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Palakodety Radha Krishna - One of the best experts on this subject based on the ideXlab platform.
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First Total Synthesis of Jomthonic Acid A
Synlett, 2019Co-Authors: Mohan Dumpala, Batthula Srinivas, Palakodety Radha KrishnaAbstract:A stereoselective total synthesis of jomthonic acid A is described. The key features of the synthetic strategy are a Sharpless asymmetric epoxidation, a Gilmann reagent-induced methylation, a Mitsunobu reaction, a Yamaguchi Esterification, and an O-(benzotriazol-1-yl)-N,N,N′,N′-tetramethyluronium tetrafluoroborate (TBTU)-mediated amide coupling. Jomthonic acid A is an architecturally rare amino acid containing a β-methylphenylalanine residue and a 4-methyl-(2E,4E)-hexa-2,4-dienoate moiety. It shows antidiabetic and antiatherogenic activities when tested against mouse ST-13 preadiopocytes.
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Total synthesis of proposed structure of xylogiblactone B by chiron approach
Tetrahedron Letters, 2014Co-Authors: Palakodety Radha Krishna, Ramesh Kunde, Rajesh Nomula, Kallaganti V. S. RamakrishnaAbstract:Abstract Total synthesis of the proposed structure of xylogiblactone B is described using d -(+)-mannitol, regioselective epoxide ring-opening, Yamaguchi Esterification, and ring-closing metathesis as key steps.
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Formal synthesis of amphidinin B
Tetrahedron, 2013Co-Authors: Palakodety Radha Krishna, Kadimi Anitha, Galla RajuAbstract:An efficient, convergent, and highly stereoselective formal synthesis of amphidinin B (1) is reported herein. In Amphidinin B both C10–C21 (4) and C1–C9 (5) fragments were derived from geraniol 6 and mono-PMB ether of 1,4-butane diol 7 in 19 and 9 steps, respectively. The key steps involved in this synthesis are Sharpless asymmetric epoxidation, Evans aldol, Julia olefination, oxa-Michael, Keck allylation, Mannich reaction, Evans asymmetric alkylation, and Yamaguchi Esterification.
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Total synthesis of decarestrictine I and botryolide B via RCM protocol
Organic & biomolecular chemistry, 2010Co-Authors: Palakodety Radha Krishna, T. Jagannadha RaoAbstract:A convergent stereoselective total synthesis of decarestrictine I (1) and botryolide B (1a) invoking a common synthetic strategy is reported. The key steps are: ring-closing metathesis of epoxy dienoic esters obtained through the Yamaguchi Esterification of their respective intermediates to furnish the respective Z-macrocycles (2 and 2a) which were further extrapolated to their respective targets.
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The first synthesis of a 12-membered macrolide natural product via a RCM protocol: determination of absolute stereochemistry
Tetrahedron: Asymmetry, 2008Co-Authors: Palakodety Radha Krishna, R. SrinivasAbstract:Abstract The first synthesis of (10 S ,12 R )-10-hydroxy-12-methyl-1-oxacyclododecane-2,5-dione and its C12 epimer is reported, thereby assigning the absolute stereochemistry of the natural product. The strategy utilizes a syn selective reduction, Yamaguchi Esterification, and ring-closing metathesis as the key steps.
Debendra K. Mohapatra - One of the best experts on this subject based on the ideXlab platform.
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First asymmetric total synthesis of aspergillide D.
Organic & biomolecular chemistry, 2017Co-Authors: Bighnanshu K. Jena, G. Sudhakar Reddy, Debendra K. MohapatraAbstract:The first asymmetric total synthesis of a 16-membered macrolide, aspergillide D, is described. The chiral centers of the acid are derived from d-ribose and the alcohol subunit from 1,8-octane diol through Sharpless kinetic resolution, respectively. The other key reactions include Yamaguchi Esterification, ring-closing metathesis reaction, and Shiina macrolactonization to construct the fully functionalized macrocycle.
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A Unified Synthetic Strategy for Dendrodolides E, F, G, I, J, and L
Asian Journal of Organic Chemistry, 2015Co-Authors: Debendra K. Mohapatra, D. Prabhakar Reddy, Srinivas Gajula, Karthik Pulluri, J. S. YadavAbstract:A unified synthetic strategy has been developed for the total synthesis of the dendrodolide family, employing Jorgensen asymmetric epoxidation, Keck allylation, Brown allylation, Yamaguchi Esterification, and ring-closing metathesis as key reactions.
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A Carbohydrate-Based Approach for the Total Synthesis of Xyolide
Synlett, 2013Co-Authors: Debendra K. Mohapatra, D. Prabhakar Reddy, Dnyaneshwar S. Karhale, Jhillu S. YadavAbstract:We have achieved a total synthesis of xyolide, a bioactive nonenolide, by following a carbohydrate-based approach starting from d -(–)-ribose. The key reactions involved epoxide opening with a long-chain aliphatic Grignard reagent, Yamaguchi Esterification, and a ring-closing-metathesis reaction. The longest linear sequence was nine steps and the overall yield was 30%.
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Studies directed towards the total synthesis of narbonolide: stereoselective synthesis of the C1–C15 chain
Tetrahedron Letters, 2013Co-Authors: Jhillu S. Yadav, Aala Kavita, Kovvuri V. Raghavendra Rao, Debendra K. MohapatraAbstract:Abstract A stereoselective synthesis of the C1–C15 chain of narbonolide, a 14-membered macrolactone belonging to the pikromycin family of antibiotics is described. The key steps involved in this synthesis are desymmetrization of bicyclic olefin with Brown’s asymmetric hydroboration, Evans aldol reaction, Takai olefination and Yamaguchi Esterification to yield the corresponding ester.
Jhillu S. Yadav - One of the best experts on this subject based on the ideXlab platform.
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Stereoselective Total Synthesis of the Marine Macrolide Sanctolide A
European Journal of Organic Chemistry, 2015Co-Authors: Jhillu S. Yadav, Borra Suresh, Pabbaraja SrihariAbstract:The stereoselective total synthesis of sanctolide A, a 14-membered polyketide-nonribosomal peptide (PK-NRP) hybrid macrolide, was accomplished. Sanctolide A contains a rare N-methyl enamide and 2-hydroxyisovaleric acid functionality embedded into the macrocycle. The synthesis relied on Yamaguchi Esterification and intramolecular dehydrative cyclization reactions to construct the core skeleton of the macrolide. The two key chiral centers were generated by Maruoka's allylation and Noyori's asymmetric ketone reduction reactions. Commercially available, inexpensive 2-hydroxyisovaleric acid and hexanaldehyde were utilized as the raw materials for the total synthesis.
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A Carbohydrate-Based Approach for the Total Synthesis of Xyolide
Synlett, 2013Co-Authors: Debendra K. Mohapatra, D. Prabhakar Reddy, Dnyaneshwar S. Karhale, Jhillu S. YadavAbstract:We have achieved a total synthesis of xyolide, a bioactive nonenolide, by following a carbohydrate-based approach starting from d -(–)-ribose. The key reactions involved epoxide opening with a long-chain aliphatic Grignard reagent, Yamaguchi Esterification, and a ring-closing-metathesis reaction. The longest linear sequence was nine steps and the overall yield was 30%.
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Studies directed towards the total synthesis of narbonolide: stereoselective synthesis of the C1–C15 chain
Tetrahedron Letters, 2013Co-Authors: Jhillu S. Yadav, Aala Kavita, Kovvuri V. Raghavendra Rao, Debendra K. MohapatraAbstract:Abstract A stereoselective synthesis of the C1–C15 chain of narbonolide, a 14-membered macrolactone belonging to the pikromycin family of antibiotics is described. The key steps involved in this synthesis are desymmetrization of bicyclic olefin with Brown’s asymmetric hydroboration, Evans aldol reaction, Takai olefination and Yamaguchi Esterification to yield the corresponding ester.
Krishna P. Kaliappan - One of the best experts on this subject based on the ideXlab platform.
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Synthetic studies on palmerolide C: synthesis of an advanced intermediate towards the revised structure of palmerolide C
Organic & biomolecular chemistry, 2020Co-Authors: Ashik A. Sayyad, Khushboo Kaim, Krishna P. KaliappanAbstract:A stereoselective synthesis of the highly advanced intermediates towards the revised structure of palmerolide C and 10-epi-palmerolide C is described in this paper. The required key fragments C1-C6, C7-C14 and C15-C23 have been successfully assembled in a convergent manner to access the C1-C23 framework bearing all the five stereocenters present in the natural product. The synthesis involves the Julia-Kocienski reaction, Yamaguchi Esterification, Takai olefination and regioselective epoxide opening as key steps. The proposed route is flexible and could also be applied to the synthesis of structurally related palmerolides.
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A Shimizu Non‐Aldol Approach to the Formal Total Synthesis of Palmerolide A
Chemistry an Asian journal, 2011Co-Authors: Sandip A. Pujari, Parthasarathy Gowrisankar, Krishna P. KaliappanAbstract:A formal total synthesis of palmerolide A has been accomplished by assembling three fragments by means of successive Julia-Kocienski olefination, Yamaguchi Esterification, and ring-closing metathesis (RCM). Our initial efforts to combine the first two fragments through a Julia-Kocienski reaction between a secondary sulfone and a ketone were not successful; nevertheless, it was feasible between a primary sulfone and aldehyde. Yamaguchi Esterification with the third fragment then set the stage for a RCM reaction. Initial failure of the RCM with a PMB-ether adjacent to the olefins and the difficulty in cleaving the PMB-ether prompted us to change the choice of protecting groups, which then paved the way to the macrocyclic core of palmerolide A.
Biswanath Das - One of the best experts on this subject based on the ideXlab platform.
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A Stereoselective Total Synthesis of Xyolide, a Natural Bioactive Nonenolide
Helvetica Chimica Acta, 2015Co-Authors: Lingaiah Maram, Biswanath DasAbstract:A stereoselective total synthesis of xyolide, a naturally occurring bioactive nonenolide, has been accomplished. The acid fragment of the molecule has been prepared from D-mannitol and the alcohol fragment from (2Z)-but-2-ene-1,4-diol. The synthesis involves the coupling of these two fragments using the Yamaguchi Esterification protocol, followed by intramolecular ring-closing methathesis. The diastereoisomeric alcohol fragment has also been utilized in this synthesis by employing the Mitsunobu Esterification.
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Stereoselective total synthesis and cytotoxic evaluation of C-9 epimers of herbarumin-II and its C-2 epimer ☆
Tetrahedron Letters, 2015Co-Authors: Lingaiah Maram, C. Ganesh Kumar, Yedla Poornachandra, Biswanath DasAbstract:Abstract The total synthesis and cytotoxic evaluation of C-9 epimers of herbarumin-II and its C-2 epimer are described for the first time. The key transformations of the synthesis include Wittig olefination, MacMillan α-hydroxylation, Pinnick oxidation, Yamaguchi Esterification, and intramolecular ring closing metathesis.
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Stereoselective Total Synthesis of Pinolide and Its C2 Epimer and Evaluation of Their Cytotoxic Activity
Synthesis, 2014Co-Authors: Paramesh Jangili, C. Ganesh Kumar, Yedla Poornachandra, Biswanath DasAbstract:Pinolide, a naturally occurring nonenolide and its C2 epimer have been synthesized using d -mannitol and 1,2-epoxyhex-5-ene as the starting materials. The synthesis involves the Jacobsen’s hydrolytic kinetic resolution, Yamaguchi Esterification, and intramolecular ring-closing metathesis as the key steps. The 2- epi -pinolide, the C2 epimer of pinolide, has been synthesized for the first time. The cytotoxic activity of the pinolide and 2- epi -pinolide has been studied.