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Kajal Chakraborty - One of the best experts on this subject based on the ideXlab platform.
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First report of substituted 2H-Pyranoids from brown seaweed Turbinaria conoides with antioxidant and anti-inflammatory activities
2019Co-Authors: Kajal Chakraborty, Shubhajit DharaAbstract:The organic extract of Turbinaria conoides, a brown seaweed harvested from the Gulf of Manner region of Indian peninsular was chromatographically fractionated to yield three substituted 2H-Pyranoids, namely methyl-21-yl-[5′, 6′- dihydro-5′-yl-{54-(4-hydroxybenzoyl)-oxy-(52-methylbutyl)}-3′-methyl-2H-Pyran]-21-methyl butanoate (1), 11-[(3′, 6′-dihydro-4′-methyl-2′-oxo-2H-Pyran-3′-yl)methyl]-10-methylhexyl benzoate (2), and [6-ethyl-3,4-dimethyl-(tetrahydro-2′, 2′, 6′-trimethyl-2H-Pyran-3′-yl)-2,5-cycloheptadiene]-1-propanoate (3). The compounds 1 and 2 bearing 2H-Pyranyl-4-hydroxybenzoyl and 2H-Pyranyl-10-methylhexylbenzoate moieties exhibited potential antioxidant activities (IC50 0.54-0.69 mg mL−1) as commercial antioxidant (α-tocopherol IC50 0.63-0.73 mg mL−1). Likewise, potential bioactivity of the 2H-Pyran derivative, 1 against 5-lipoxygenase (IC50 ∼ 1 mg mL−1) along with higher index of selectivity (COX-1 inhibitoryIC50/COX-2 inhibitoryIC50 1.88) indicated their selective anti-inflammatory properties against inducible inflammatory mediators than that displayed by commercially available non-steroidal anti-inflammatory drug (ibuprofen, 0.44). Structure activity relationship analysis of the studied compounds showed that the antioxidative and anti-inflammatory properties were directly proportional to their electronic properties. The previously undescribed 2H-Pyranoids might constitute as potential antioxidative and anti-inflammatory pharmacophores for medicinal applications.
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first report of two new antioxidative meroterpeno 2h pyranoids from short necked yellow foot clam paphia malabarica family veneridae with bioactivity against pro inflammatory cyclooxygenases and lipoxygenase
Natural Product Research, 2017Co-Authors: Minju Joy, Kajal ChakrabortyAbstract:AbstractTwo new meroterpeno 2H-Pyranoids were isolated from the EtOAc:MeOH extract of yellow-foot clam Paphia malabarica. The structures of these newly reported compounds were elucidated based on spectroscopic interpretations. This is the first report of biogenic 2H-Pyrans bearing decadienyl and allyloxy-(isopentanyl)-cyclohexene skeletons from marine biota. The extended C18 sesquiterpenoid with prenylated irregular farnesene framework was characterised as 2-((E)-deca-1,8-dien-10-yl)-11,12-dihydro-13-propyl-2H-Pyran (1). The compound 2, 1′-((10E)-10-(10-(pentan-4-yl)-cyclohex-4-enyl)-allyloxy)-tetrahydro-2′,2′-dimethyl-2H-Pyran represents the first example of naturally occurring C21 prenylated bisabolene-type meroterpenoid, whereas tetrahydro-2′,2′-dimethyl-2H-Pyran remains attached at C-2′ position of rearranged bisabolene framework formed by allyloxy linkage. The antioxidant activities (DPPH/ABTS+) of 1 and 2 were comparable (IC50 < 1.0 mg/mL) with α-tocopherol. In addition, these compounds exhibited gr...
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First report of two new antioxidative meroterpeno 2H-Pyranoids from short-necked yellow-foot clam Paphia malabarica (family: Veneridae) with bioactivity against pro-inflammatory cyclooxygenases and lipoxygenase
2016Co-Authors: Minju Joy, Kajal ChakrabortyAbstract:Two new meroterpeno 2H-Pyranoids were isolated from the EtOAc:MeOH extract of yellow-foot clam Paphia malabarica. The structures of these newly reported compounds were elucidated based on spectroscopic interpretations. This is the first report of biogenic 2H-Pyrans bearing decadienyl and allyloxy-(isopentanyl)-cyclohexene skeletons from marine biota. The extended C18 sesquiterpenoid with prenylated irregular farnesene framework was characterised as 2-((E)-deca-1,8-dien-10-yl)-11,12-dihydro-13-propyl-2H-Pyran (1). The compound 2, 1′-((10E)-10-(10-(pentan-4-yl)-cyclohex-4-enyl)-allyloxy)-tetrahydro-2′,2′-dimethyl-2H-Pyran represents the first example of naturally occurring C21 prenylated bisabolene-type meroterpenoid, whereas tetrahydro-2′,2′-dimethyl-2H-Pyran remains attached at C-2′ position of rearranged bisabolene framework formed by allyloxy linkage. The antioxidant activities (DPPH/ABTS+) of 1 and 2 were comparable (IC50
Minju Joy - One of the best experts on this subject based on the ideXlab platform.
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first report of two new antioxidative meroterpeno 2h pyranoids from short necked yellow foot clam paphia malabarica family veneridae with bioactivity against pro inflammatory cyclooxygenases and lipoxygenase
Natural Product Research, 2017Co-Authors: Minju Joy, Kajal ChakrabortyAbstract:AbstractTwo new meroterpeno 2H-Pyranoids were isolated from the EtOAc:MeOH extract of yellow-foot clam Paphia malabarica. The structures of these newly reported compounds were elucidated based on spectroscopic interpretations. This is the first report of biogenic 2H-Pyrans bearing decadienyl and allyloxy-(isopentanyl)-cyclohexene skeletons from marine biota. The extended C18 sesquiterpenoid with prenylated irregular farnesene framework was characterised as 2-((E)-deca-1,8-dien-10-yl)-11,12-dihydro-13-propyl-2H-Pyran (1). The compound 2, 1′-((10E)-10-(10-(pentan-4-yl)-cyclohex-4-enyl)-allyloxy)-tetrahydro-2′,2′-dimethyl-2H-Pyran represents the first example of naturally occurring C21 prenylated bisabolene-type meroterpenoid, whereas tetrahydro-2′,2′-dimethyl-2H-Pyran remains attached at C-2′ position of rearranged bisabolene framework formed by allyloxy linkage. The antioxidant activities (DPPH/ABTS+) of 1 and 2 were comparable (IC50 < 1.0 mg/mL) with α-tocopherol. In addition, these compounds exhibited gr...
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First report of two new antioxidative meroterpeno 2H-Pyranoids from short-necked yellow-foot clam Paphia malabarica (family: Veneridae) with bioactivity against pro-inflammatory cyclooxygenases and lipoxygenase
2016Co-Authors: Minju Joy, Kajal ChakrabortyAbstract:Two new meroterpeno 2H-Pyranoids were isolated from the EtOAc:MeOH extract of yellow-foot clam Paphia malabarica. The structures of these newly reported compounds were elucidated based on spectroscopic interpretations. This is the first report of biogenic 2H-Pyrans bearing decadienyl and allyloxy-(isopentanyl)-cyclohexene skeletons from marine biota. The extended C18 sesquiterpenoid with prenylated irregular farnesene framework was characterised as 2-((E)-deca-1,8-dien-10-yl)-11,12-dihydro-13-propyl-2H-Pyran (1). The compound 2, 1′-((10E)-10-(10-(pentan-4-yl)-cyclohex-4-enyl)-allyloxy)-tetrahydro-2′,2′-dimethyl-2H-Pyran represents the first example of naturally occurring C21 prenylated bisabolene-type meroterpenoid, whereas tetrahydro-2′,2′-dimethyl-2H-Pyran remains attached at C-2′ position of rearranged bisabolene framework formed by allyloxy linkage. The antioxidant activities (DPPH/ABTS+) of 1 and 2 were comparable (IC50
Pedro O Miranda - One of the best experts on this subject based on the ideXlab platform.
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Direct Access to 2,3,4,6-Tetrasubstituted Tetrahydro‑2H‑pyrans via Tandem SN2′–Prins Cyclization
2017Co-Authors: Jimena Scoccia, Pedro O Miranda, Sixto J. Pérez, Victoria Sinka, Daniel A. Cruz, Juan M. López-soria, Israel Fernández, Víctor S. Martín, Juan I. PadrónAbstract:A new, direct, and diastereoselective synthesis of activated 2,3,4,6-tetrasubstituted tetrahydro-2H-Pyrans is described. In this reaction, iron(III) catalyzed an SN2′–Prins cyclization tandem process leading to the creation of three new stereocenters in one single step. These activated tetrahydro-2H-Pyran units are easily derivatizable through CuAAC conjugations in order to generate multifunctionalized complex molecules. DFT calculations support the in situ SN2′ reaction as a preliminary step in the Prins cyclization
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iron iii catalyzed prins type cyclization using homopropargylic alcohol a method for the synthesis of 2 alkyl 4 halo 5 6 dihydro 2h pyrans
Organic Letters, 2003Co-Authors: Pedro O Miranda, Juan I Padron, Jaime Bermejo, David Díaz Díaz, Víctor S. MartínAbstract:A new Prins-type cyclization between homopropargylic alcohol and aldehydes in the presence of FeX3 to obtain 2-alkyl-4-halo-5,6-dihydro-2H-Pyrans in good yield is described. Osmium-catalyzed cis dihydroxylation provided direct access to trans-2-alkyl-3-hydroxy-tetrahydro-pyran-4-ones. Anhydrous ferric halides are also shown to be excellent catalysts for the standard Prins cyclization using homoallylic alcohol. Isolation of an intermediate acetal provides substantiation of a proposed mechanism.
Prakas R Maulik - One of the best experts on this subject based on the ideXlab platform.
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carbanion induced synthesis of annulated unsymmetrical biaryls through ring transformation of 2h pyran 2 one
Journal of The Chemical Society-perkin Transactions 1, 2002Co-Authors: Nidhi Agarwal, Ashoke Sharon, Abhishek S Saxena, Prakas R MaulikAbstract:An innovative and convenient one-pot synthesis of unsymmetrical macrocyclic biaryls (3, 5 and 8), dibenzo[a,c]cycloheptenes (10), 3,4-dihydro-2(1H)-naphthones (15), tetrahydroisoquinolines (18), dihydro-1H-isothiochromenes (20), benzo[c]thiochromenes (22) and 2,3-dihydro-1-benzothiophenes (24) is described. These compounds are obtained through base-catalyzed ring transformation reactions of suitably functionalized 2H-Pyran-2-ones (1,6) by a carbanion, generated from cycloalkanone (2,4,7), benzosuberone (9), cyclohexanedione monoketal (12), 4-piperidone (17), tetrahydrothiopyran-4-one (19), thiochroman-4-one (21) or tetrahydrothiophene-3-one (23).
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an expeditious synthesis of imidazo 1 2 a pyridines through nucleophile induced ring transformation reactions of 6 aryl 4 methylsulfanyl 2h pyran 2 one 3 carbonitriles
Tetrahedron Letters, 2002Co-Authors: Nidhi Agarwal, Ashoke Sharon, Prakas R MaulikAbstract:An efficient and convenient synthesis of 2-(5-aryl-8-nitro-2,3-dihydroimidazo[1,2-a]pyridin-7(1H)-ylidene)acetonitriles (3) and 6-aryl-4-{2-[(E)-nitromethylidene]-1-imidazolidinyl}-2-oxo-2H-Pyran-3-carbonitriles (4) through nucleophile induced ring transformation of suitably functionalized 2H-Pyran-2-one (1) from imidazoliden-2-ylidene nitromethane is delineated.
Stephen P. Fletcher - One of the best experts on this subject based on the ideXlab platform.
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copper catalysed asymmetric allylic alkylation of alkylzirconocenes to racemic 3 6 dihydro 2h pyrans
Beilstein Journal of Organic Chemistry, 2015Co-Authors: Emeline Rideau, Stephen P. FletcherAbstract:Asymmetric allylic alkylation is a powerful reaction that allows the enantioselective formation of C–C bonds. Here we describe the asymmetric alkylation of alkylzirconium species to racemic 3,6-dihydro-2H-Pyrans. Two systems were examined: 3-chloro-3,6-dihydro-2H-Pyran using linear optimization (45–93% ee, up to 33% yield, 5 examples) and 3,6-dihydro-2H-Pyran-3-yl diethyl phosphate with the assistance of a design of experiments statistical approach (83% ee, 12% yield). 1H NMR spectroscopy was used to gain insight into the reaction mechanisms.
