- Total syntheses of Prelactone V and Prelactone B
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The total syntheses of natural products Prelactone-V and Prelactone-B have been accomplished by a novel Chiron approach starting from D-glucose. The synthesis involves isopropylidene acetal formation of D-glucose using Poly(4-vinylpyridine) supported iodine as a catalyst, Tebbe olefination, Grignard reaction, Wittig olefination, selective mono deprotection of acetal using PMA/SiO2, hydrogenation and anti-1,3-diol formation are as key steps.
- Raghavendra,Tadiparthi, Krishnaji,Yadav
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- Asymmetric synthesis of chiral δ-lactones containing multiple contiguous stereocenters
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A versatile methodology for the asymmetric synthesis of chiral δ-lactones containing multiple contiguous stereocenters has been developed that relies on a series of Evans' aldol, hydroxyl-directed cyclopropanation, methanolysis, and Hg(II) mediated cyclopropane ring-opening reactions for stereocontrol.
- Peed, Jennifer,Perinan Dominguez, Ignacio,Davies, Iwan R.,Cheeseman, Matt,Taylor, James E.,Kociok-Koehn, Gabriele,Bull, Steven D.
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supporting information; experimental part
p. 3592 - 3595
(2011/09/21)
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- Total asymmetric syntheses of β-hydroxy-δ-lactones via umpolung with sulfur dioxide
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Cyclic stereotriads and stereotetrads of the β-hydroxy-d-lactone type, e.g. prelactonesBandE, commonin polyketides and polypropionates, are prepared via SO2-induced oxyallylations of enoxysilanes with (1E,3Z)-1-(1-phenylethoxy) penta-1,3-dien-3-yl carboxylates. Using (Z)- or (E)-enoxysilanes both 4,5-cis- or 4,5-trans-d-lactones are obtained. Depending on the reduction method applied to the obtained aldol intermediates 5,6-trans or 5,6-cis-derivatives are formed. The d-lactones can be prepared in both their enantiomeric forms depending on the (1R)- or (1S)-configuration of the starting 1-(1-phenylethoxy)penta-1,3- dienes.
- Exner, Claudia J.,Laclef, Sylvain,Poli, Florent,Turks, Maris,Vogel, Pierre
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supporting information; experimental part
p. 840 - 845
(2011/04/16)
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- A convergent route to β-hydroxy δ-lactones through Prins cyclisation as the key step: Synthesis of (+)-prelactones B, C and V
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Reactions of homoallylic alcohols with aldehydes in the presence of acid catalysts gave multisubstituted tetrahydropyrans with the creation of one to three new stereogenic centres in a single-pot process. The utility of this approach is extended to the en
- Yadav,Reddy, M. Sridhar,Prasad
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p. 2133 - 2136
(2007/10/03)
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- A short and efficient synthesis of (+)-prelactone B
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The asymmetric total synthesis of (+)-prelactone B, a biologically important natural β-hydroxy-δ-lactone derivative that contains a 2,3-trans-dialkylpyran ring system, is described. This approach involves the use of a very efficient oxazolidinone-mediated anti-aldol reaction, and a diastereoselective coupling between a ketene silyl acetal with an aldehyde followed by lactonization.
- Dias, Luiz C.,Steil, Leonardo J.,Vasconcelos, Valeria De A.
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p. 147 - 150
(2007/10/03)
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- An efficient synthesis of (+)-prelactone B
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An enantioselective synthesis of (+)-prelactone B 1 has been achieved on a multigram scale starting from a known bicyclic precursor 2. The key feature of the strategy is the generation of 3-stereogenic centres from a single bicyclic precursor, which has b
- Yadav,Reddy, K. Bhaskar,Sabitha
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p. 6475 - 6476
(2007/10/03)
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- Application of sulfur ylide mediated epoxidations in the asymmetric synthesis of β-hydroxy-δ-lactones. Synthesis of a mevinic acid analogue and (+)-prelactone B
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Catalytic and stoichiometric asymmetric sulfur ylide reactions were employed to prepare alkyl-aryl epoxide intermediates in a convergent manner. These epoxides were utilized in efficient syntheses of the mevinic acid analogue 1 and prelactone B. Graphical abstract.
- Aggarwal, Varinder K.,Bae, Imhyuck,Lee, Hee-Yoon
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p. 9725 - 9733
(2007/10/03)
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- Synthesis of (+)-prelactone B
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Radical-mediated opening of a trisubstituted epoxy alcohol using cp2TiCl was followed by diastereoselective reduction of the resulting product with a centrally located methylene group, flanked on both sides by two chiral hydroxyl-bearing carbon
- Chakraborty, Tushar K.,Tapadar, Subhasish
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p. 2541 - 2543
(2007/10/03)
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- Enantioselective Synthesis of γ,δ-Disubstituted β-Hydroxy δ-Lactones from Furans: Synthesis of (+)-Prelactone B and its C-4 Epimer
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A new method for the enantioselective synthesis of γ,δ- disubstituted β-hydroxy δ-lactones (5,6-dialkyl-5,6-dihydropyran-2- ones) is reported and exemplified for (+)-prelactone B and its C-4 epimer. Our approach is based on the ring-enlargement of suitably functionalized optically pure 4-hydroxycyclopentanones, which are readily obtained from chiral 4-hydroxycyclopent-2-enones derived from furans. The procedure is amenable to the large-scale synthesis of the title compounds.
- Csák?, Aurelio G.,Mba, Myriam,Plumet, Joaquín
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p. 2092 - 2094
(2007/10/03)
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- Asymmetric Synthesis of 4,5-Disubstituted 3-Hydroxy δ-Lactones: Prelactone B and Prelactone V
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An efficient asymmetric synthesis of δ-lactones such as prelactone B has been developed. As key steps, the SAMP/RAMP-hydrazone methodology for the synthesis of 2-methylenated 1,3-diols and a homogenous hydrogenation were used.
- Enders, Dieter,Haas, Mareile
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p. 2182 - 2184
(2007/10/03)
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- Synthesis of prelactone B
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Prelactone B (1a) and its isomer 1b are possible products of a truncated avermectin polyketide synthase. In order to make them available as reference compounds they were synthesized in a six-step synthesis with 56% overall yield.
- Hanefeld,Hooper,Staunton
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p. 401 - 403
(2007/10/03)
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