- Synthesis of γ,γ-Disubstituted Butenolides through a Doubly Vinylogous Organocatalytic Cycloaddition
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A novel organocatalytic approach to γ,γ-disubstituted butenolides is described. It is based on a fully site-selective functionalization of 5-alkylidenefuran-2(5H)-ones via trienamine-mediated [4+2]-cycloaddition with α,β,γ,δ-diunsaturated aldehydes. The developed methodology proceeds with excellent stereocontrol and constitutes a unique example of trienamine chemistry with vinylogous dienophiles. Importantly, the reaction has very broad scope and allows for the introduction of substituents also in the α- or the β-position of the butenolide ring. Usefulness of the products obtained has been confirmed in the intramolecular Stetter reaction leading to polycyclic product.
- Skrzyńska, Anna,Drelich, Piotr,Frankowski, Sebastian,Albrecht, ?ukasz
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- Novel bioactive phospholipids: Practical total syntheses of products from the oxidation of arachidonic and linoleic esters of 2-lysophosphatidylcholine
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Total syntheses of nine novel phospholipids were accomplished to facilitate the identification and biological testing of compounds that are generated upon oxidative cleavage of arachidonate and linoleate esters of 2-lysophosphatidylcholine, the two most abundant polyunsaturated phospholipids in low-density lipoprotein. An efficient general synthesis exploiting 2-lithiofuran as a 4-oxo-2butenoyl carbanion equivalent provided phospholipids containing γ-keto-α,β-unsaturated carbonyl functional arrays. By exploiting facile cis-trans isomerizations, two commercially available cis alkenes, (2Z)-2-butene-1,4-diol and 2,5-dihydrofuran, could be employed as starting materials for preparing the Horner-Wadsworth-Emmons reagent 4-(diethoxyphosphoryl)-2E-butenal, a valuable building block for the synthesis of 2,4-dienals. The reagent was exploited in a total synthesis of 13-oxotridec-9E,11E-dienoic acid, confirming the identity of this product that is generated upon autoxidation of linoleic acid and by decomposition of 13-hydroperoxy-9,11-octadecadienoate (13HPODE), especially in the presence of redox active transition metal ions, cytochrome p-450, or hydroperoxide lyase.
- Sun, Mingjiang,Deng, Yijun,Batyreva, Eugenia,Sha, Wei,Salomon, Robert G.
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p. 3575 - 3584
(2007/10/03)
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- New Functionalized Horner-Wadsworth-Emmons Reagents: Useful Building Blocks in the Synthesis of Polyunsaturated Aldehydes. A Short Synthesis of (+/-)-(E,E)-Coriolic Acid
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The new Horner-Wadsworth-Emmons reagents 4 and 5 transform carbonyl compounds into 2,4-pentadienals and 3-methyl-2,4-pentadienals, respectively.Reagent 4 gives good yields of the desired products with a variety of aldehydes and ketones; reagent 5 generally gives good yields with aldehydes, but gives lower yields with ketones.The reactions proceed under mild conditions and give the products as predominantly 2E,4E isomers, with moderate to good stereoselectivity.In general, pure samples of the 2E,4E-dienals can be obtained after chromatography.Reagents 4 have been used in the key step in a short synthesis of (+/-)-13-hydroxy-9(E),11(E)-octadecanoic acid ((E,E)-coriolic aicd, 45).
- Kann, Nina,Rein, Tobias,Akermark, Bjoern,Helquist, Paul
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p. 5312 - 5323
(2007/10/02)
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- Synthesis of Dialkyl (2,3-Epoxy-4-oxoalkyl)phosphonates from (1-Formylalkyl)phosphonates
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Starting with dialkyl (1-formylalkyl)phosphonates 1, the formerly unknown trans-(2,3-epoxy-4-oxoalkyl)phosphonates 5 are obtained on two ways: Compounds with R1 = R2 = H or Me and R3 = alkyl (5b-e and 5k) are prepared in v
- Oehler, Elisabeth,Kang, Heun-Soo,Zbiral, Erich
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p. 299 - 308
(2007/10/02)
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