- A stereoselective approach to optically active butenolides by Horner-Wadsworth-Emmons olefination reaction of α-hydroxy ketones
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Di- and trisubstituted butenolides and tricyclic unsaturated lactones, of high enantiomeric excess were prepared via the efficient sequential esterification Horner-Wadsworth-Emmons reaction of enantiomerically enriched 2-hydroxy-substituted phenones and a
- Krawczyk, Ewa,Koprowski, Marek,Luczak, Jerzy
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- Stereoselective preparation of highly functionalized (Z)-3-magnesiated enoates by an iodine - Magnesium exchange reaction
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3-Iodoenoates are converted into the corresponding alkenylmagnesium species with complete retention of configuration of the double bond; both direct reaction and copper(I)-mediated reactions with various electrophiles provide polyfunctional enoates.
- Sapountzis,Dohle,Knochel
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p. 2068 - 2069
(2007/10/03)
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- Convenient Synthesis of 2,2-Diethoxy-2,5-dihydrofurans, 2(5H)Furanones and 2-Ethoxyfurans. Crystal and Molecular Structure of a Barrelenone Diels-Alder Product
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Reaction of 1,2-hydroxyketones 5 with (2,2-diethoxyvinylidene)triphenylphosphorane (2) or (2,2-diethoxyvinyl)triphenylphosphonium tetrafluoroborates 6 yields the 2,2-diethoxy-2,5-dihydrofurans 9.Depending on the reaction conditions used, the orthoesters 9 can be hydrolized to give 2(5H)furanones 10 and 2-ethoxyfurans 11, respectively. 4,5-Dimethyl-5,6-dihydro-2-pyranone (20) and 8-methoxycoumarin (23) are prepared, starting from (2,2-diethoxyvinyl)triphenylphosphonium tetrafluoroborate (6a) and 1-hydroxy-2-methyl-3-butanone (16) or 2-hydroxy-3-methoxy-benzaldehyde (21).The 2-ethoxyfuranes 11 readily undergo Diels-Alder reactions with 2-chloracrylonitrile (24), maleic anhydride (26), N-phenyl-1,2,4-triazoline-3,5-dione (28) and dimethyl acetylenedicarboxylate (30) to give the corresponding Diels-Alder products 25, 27, 29 and 31, respectively.Contrary to 2-ethoxyfuran 11b, 11a reacts with two equivalents of acetylene 30, to yield barrelenone 34.The structure of 34 unequivocally is established by X-ray structure analysis. - Keywords: 2,2-Diethoxy-2,5-dihydrofurans, 2(5H)Furanones, 2-Ethoxyfurans, Barrelenone, Diels-Alder Products, X-Ray
- Saalfrank, Rolf W.,Hafner, Wieland,Markmann, Joachim,Welch, Andreas,Peters, Karl,Schnering, Hans Georg von
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p. 389 - 406
(2007/10/02)
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- Vinyl Anions. Part 9. Vinyl Carbanions Derived from Acrylic Esters and their β-Phenyl Derivatives
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Ethyl ββ-diphenylacrylate, ethyl cis- and trans-cinnamate, methyl and ethyl maleate, ethyl fumarate, and methyl acrylate were treated with a strong base at low temperatures to yield the derived vinyl carbanions.The vinyl carbanions were treated with vario
- Feit, Ben Ami,Melamed, Uri,Schmidt, Richard R.,Speer, Heike
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p. 1329 - 1338
(2007/10/02)
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