9ob01212e

TiCl4-n-Bu3N-mediated cascade annulation of ketones with α-ketoesters: a facilesynthesis of highly substituted fused γ-alkylidene-butenolides

Palange, M. N.; Gonnade, R. G.;Kontham, R. Org. Biomol. Chem., 2019, 17, 5749-5759. 

DOI: 10.1039/c9ob00649d

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Fe(III)-Catalyzed Diastereoselective Friedel−Crafts Alkylation−Hemiketalization−Lactonization Cascade for the Synthesis of Polycyclic Bridged 2‑Chromanol Lactones

Borade, B. R.; Nomula, R.; Gonnade, R. G.;Kontham, R. Org. Lett.,  2019, 21, 2629-2633. 

DOI: 10.1021/acs.orglett.9b00614

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Four-Step Total Synthesis of (+)-Yaoshanenolides A and B

Thorat, S. S.; Palange, M. N.; Kontham, R. ACS Omega. 2018, 3, 7036-7045. 

DOI: 10.1021/acsomega.8b00701

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Bismuth(III)-catalyzed cycloisomerization and (hetero)arylation of alkynols: a simple access to 2-(hetero)aryl tetrahydrofurans and tetrahydropyrans

Nakate, A. K.; Pratapure, M. S.; Kontham, R. Org. Biomol. Chem., 2018, 16, 3229-3240. 

DOI: 10.1039/c8ob00368h

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Synthesis of Furo[2,3‑b]pyran-2-ones through Ag(I)- or Ag(I)−Au(I)-Catalyzed Cascade Annulation of Alkynols and α‑Ketoesters

Thorat, S.S.; Kataria, P.; Kontham, R. Org. Lett. 2018, 20, 872-875. 

DOI: 10.1021/acs.orglett.7b04027

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Lewis acid catalyzed cascade annulation of alkynols with α-ketoesters: a facile access to γ-spiroketal-γ-lactones

Kambale, D. A.;Thorat, S. S.; Pratapure, M. S.; Gonnade, R. G.;Kontham, R. Chem. Commun., 2017, 53, 6641-6144.

DOI:10.1039/c7cc03668j

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Natural Product Targets Completed

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Org. Biomol. Chem., 2022, 20, 444―463.

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Pleurospiroketals_edited.png

J. Org. Chem. 2021, 86, 13572―13582.

Beshanzueanone D_edited.png
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Org. Lett. 2020, 22, 8561―8565.

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ACS Omega., 2018, 3, 7036―7045.

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J. Med. Chem. 2014, 57, 2511–2523.

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J. Org. Chem. 2014, 79, 7979–7999.

Org. Lett. 2013, 15, 6270―6273.

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Tetrahedron Lett. 2013, 54, 3227-3229.

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Synlett 2010, 1, 51–54.

Aculeatin D_edited.png
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Synthesis 2010, 5, 797–802.

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Synlett. 2009, 17, 2828―2830.

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Synthesis 2009, 18, 3157―3161.

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Helvetica Chimica Acta. 2010, 93, 1432―1438.

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