1
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Vinodkumar R, Nakate AK, Sharma H, Vanka K, Rama Krishna G, Kontham R. Brønsted Acid-Promoted Cyclodimerization of α,β-Unsaturated γ-Ketoesters: Construction of Fused Pyrano-ketal-lactones and γ-Ylidene-butenolides. ACS OMEGA 2024; 9:19859-19878. [PMID: 38737031 PMCID: PMC11079881 DOI: 10.1021/acsomega.3c08873] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/08/2023] [Revised: 12/12/2023] [Accepted: 01/09/2024] [Indexed: 05/14/2024]
Abstract
Unprecedented MsOH-promoted diastereoselective cascade dimerization and intramolecular lactonization of readily accessible α,β-unsaturated γ-ketoesters are presented. The results obtained in this work, control experiments, and density functional theory (DFT) calculations suggested that the initial enolization and E to Z isomerization/equilibration of olefin (C=C) of substrate α,β-unsaturated γ-ketoesters give a Z-isomer preferentially over an E-isomer. Subsequently, the Z-isomer undergoes intermolecular annulation with α,β-unsaturated γ-ketoesters via domino Michael addition/ketalization/lactonization steps to furnish fused tetracyclic pyrano-ketal-lactone. However, the Z-isomer prefers intramolecular trans-esterification in a competing pathway and gives bicyclic γ-ylidene-butenolide. The key features of this work include simple Brønsted acid catalysis, the formation of three bonds, two rings, and three contiguous stereogenic centers in a single step, DFT calculations, and the assignment of relative stereochemistry through X-ray diffraction (XRD) and two-dimensional (2D) nuclear magnetic resonance (NMR) analyses.
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Affiliation(s)
- Ramavath Vinodkumar
- Organic
Chemistry Division, CSIR-National Chemical
Laboratory, Dr. Homi Bhabha Road, Pune 411008, India
- Academy
of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India
| | - Ashwini K. Nakate
- Organic
Chemistry Division, CSIR-National Chemical
Laboratory, Dr. Homi Bhabha Road, Pune 411008, India
- Academy
of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India
| | - Himanshu Sharma
- Physical
and Materials Chemistry Division, CSIR-National
Chemical Laboratory, Pune 411008, India
- Academy
of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India
| | - Kumar Vanka
- Physical
and Materials Chemistry Division, CSIR-National
Chemical Laboratory, Pune 411008, India
- Academy
of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India
| | - Gamidi Rama Krishna
- Organic
Chemistry Division, CSIR-National Chemical
Laboratory, Dr. Homi Bhabha Road, Pune 411008, India
- Center
for Materials Characterization, CSIR-National
Chemical Laboratory, Dr. Homi Bhabha Road, Pune 411008, India
| | - Ravindar Kontham
- Organic
Chemistry Division, CSIR-National Chemical
Laboratory, Dr. Homi Bhabha Road, Pune 411008, India
- Academy
of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India
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2
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Nakate AK, Kataria P, Sambherao PI, Krishna GR, Kontham R. 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. Chem Commun (Camb) 2024; 60:1144-1147. [PMID: 38189113 DOI: 10.1039/d3cc05599j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2024]
Abstract
Bismuth(III) triflate-catalyzed [4+2]-annulation of cyclic N-sulfonyl ketimines (derived from saccharin) and alkynyl alcohols (4-pentyn-1-ols and 5-hexyn-1-ols) has been reported. This cascade annulation provides a diverse array of polycyclic spiro-and-fused N,O-ketals with excellent substrate scope, good isolated yields, and diastereoselectivities under mild reaction conditions.
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Affiliation(s)
- Ashwini K Nakate
- Organic Chemistry Division, CSIR-National Chemical Laboratory, Dr Homi Bhabha Road, Pune 411008, India.
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India
| | - Priyanka Kataria
- Organic Chemistry Division, CSIR-National Chemical Laboratory, Dr Homi Bhabha Road, Pune 411008, India.
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India
| | - Pooja I Sambherao
- Organic Chemistry Division, CSIR-National Chemical Laboratory, Dr Homi Bhabha Road, Pune 411008, India.
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India
| | - Gamidi Rama Krishna
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India
- Centre for Materials Characterization, CSIR-National Chemical Laboratory, Dr Homi Bhabha Road, Pune 411008, India
| | - Ravindar Kontham
- Organic Chemistry Division, CSIR-National Chemical Laboratory, Dr Homi Bhabha Road, Pune 411008, India.
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India
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3
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Rathod AB, Borade BR, Sambherao PI, Kontham R. Bi(OTf) 3-promoted cascade annulation of hydroxy-pyranones and unsaturated γ-ketoesters for the construction of polycyclic bridged pyrano-furopyranones. Org Biomol Chem 2024; 22:496-500. [PMID: 38165227 DOI: 10.1039/d3ob01862h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2024]
Abstract
An efficient protocol for constructing complex three dimensional polycyclic bridged chromano-furopyranones and pyrano-furopyranones (closely related to bioactive natural products) via bismuth(III)-catalyzed cascade annulation of hydroxy-pyranones and unsaturated γ-ketoesters is presented. This process involves intermolecular Michael addition, intramolecular hemiketalization, lactonization, formation of one C-C bond and two C-O bonds, rings, and contiguous stereocenters.
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Affiliation(s)
- Akshay B Rathod
- Organic Chemistry Division, CSIR-National Chemical Laboratory Dr Homi Bhabha Road, Pune-411008, India.
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad-201002, India
| | - Balasaheb R Borade
- Organic Chemistry Division, CSIR-National Chemical Laboratory Dr Homi Bhabha Road, Pune-411008, India.
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad-201002, India
| | - Pooja I Sambherao
- Organic Chemistry Division, CSIR-National Chemical Laboratory Dr Homi Bhabha Road, Pune-411008, India.
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad-201002, India
| | - Ravindar Kontham
- Organic Chemistry Division, CSIR-National Chemical Laboratory Dr Homi Bhabha Road, Pune-411008, India.
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad-201002, India
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4
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Thorat SS, Shimpi SP, Sambherao PI, Rama Krishna G, Kontham R. Regioselective Synthesis of Benzannulated [5,6]-Oxaspirolactones via Cu(II)-Catalyzed Cycloisomerization of 2-(5-Hydroxyalkynyl)benzoates. J Org Chem 2023. [PMID: 38010985 DOI: 10.1021/acs.joc.3c01751] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2023]
Abstract
Spiroketals and oxaspirolactones are widely found in biologically active natural products, serving as important structural motifs. In this study, we present a Cu(II)-catalyzed cascade cycloisomerization of 2-(5-hydroxyalkynyl)benzoates, enabling the regioselective synthesis of benzannulated [5,6]-oxaspirolactones containing an isochromen-1-one moiety. This strategy offers a rapid and efficient approach to access a diverse array of benzannulated [5,6]-oxaspirolactones. The methodology presented here showcases a broad substrate scope, delivering good yields and scalability up to gram scale. The structures of the oxaspirolactones were unequivocally confirmed through single-crystal X-ray analysis and by analogy using 1H and 13C{1H} NMR data.
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Affiliation(s)
- Sagar S Thorat
- Organic Chemistry Division, CSIR-National Chemical Laboratory, Dr. Homi Bhabha Road, Pune 411008, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India
| | - Sagar P Shimpi
- Organic Chemistry Division, CSIR-National Chemical Laboratory, Dr. Homi Bhabha Road, Pune 411008, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India
| | - Pooja I Sambherao
- Organic Chemistry Division, CSIR-National Chemical Laboratory, Dr. Homi Bhabha Road, Pune 411008, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India
| | - Gamidi Rama Krishna
- Organic Chemistry Division, CSIR-National Chemical Laboratory, Dr. Homi Bhabha Road, Pune 411008, India
- Center for Materials Characterization, CSIR-National Chemical Laboratory, Dr. Homi Bhabha Road, Pune 411008, India
| | - Ravindar Kontham
- Organic Chemistry Division, CSIR-National Chemical Laboratory, Dr. Homi Bhabha Road, Pune 411008, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India
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5
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Kambale DA, Borade BR, Vinodkumar R, Kontham R. Divergent Synthesis of Oxepino-Phthalides and [5,5]-Oxaspirolactones through [2 + 2 + 2]- and [2 + 3]-Annulation of Alkynyl Alcohols with α-Ynone-Esters. J Org Chem 2023; 88:12597-12612. [PMID: 37611259 DOI: 10.1021/acs.joc.3c01301] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/25/2023]
Abstract
Unmasking the synthetic potential of alkyne functional group of alkynyl alcohols as surrogates of carbonyl compounds, herein we present the first Brønsted acid (TfOH)-catalyzed [2 + 2 + 2]-annulation of 4-pentyn-1-ols (possessing terminal alkyne) with α-ynone-esters to access tricyclic tetrahydro-oxepino-phthalides. Besides, an unprecedented synthesis of α-acetoaryl or α-alkynyl [5,5]-oxaspirolactones has been demonstrated by employing 4-pentyn-1-ols (possessing an internal alkyne) as an annulation partner, which proceeds through a divergent [2 + 3]-annulation pathway.
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Affiliation(s)
- Digambar A Kambale
- Organic Chemistry Division, CSIR-National Chemical Laboratory, Dr. Homi Bhabha Road, Pune411008, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India
| | - Balasaheb R Borade
- Organic Chemistry Division, CSIR-National Chemical Laboratory, Dr. Homi Bhabha Road, Pune411008, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India
| | - Ramavath Vinodkumar
- Organic Chemistry Division, CSIR-National Chemical Laboratory, Dr. Homi Bhabha Road, Pune411008, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India
| | - Ravindar Kontham
- Organic Chemistry Division, CSIR-National Chemical Laboratory, Dr. Homi Bhabha Road, Pune411008, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India
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6
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Xun L, Zhang Z, Zhou Y, Qin S, Fu S, Liu B. Stereodivergent Construction of [5,5]-Oxaspirolactones of Phainanoids. J Org Chem 2023; 88:3987-3991. [PMID: 36883240 DOI: 10.1021/acs.joc.2c03091] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/09/2023]
Abstract
A stereodivergent synthesis of [5,5]-oxaspirolactones of phainanoids is presented herein. Through precisely tuning the inherent substitution differences on cyclopropanol, a palladium-catalyzed cascade carbonylative lactonization enables the stereodivergent synthesis of [5,5]-oxaspirolactones of phainanoids.
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Affiliation(s)
- Lizhi Xun
- Key Laboratory of Green Chemistry and Technology of Ministry of Education, College of Chemistry, Sichuan University, Chengdu, Sichuan 610064, China
| | - Zhijiang Zhang
- Key Laboratory of Green Chemistry and Technology of Ministry of Education, College of Chemistry, Sichuan University, Chengdu, Sichuan 610064, China
| | - Yuqiao Zhou
- Key Laboratory of Green Chemistry and Technology of Ministry of Education, College of Chemistry, Sichuan University, Chengdu, Sichuan 610064, China
| | - Song Qin
- Key Laboratory of Green Chemistry and Technology of Ministry of Education, College of Chemistry, Sichuan University, Chengdu, Sichuan 610064, China
| | - Shaomin Fu
- Key Laboratory of Green Chemistry and Technology of Ministry of Education, College of Chemistry, Sichuan University, Chengdu, Sichuan 610064, China
| | - Bo Liu
- Key Laboratory of Green Chemistry and Technology of Ministry of Education, College of Chemistry, Sichuan University, Chengdu, Sichuan 610064, China
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7
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Asserese KA, Huang H. Palladium-Catalyzed Hydrocarbonylative Spirolactonization for Expedite Construction of Oxaspirolactones. Org Lett 2023; 25:1109-1113. [PMID: 36762968 DOI: 10.1021/acs.orglett.3c00019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/11/2023]
Abstract
A novel palladium-catalyzed cascade hydrocarbonylation of the alkene moiety followed by intramolecular spirolactonization of 2-vinylaryl hydroxyalkyl ketones has been developed, which offers efficient and expedited access to furnishing oxaspirolactones in high yields with high chemoselectivities. This new method is compatible with an array of functional groups and proceeds under mild reaction conditions with commercially available catalyst components.
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Affiliation(s)
- Ketema Alemayehu Asserese
- Hefei National Research Center for Physical Sciences at the Microscale and Department of Chemistry, University of Science and Technology of China, Hefei 230026, People's Republic of China
| | - Hanmin Huang
- Hefei National Research Center for Physical Sciences at the Microscale and Department of Chemistry, Center for Excellence in Molecular Synthesis of Chinese Academy of Sciences, University of Science and Technology of China, Hefei 230026, People's Republic of China
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8
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Bismuth(III)-catalyzed cascade condensation of alkynyl alcohols with terminal alkynes: a facile construction of propargyl cyclic ethers. Tetrahedron Lett 2022. [DOI: 10.1016/j.tetlet.2022.154274] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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9
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Borade BR, Kontham R. Concise Total Synthesis of (+)-Lanceolactone A: Revision of Absolute Stereochemistry. J Org Chem 2022; 87:12867-12876. [PMID: 36170601 DOI: 10.1021/acs.joc.2c01450] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A chiral-pool protecting-group-free five-step total synthesis of tetranorsesquiterpenoide (+)-lanceolactone A and all of its four stereoisomers using (S)-(+)-, and (R)-(-)-linalool (coriandrol) as building blocks is disclosed. The key steps involved in this synthetic route are regioselective ozonolysis, Au(I)-catalyzed cycloisomerization-induced construction of furan from alleneone, and dye-sensitized photo-oxidation (through 1O2; singlet oxygen) of hydroxyalkyl-tethered furan to access oxaspirolactone. After a thorough evaluation of electronic circular dichroism (ECD) and optical rotation data of all possible stereoisomers, the absolute configuration of natural lanceolactone A at the C4 and C7 positions has been assigned as (+)-(4S,7S), which is an enantiomer to the initially proposed structure (+)-(4R,7R). Further, these investigations led us to extend Feringa and Gawronski's CD correlation method to [5,5]- and [6,5]-oxaspirolactones.
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Affiliation(s)
- Balasaheb R Borade
- Organic Chemistry Division, CSIR-National Chemical Laboratory, Dr. Homi Bhabha Road, Pune 411008, India.,Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India
| | - Ravindar Kontham
- Organic Chemistry Division, CSIR-National Chemical Laboratory, Dr. Homi Bhabha Road, Pune 411008, India.,Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India
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10
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Gan Z, Cui D, Zhang H, Feng Y, Huang L, Gui Y, Gao L, Song Z. Trityl Cation-Catalyzed Hosomi-Sakurai Reaction of Allylsilane with β,γ-Unsaturated α-Ketoester to Form γ,γ-Disubstituted α-Ketoesters. Molecules 2022; 27:molecules27154730. [PMID: 35897907 PMCID: PMC9331905 DOI: 10.3390/molecules27154730] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2022] [Revised: 07/20/2022] [Accepted: 07/21/2022] [Indexed: 12/10/2022] Open
Abstract
(Ph3C)[BPh(F)4]-catalyzed Hosomi-Sakurai allylation of allylsilanes with β,γ-unsaturated α-ketoesters has been developed to give γ,γ-disubstituted α-ketoesters in high yields with excellent chemoselectivity. Preliminary mechanistic studies suggest that trityl cation dominates the catalysis, while the silyl cation plays a minor role.
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Affiliation(s)
| | | | | | | | | | | | - Lu Gao
- Correspondence: (L.G.); (Z.S.)
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11
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Yang WL, Shang XY, Luo X, Deng WP. Enantioselective Synthesis of Spiroketals and Spiroaminals via Gold and Iridium Sequential Catalysis. Angew Chem Int Ed Engl 2022; 61:e202203661. [PMID: 35446472 DOI: 10.1002/anie.202203661] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2022] [Indexed: 11/09/2022]
Abstract
The enantioselective cascade reaction between racemic 2-(1-hydroxyallyl)phenols and alkynols/alkynamides was realized by using a gold and iridium sequential catalytic system. In this procedure, the in situ generated exocyclic vinyl ethers or enamides undergo the asymmetric allylation/spiroketalization with π-ally-Ir amphiphilic species, which provides an efficient and straightforward access to spiroketals and spiroaminals with excellent enantioselectivities. Moreover, racemic 2-(1-hydroxyallyl)anilines were also suitable in this reaction along with a kinetic resolution process, affording enantioenriched spiroaminals and 2-(1-hydroxyallyl)anilines in good yields. The synthetic utility of this method has been demonstrated by efficient enantioselective synthesis of the analogue of Paecilospirone.
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Affiliation(s)
- Wu-Lin Yang
- Shanghai Key Laboratory of Chemical Biology & School of Pharmacy, East China University of Science and Technology, 130 Meilong Road, Shanghai, 200237, P. R. China
| | - Xin-Yu Shang
- Shanghai Key Laboratory of Chemical Biology & School of Pharmacy, East China University of Science and Technology, 130 Meilong Road, Shanghai, 200237, P. R. China
| | - Xiaoyan Luo
- Shanghai Key Laboratory of Chemical Biology & School of Pharmacy, East China University of Science and Technology, 130 Meilong Road, Shanghai, 200237, P. R. China
| | - Wei-Ping Deng
- Shanghai Key Laboratory of Chemical Biology & School of Pharmacy, East China University of Science and Technology, 130 Meilong Road, Shanghai, 200237, P. R. China.,Key Laboratory of the Ministry of Education for Advanced Catalysis Materials, Department of Chemistry, Zhejiang Normal University, Jinhua, 321004, P. R. China
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12
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Xiong Q, Lu J, Shi L, Ran GY. Pd-Catalyzed Tandem [5 + 2] Cycloaddition/Ring Contraction of Phthalide-Derived Alkenes and Vinylethylene Carbonates for the Construction of Benzo-[5,5]-spiroketal Lactones. Org Lett 2022; 24:3363-3367. [DOI: 10.1021/acs.orglett.2c01114] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Qiang Xiong
- Department of Medicinal Chemistry, College of Pharmacy, Chongqing Medical University, Chongqing 400016, China
| | - Ji Lu
- College of Pharmacy, Southwest Medical University, Luzhou 646000, China
| | - Liu Shi
- Department of Medicinal Chemistry, College of Pharmacy, Chongqing Medical University, Chongqing 400016, China
| | - Guang-Yao Ran
- Department of Medicinal Chemistry, College of Pharmacy, Chongqing Medical University, Chongqing 400016, China
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13
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Yang WL, Shang XY, Luo X, Deng WP. Enantioselective Synthesis of Spiroketals and Spiroaminals via Gold and Iridium Sequential Catalysis. Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202203661] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Affiliation(s)
- Wu-Lin Yang
- East China University of Science and Technology School of Pharmacy 130 Meilong Road 200237 Shanghai CHINA
| | - Xin-Yu Shang
- East China University of Science and Technology School of Pharmacy CHINA
| | - Xiaoyan Luo
- East China University of Science and Technology School of Pharmacy CHINA
| | - Wei-Ping Deng
- East China University of Science and Technology School of Pharmacy CHINA
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14
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Mankad Y, Thorat SS, Das P, Rama Krishna G, Kontham R, Reddy DS. Ready Access to Benzannulated [5,5]-Oxaspirolactones Using Au(III)-Catalyzed Cascade Cyclizations. J Org Chem 2022; 87:3025-3041. [PMID: 35188770 DOI: 10.1021/acs.joc.1c02843] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
This work showcases an unprecedented Au(III)-catalyzed cascade cyclization of 2-(4-hydroxyalkynyl)benzoates to access benzannulated [5,5]-oxaspirolactones related to biologically active natural products. This reaction proceeds through an initial 5-endo-dig mode of hydroalkoxylation of the alkynol segment to give the oxocarbenium species (via cyclic enol-ether) followed by the addition of carboxylate onto the oxocarbenium that delivers the oxaspirolactone scaffold. While testing this method's scope, we found that the steric and electronic environment of the hydroxyl group could alter the reaction pathway that delivers isochromenone through a competitive 6-endo-dig mode of attack of the carboxylate onto the tethered alkyne.
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Affiliation(s)
- Yash Mankad
- Natural Products and Medicinal Chemistry Division, CSIR-Indian Institute of Integrative Medicine, Canal Road, Jammu-180001, India.,Organic Chemistry Division, CSIR-National Chemical Laboratory, Dr. Homi Bhabha Road, Pune-411008, India.,Academy of Scientific and Innovative Research (AcSIR), Ghaziabad-201002, India
| | - Sagar S Thorat
- Organic Chemistry Division, CSIR-National Chemical Laboratory, Dr. Homi Bhabha Road, Pune-411008, India.,Academy of Scientific and Innovative Research (AcSIR), Ghaziabad-201002, India
| | - Pronay Das
- Organic Chemistry Division, CSIR-National Chemical Laboratory, Dr. Homi Bhabha Road, Pune-411008, India.,Academy of Scientific and Innovative Research (AcSIR), Ghaziabad-201002, India
| | - Gamidi Rama Krishna
- Organic Chemistry Division, CSIR-National Chemical Laboratory, Dr. Homi Bhabha Road, Pune-411008, India.,Center for Materials Characterization, CSIR-National Chemical Laboratory, Dr. Homi Bhabha Road, Pune-411008, India
| | - Ravindar Kontham
- Organic Chemistry Division, CSIR-National Chemical Laboratory, Dr. Homi Bhabha Road, Pune-411008, India.,Academy of Scientific and Innovative Research (AcSIR), Ghaziabad-201002, India
| | - D Srinivasa Reddy
- Natural Products and Medicinal Chemistry Division, CSIR-Indian Institute of Integrative Medicine, Canal Road, Jammu-180001, India.,Organic Chemistry Division, CSIR-National Chemical Laboratory, Dr. Homi Bhabha Road, Pune-411008, India.,Academy of Scientific and Innovative Research (AcSIR), Ghaziabad-201002, India
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15
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Kataria P, Nomula R, Kontham R. Studies directed toward the synthesis of hedycoropyrans: total synthesis of des-hydroxy (-)-hedycoropyran B ( ent-rhoiptelol B). Org Biomol Chem 2022; 20:444-463. [PMID: 34904991 DOI: 10.1039/d1ob01972d] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
A full account of our efforts directed towards the synthesis of the diarylheptanoid-derived natural products hedycoropyrans that led to the total synthesis of ent-rhoiptelol B is described. In this endeavor, we have attempted two distinct synthetic strategies to access hedycoropyrans A and B, which led us to establish a facile synthetic route for des-hydroxy (-)-hedycoropyran B (ent-rhoiptelol B) from simple and readily accessible building blocks of 4-allylanisole and vanillin, employing Sharpless asymmetric epoxidation, CBS reduction, and an intramolecular AgOTf-catalyzed oxa-Michael reaction of suitably functionalized hydroxy-ynone as key transformations. The investigations disclosed herein will provide insights into designing novel synthetic routes for THP-DAH-derived natural products.
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Affiliation(s)
- Priyanka Kataria
- Organic Chemistry Division, CSIR-National Chemical Laboratory, Dr. Homi Bhabha Road, Pune-411008, India. .,Academy of Scientific and Innovative Research (AcSIR), Ghaziabad-201002, India
| | - Rajesh Nomula
- Organic Chemistry Division, CSIR-National Chemical Laboratory, Dr. Homi Bhabha Road, Pune-411008, India.
| | - Ravindar Kontham
- Organic Chemistry Division, CSIR-National Chemical Laboratory, Dr. Homi Bhabha Road, Pune-411008, India. .,Academy of Scientific and Innovative Research (AcSIR), Ghaziabad-201002, India
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16
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Nakate AK, Thorat SS, Jain S, Rama Krishna G, Vanka K, Kontham R. A silver-catalyzed [3 + 3]-annulation cascade of alkynyl alcohols and α,β-unsaturated ketones for the regioselective assembly of chromanes. Org Chem Front 2022. [DOI: 10.1039/d1qo01643a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
An unprecedented Ag(i)-catalyzed [3 + 3]-annulation of alkynyl alcohols (5-hexyn-1-ols) and α,β-unsaturated ketones is reported to construct simple to complex chromanes.
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Affiliation(s)
- Ashwini K. Nakate
- Organic Chemistry Division, CSIR-National Chemical Laboratory, Dr Homi Bhabha Road, Pune-411008, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad-201002, India
| | - Sagar S. Thorat
- Organic Chemistry Division, CSIR-National Chemical Laboratory, Dr Homi Bhabha Road, Pune-411008, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad-201002, India
| | - Shailja Jain
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad-201002, India
- Physical and Materials Chemistry Division, CSIR-National Chemical Laboratory, Dr Homi Bhabha Road, Pune-411008, India
| | - Gamidi Rama Krishna
- Centre for Materials Characterization, CSIR-National Chemical Laboratory, Dr Homi Bhabha Road, Pune-411008, India
| | - Kumar Vanka
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad-201002, India
- Physical and Materials Chemistry Division, CSIR-National Chemical Laboratory, Dr Homi Bhabha Road, Pune-411008, India
| | - Ravindar Kontham
- Organic Chemistry Division, CSIR-National Chemical Laboratory, Dr Homi Bhabha Road, Pune-411008, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad-201002, India
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17
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Nassar Y, Piva O. Photoredox-catalyzed hydroxymethylation of β-ketoesters: application to the synthesis of [3.3.3] propellane lactones. Org Biomol Chem 2021; 19:9251-9259. [PMID: 34664603 DOI: 10.1039/d1ob01712h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Photoredox-catalysed hydroxymethylation of β-ketoesters substituted by an allyl subunit on the α-position afforded directly the corresponding bicyclic lactones possessing both a hydroxy group and an unsaturation. A subsequent regioselective iodoetherification led to the formation of original [3.3.3] propellane structures. Substitution of the iodine atom by various nucleophiles afforded highly functionnalized structures including triazolomethyl derivatives.
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Affiliation(s)
- Youssef Nassar
- Université de Lyon; CNRS; UCBL; UMR 5246 - Institut de Chimie et de Biochimie Moléculaires et Supramoléculaires, 43, Boulevard du 11 Novembre 1918-69622, Villeurbanne, France.
| | - Olivier Piva
- Université de Lyon; CNRS; UCBL; UMR 5246 - Institut de Chimie et de Biochimie Moléculaires et Supramoléculaires, 43, Boulevard du 11 Novembre 1918-69622, Villeurbanne, France.
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18
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Thorat SS, Rama Krishna G, Kontham R. Stereoselective Total Synthesis of (±)-Pleurospiroketals A and B. J Org Chem 2021; 86:13572-13582. [PMID: 34547199 DOI: 10.1021/acs.joc.1c01634] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A full account of our efforts toward the stereoselective total synthesis of sesquiterpenoid-derived natural products (±)-pleurospiroketals A and B is described. Commercially available 3-methyl-2-cyclohexenone and 2,2-dimethyloxirane were used as key building blocks, and the substrate-controlled stereoselection was exploited to access the entire stereochemistry of these natural products. Initially, a planned synthetic route involving a [6,5]-bicyclic lactone intermediate was found to be insurmountable, and the later strategy comprising OsO4-NMO-mediated dihydroxylation of 3-methyl-2-cyclohexenone, followed by Luche reduction, Eschenmoser methylenation, and Brønsted acid-induced spiroketalization steps, was ultimately identified as the reliable strategy.
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Affiliation(s)
- Sagar S Thorat
- Organic Chemistry Division, CSIR-National Chemical Laboratory, Dr. Homi Bhabha Road, Pune, 411008, India.,Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201002, India
| | - Gamidi Rama Krishna
- Centre for Materials Characterization, CSIR-National Chemical Laboratory, Dr. Homi Bhabha Road, Pune, 411008, India
| | - Ravindar Kontham
- Organic Chemistry Division, CSIR-National Chemical Laboratory, Dr. Homi Bhabha Road, Pune, 411008, India.,Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201002, India
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19
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Affiliation(s)
- Santosh K. Nanda
- Department of chemistry School of Applied Science Centurion University of Technology and Management Paralakhemundi Odisha 761211 India
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20
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Lin X, Liu X, Wang K, Li Q, Liu Y, Li C. Biomimetic approach to the catalytic enantioselective synthesis of tetracyclic isochroman. Nat Commun 2021; 12:4958. [PMID: 34400633 PMCID: PMC8368254 DOI: 10.1038/s41467-021-25198-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2021] [Accepted: 07/22/2021] [Indexed: 11/25/2022] Open
Abstract
Polyketide oligomers containing the structure of tetracyclic isochroman comprise a large class of natural products with diverse activity. However, a general and stereoselective method towards the rapid construction of this structure remains challenging due to the inherent instability and complex stereochemistry of polyketide. By mimicking the biosynthetic pathway of this structurally diverse set of natural products, we herein develop an asymmetric hetero-Diels–Alder reaction of in-situ generated isochromene and ortho-quinonemethide. A broad range of tetracyclic isochroman frameworks are prepared in good yields and excellent stereoinduction (up to 95% ee) from readily available α-propargyl benzyl alcohols and 2-(hydroxylmethyl) phenols under mild conditions. This direct enantioselective cascade reaction is achieved by a Au(I)/chiral Sc(III) bimetallic catalytic system. Experimental studies indicate that the key hetero-Diels-Alder reaction involves a stepwise pathway, and the steric hindrance between in-situ generated isochromene and t-Bu group of Sc(III)/N,N’-dioxide complex is responsible for the enantioselectivity in the hetero-Diels–Alder reaction step. General and stereoselective synthesis of tetracyclic isochroman-containing polyketide oligomers is challenging. Here, the authors report on an Au(I)/chiral Sc(III) bimetallic catalyst for a biomimetic asymmetric hetero-Diels–Alder reaction for in-situ generation of isochromene and ortho-quinonemethide.
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Affiliation(s)
- Xiangfeng Lin
- State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Xianghui Liu
- State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Kai Wang
- State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Qian Li
- State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Yan Liu
- State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, China.
| | - Can Li
- State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, China.
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21
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Zhao B, Zhang Z, Li P, Miao T, Wang L. Synthesis of Spirolactones via a BF 3·Et 2O-Promoted Cascade Annulation of α-Keto Acids and 1,3-Enynes. Org Lett 2021; 23:5698-5702. [PMID: 34264080 DOI: 10.1021/acs.orglett.1c01827] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A novel and effective method for the synthesis of spirolactones from readily available α-keto acids and 1,3-enynes is developed via a BF3·Et2O-promoted cascade annulation. This sequential process is conducted at room temperature, and it provides the functionalized spirolactones in good to excellent yield under metal-free conditions.
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Affiliation(s)
- Beibei Zhao
- Department of Chemistry, Key Laboratory of Green and Precise Synthetic Chemistry, Ministry of Education, Huaibei Normal University, Huaibei, Anhui 235000, P. R. China
| | - Zhen Zhang
- Department of Chemistry, Key Laboratory of Green and Precise Synthetic Chemistry, Ministry of Education, Huaibei Normal University, Huaibei, Anhui 235000, P. R. China
| | - Pinhua Li
- Department of Chemistry, Key Laboratory of Green and Precise Synthetic Chemistry, Ministry of Education, Huaibei Normal University, Huaibei, Anhui 235000, P. R. China
| | - Tao Miao
- Department of Chemistry, Key Laboratory of Green and Precise Synthetic Chemistry, Ministry of Education, Huaibei Normal University, Huaibei, Anhui 235000, P. R. China
| | - Lei Wang
- Department of Chemistry, Key Laboratory of Green and Precise Synthetic Chemistry, Ministry of Education, Huaibei Normal University, Huaibei, Anhui 235000, P. R. China.,Advanced Research Institute and Department of Chemistry, Taizhou University, Taizhou, Zhejiang 318000, P. R. China.,State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai 200032, P. R. China
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22
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Kambale DA, Borade BR, Kontham R. Bismuth(III)-catalyzed bis-cyclization of propargylic diol-esters: a unified approach for the synthesis of [5,5]- and [6,5]-oxaspirolactones. Org Biomol Chem 2021; 19:6618-6622. [PMID: 34264253 DOI: 10.1039/d1ob00974e] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Herein we disclose an unprecedented intramolecular cascade strategy for the construction of α,β-unsaturated [5,5]- and [6,5]-oxaspirolactones that capitalizes on the π-electrophilic Lewis acid-catalyzed 5-exo-dig or 6-exo-dig mode of cyclization of propargylic diol esters, followed by dehydration and spirolactonization steps. Moreover, semi-protected substrates also delivered the respective oxaspirolactones with the same ease and in appreciable yields under optimal reaction conditions.
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Affiliation(s)
- Digambar A Kambale
- Organic Chemistry Division, CSIR-National Chemical Laboratory, Dr. Homi Bhabha Road, Pune-411008, India. and Academy of Scientific and Innovative Research (AcSIR), Ghaziabad-201002, India
| | - Balasaheb R Borade
- Organic Chemistry Division, CSIR-National Chemical Laboratory, Dr. Homi Bhabha Road, Pune-411008, India. and Academy of Scientific and Innovative Research (AcSIR), Ghaziabad-201002, India
| | - Ravindar Kontham
- Organic Chemistry Division, CSIR-National Chemical Laboratory, Dr. Homi Bhabha Road, Pune-411008, India. and Academy of Scientific and Innovative Research (AcSIR), Ghaziabad-201002, India
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23
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Babaahmadi R, Jalali M, Smith JA, Yates BF, Ariafard A. How a Bismuth(III) Catalyst Achieves Greatest Activation of Organic Lewis Bases in a Catalytic Reaction: Insights from DFT Calculations. ChemCatChem 2020. [DOI: 10.1002/cctc.202001688] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Rasool Babaahmadi
- School of Natural Sciences (Chemistry) University of Tasmania Private Bag 75 Hobart TAS 7001 Australia
| | - Mona Jalali
- School of Natural Sciences (Chemistry) University of Tasmania Private Bag 75 Hobart TAS 7001 Australia
| | - Jason A. Smith
- School of Natural Sciences (Chemistry) University of Tasmania Private Bag 75 Hobart TAS 7001 Australia
| | - Brian F. Yates
- School of Natural Sciences (Chemistry) University of Tasmania Private Bag 75 Hobart TAS 7001 Australia
| | - Alireza Ariafard
- School of Natural Sciences (Chemistry) University of Tasmania Private Bag 75 Hobart TAS 7001 Australia
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24
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Borade BR, Dixit R, Kontham R. Total Synthesis of Beshanzuenone D and Its Epimers and Abiespiroside A. Org Lett 2020; 22:8561-8565. [DOI: 10.1021/acs.orglett.0c03157] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- Balasaheb R. Borade
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad-201002, India
| | - Ruchi Dixit
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad-201002, India
| | - Ravindar Kontham
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad-201002, India
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25
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Abstract
Novel access to oxaspiro[n,3,3]propellanes has been developed from bicyclic lactones directly prepared by a photochemical hydroxymethylation or alternatively by a three-step sequence. Thanks to the presence of additional hydroxy- and propargylic groups, a second cyclization catalyzed by silver or bismuth salts, led to the propellane structure which was finally transformed into spiranic derivatives by a Simmons-Smith reaction or condensation with α-ketoesters.
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Affiliation(s)
- Youssef Nassar
- Université de Lyon, Université Claude Bernard Lyon 1, CNRS, INSA Lyon, CPE, Institut de Chimie et de Biochimie Moléculaires et Supramoléculaires (ICBMS), 43, Boulevard du 11 Novembre 1918, 69622 Villeurbanne cedex, France.
| | - Olivier Piva
- Université de Lyon, Université Claude Bernard Lyon 1, CNRS, INSA Lyon, CPE, Institut de Chimie et de Biochimie Moléculaires et Supramoléculaires (ICBMS), 43, Boulevard du 11 Novembre 1918, 69622 Villeurbanne cedex, France.
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26
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Ali S, Gattu R, Singh V, Mondal S, Khan AT, Dubey G, Bharatam PV. Reaction behaviour of arylamines with nitroalkenes in the presence of bismuth(iii) triflate: an easy access to 2,3-dialkylquinolines. Org Biomol Chem 2020; 18:1785-1793. [DOI: 10.1039/c9ob02214g] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
We report the reaction behaviour of arylamines with nitroalkenes in the presence of bismuth(iii) triflate (10 mol%) and diacetoxyiodobenzene (10 mol%).
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Affiliation(s)
- Saghir Ali
- Department of Chemistry
- Indian Institute of Technology Guwahati
- Guwahati-781039
- India
| | - Radhakrishna Gattu
- Department of Chemistry
- Indian Institute of Technology Guwahati
- Guwahati-781039
- India
| | - Varun Singh
- Department of Chemistry
- Indian Institute of Technology Guwahati
- Guwahati-781039
- India
| | - Santa Mondal
- Department of Chemistry
- Indian Institute of Technology Guwahati
- Guwahati-781039
- India
| | - Abu T. Khan
- Department of Chemistry
- Indian Institute of Technology Guwahati
- Guwahati-781039
- India
| | - Gurudutt Dubey
- Department of Medicinal Chemistry
- National Institute of Pharmaceutical Education and Research (NIPER)
- S.A.S. Nagar-160062
- India
| | - P. V. Bharatam
- Department of Medicinal Chemistry
- National Institute of Pharmaceutical Education and Research (NIPER)
- S.A.S. Nagar-160062
- India
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27
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Palange MN, Gonnade RG, Kontham R. TiCl 4-n-Bu 3N-mediated cascade annulation of ketones with α-ketoesters: a facile synthesis of highly substituted fused γ-alkylidene-butenolides. Org Biomol Chem 2019; 17:5749-5759. [PMID: 31124555 DOI: 10.1039/c9ob00649d] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A facile protocol for the synthesis of highly substituted fused γ-alkylidene butenolides using direct annulation of ketones with α-ketoesters, which proceeds through TiCl4-n-Bu3N mediated aldol addition followed by an intramolecular enol-lactonization/cyclization cascade, is reported. Diverse 6-5, 7-5 and 8-5 fused bicyclic γ-ylidene butenolides and highly substituted monocyclic analogs related to biologically relevant natural products were prepared from readily accessible ketone and α-ketoester building blocks. The highly step-economic cascade nature, good substrate scope, easy access to complex products with good to excellent yields, gram-scalability, demonstration of synthetic utility, and unambiguous structural confirmation through X-ray crystallography analyses and analogy are the salient features of this work.
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Affiliation(s)
- Megha N Palange
- Organic Chemistry Division, CSIR-National Chemical Laboratory, Dr. Homi Bhabha Road, Pune-411008, India.
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28
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Borade BR, Nomula R, Gonnade RG, Kontham R. Fe(III)-Catalyzed Diastereoselective Friedel-Crafts Alkylation-Hemiketalization-Lactonization Cascade for the Synthesis of Polycyclic Bridged 2-Chromanol Lactones. Org Lett 2019; 21:2629-2633. [PMID: 30924674 DOI: 10.1021/acs.orglett.9b00614] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
An unprecedented Fe(III)-catalyzed Friedel-Crafts alkylation-hemiketalization-lactonization cascade of electron-rich hydroxy arenes and distinctively functionalized unsaturated 4-keto esters is developed for the construction of polycyclic bridged 2-chromanol lactones. Following this simple and facile protocol, a broad range of products was prepared in good to excellent yields as a single diastereomer. An unusual conglomerate (enantiomerically pure polymorph) of 3ac is reported along with the absolute stereochemistry, and the remaining products were rigorously confirmed by single-crystal X-ray analysis and analogy.
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Affiliation(s)
- Balasaheb R Borade
- Academy of Scientific and Innovative Research (AcSIR) , Ghaziabad 201002 , India
| | | | - Rajesh G Gonnade
- Academy of Scientific and Innovative Research (AcSIR) , Ghaziabad 201002 , India
| | - Ravindar Kontham
- Academy of Scientific and Innovative Research (AcSIR) , Ghaziabad 201002 , India
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29
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Nakate AK, Pratapure MS, Kontham R. Bismuth(iii)-catalyzed cycloisomerization and (hetero)arylation of alkynols: simple access to 2-(hetero)aryl tetrahydrofurans and tetrahydropyrans. Org Biomol Chem 2019; 16:3229-3240. [PMID: 29663001 DOI: 10.1039/c8ob00368h] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
2-(Hetero)aryl tetrahydrofurans and tetrahydropyrans were successfully synthesized using Bi(OTf)3-catalyzed hydroalkoxylation (cycloisomerization) of alkynols (via 5 or 6 exo-dig cyclization) and intermolecular (hetero)arylation. This reaction involves a highly efficient cascade process, where initially the alkynol undergoes a cycloisomerization step via activation of the triple bond and generates the oxocarbenium ion, which subsequently participates in the (hetero)hydroarylation step with electron-rich arenes. Simple to complex suitably functionalized alkynols (4-pentyn-1-ols and 5-hexyn-1-ols) and electron-rich aromatic compounds were found to be reliable substrates in this cascade transformation and furnished a wide range of oxygen heterocycles. This practical tandem process provides a means to build libraries related to pharmacologically active molecules and natural product like scaffolds.
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Affiliation(s)
- Ashwini K Nakate
- Organic Chemistry Division, CSIR-National Chemical Laboratory, Dr Homi Bhabha Road, Pune-411008, India.
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30
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Thorat SS, Kontham R. Recent advances in the synthesis of oxaspirolactones and their application in the total synthesis of related natural products. Org Biomol Chem 2019; 17:7270-7292. [DOI: 10.1039/c9ob01212e] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Oxaspirolactones are ubiquitous structural motifs found in natural products and synthetic molecules with a diverse biochemical and physicochemical profile, and represent a valuable target in natural product chemistry and medicinal chemistry.
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Affiliation(s)
- Sagar S. Thorat
- Organic Chemistry Division
- CSIR-National Chemical Laboratory
- Pune-411008
- India
- Academy of Scientific and Innovative Research (AcSIR)
| | - Ravindar Kontham
- Organic Chemistry Division
- CSIR-National Chemical Laboratory
- Pune-411008
- India
- Academy of Scientific and Innovative Research (AcSIR)
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31
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Thorat SS, Kataria P, Kontham R. 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. Org Lett 2018; 20:872-875. [DOI: 10.1021/acs.orglett.7b04027] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Sagar S. Thorat
- Division
of Organic Chemistry, CSIR-National Chemical Laboratory, Dr. Homi Bhabha Road, Pune-411008, India
- Academy of Scientific
and Innovative Research (AcSIR), New Delhi, India
| | - Priyanka Kataria
- Division
of Organic Chemistry, CSIR-National Chemical Laboratory, Dr. Homi Bhabha Road, Pune-411008, India
- Academy of Scientific
and Innovative Research (AcSIR), New Delhi, India
| | - Ravindar Kontham
- Division
of Organic Chemistry, CSIR-National Chemical Laboratory, Dr. Homi Bhabha Road, Pune-411008, India
- Academy of Scientific
and Innovative Research (AcSIR), New Delhi, India
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32
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Zhu Y, Zhou J, Jin S, Dong H, Guo J, Bai X, Wang Q, Bu Z. Metal-free diastereoselective construction of bridged ketal spirooxindoles via a Michael addition-inspired sequence. Chem Commun (Camb) 2017; 53:11201-11204. [DOI: 10.1039/c7cc05813f] [Citation(s) in RCA: 60] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
A TfOH-catalyzed highly diastereoselective Michael addition/ketalization sequence of 3-hydroxyoxindoles and ortho-hydroxychalcones was developed, leading to biologically important bridged ketal spirooxindoles in moderate to excellent yields.
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Affiliation(s)
- Yanshuo Zhu
- College of Chemistry and Chemical Engineering
- Henan University
- Kaifeng 475004
- China
| | - Jing Zhou
- School of Pharmaceutical Science
- Chongqing Research Center for Pharmaceutical Engineering
- Chongqing Medical University University
- Chongqing 400016
- China
| | - Shaojing Jin
- College of Chemistry and Chemical Engineering
- Henan University
- Kaifeng 475004
- China
| | - Huahui Dong
- College of Chemistry and Chemical Engineering
- Henan University
- Kaifeng 475004
- China
| | - Jiaomei Guo
- College of Chemistry and Chemical Engineering
- Henan University
- Kaifeng 475004
- China
| | - Xuguan Bai
- College of Chemistry and Chemical Engineering
- Henan University
- Kaifeng 475004
- China
| | - Qilin Wang
- College of Chemistry and Chemical Engineering
- Henan University
- Kaifeng 475004
- China
| | - Zhanwei Bu
- College of Chemistry and Chemical Engineering
- Henan University
- Kaifeng 475004
- China
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