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Showing papers on "Claisen rearrangement published in 1985"




Journal ArticleDOI
TL;DR: In this article, the transposition thermique du chorismate en prephenate suit le meme cours stereochimique que la reaction enzymatique and a lieu par l'intermediaire d'un etat de transition de type choisi
Abstract: La transposition thermique du chorismate en prephenate suit le meme cours stereochimique que la reaction enzymatique et a lieu par l'intermediaire d'un etat de transition de type choisi

76 citations




Journal ArticleDOI
TL;DR: Transposition oxy-Claisen anionique des enolates de potassium, sodium, lithium et silyl enol ether de l'allyloxy-2 propiophenone as discussed by the authors.
Abstract: Transposition oxy-Claisen anionique des enolates de potassium, sodium, lithium et silyl enol ether de l'allyloxy-2 propiophenone

69 citations


Journal ArticleDOI
TL;DR: In this article, the Claisen rearrangements of reactants containing two fluorine atoms in either the allyl or vinyl fragment are described, and the results are shown to be similar to ours.

61 citations


Journal ArticleDOI
TL;DR: In this article, the transposition of alkyl-4 allyl-3 phenethylidene-2 oxazolidines en alkykl-4 benzyl-1' butene-3' yl 2 oxazolines was studied.
Abstract: On etudie la transposition des alkyl-4 allyl-3 phenethylidene-2 oxazolidines en alkyl-4 benzyl-1' butene-3' yl-2 oxazolines-2

51 citations


Journal ArticleDOI
TL;DR: La synthese de la bruceantine(−) pourrait s'effectuer a partir d'un acide oxo-3 perhydronaphtoique.
Abstract: La synthese de la bruceantine(−) pourrait s'effectuer a partir d'un acide oxo-3 perhydronaphtoique

48 citations


Journal ArticleDOI
TL;DR: In this paper, the transposition Claisen du titre resulte d'une deprotonation stereoselective de l'ester pour former l'enolate transposition.
Abstract: La transposition Claisen du titre resulte d'une deprotonation stereoselective de l'ester pour former l'enolate trans

46 citations


Journal ArticleDOI
TL;DR: Synthese des acides methyl-3-, isopropyl-3-pentene-4oiques et methylene-2 cyclohexaneacetique via la transposition de Claisen d'(allyl-3 isoprocessor-4 methylene -2) oxazolidine as mentioned in this paper.
Abstract: Synthese des acides methyl-3-, isopropyl-3-pentene-4oiques et methylene-2 cyclohexaneacetique via la transposition de Claisen d'(allyl-3 isopropyl-4 methylene-2) oxazolidine

Journal ArticleDOI
TL;DR: The monensin spiroketal2, a versatile intermediate for the synthesis of polyether ionophore antibiotics, is prepared from D-fructose as discussed by the authors, where the ester enolate Claisen rearrangement of a glycal propionate, expansion of a furanoid to a pyranoid ring, and acid-catalyzed equilibration of a bicyclic ketal to a spirokal are performed.
Abstract: The monensin spiroketal2, a versatile intermediate for the synthesis of polyether ionophore antibiotics, is prepared from D-fructose. Key steps include the ester enolate Claisen rearrangement of a glycal propionate, expansion of a furanoid to a pyranoid ring, and the acid-catalyzed equilibration of a bicyclic ketal to a spiroketal. An alternative approach, entailing the hetero-Diels-Alder condensation of the exocyclic enol ether 15 with acrolein, is thwarted by facile isomerization to the endocyclic enol ether 18. The complex chemistry and potent biological activity of the polyether antibiotics have engaged widespread i n t e r e ~ t . ~ As ionophores, these compounds possess a striking ability to perturb ionic gradients by catalytically transporting cations across lipid barrier^.^ While optimal membrane and ion selectivity remain elusive goals, the commercial use of monensin for control of poultry coccidiosis6 and enhancement of ruminant feed utilization6 have encouraged intensive efforts in the isolation and study of these compounds. Several have demonstrated potential in human medicine, particularly as cardiovascular agent^.^ In addition to their diverse biological activity, these antibiotics display a formidable molecular complexity, and the attendant challenge of total synthesis has been taken up by numerous research groups.' Structurally, most of the polyether ionophores feature linear chains ( I ) Grateful acknowledgement is made for support of this investigation by a grant from NIH (No. HL-23167). Acknowledgement is also made for the use of the Southern California Regional NMR Facility (National Science Foundation Grant CHE-79-16324). (2) Fellow of Deutscher Akademischer Austausendienst. (3) National Science Foundation Research Fellow, 1981-1984. (4) Westley, J. W., Ed. 'Polyether Antibiotics: Naturally Occurring Acid Ionoohores\": Marcel Dekker. Inc.: New York. 1982: Vols. I and 11. ~~ pressman, man, B. C.; Harris, E. J.; Jagger, W. S.f Johnson, J . M. Proc. Natl. Acad. Sci. U.S.A. 1967, 58, 1949. (6) Ruff, Michael D. In \"Polyether Antibiotics: Naturally Occurring Acid Ionophores\"; Westley, J. W., Ed.; Marcel Dekker, Inc.: New York, 1982; Vol. I , Chapter 6. (7) Hanley, H. G.; Slack, J. D., ref 6, Chapter 8. Reed, P. W.; Bokoch, G. M., ref 6, Chapter 9. Osborne, M. W.; Wenger, J.; Zanko, M.; Kovzelove, F.; Cohen, M. R., ref 6, Chapter IO. (8) (a) Calcimycin: Evans, D. A,; Sacks, C. E.; Kleschick, W. A.; Tabor, T. R. J. Am. Chem. SOC. 1979, 101, 6789-6791. Grieco, P. A,; Williams, E.; Tanaka, H.; Gilman, S. J . Org. Chem. 1980, 45, 3537-3539. (b) Lasalocid A: Nakata, T.; Schmid, G.; Vranesic, B.; Okigawa, M.; Smith-Palmer, T.; Kishi, Y. J . Am. Chem. SOC. 1978, 100,2933-2935. Ireland, R. E.; Anderson, R. C.; Badoud, R.; Fitzsimmons, B. J.; McGarvey, G. J.; Thaisrivongs, S.; Wilcox, C. S. Ibid. 1983, 105, 1988-2006. (c) Monensin: Fukuyama, T.; Akasaka, K.; Karanewsky, D. S.; Wang, C.-L. J.; Schmid, G.; Kishi, Y. Ibid. 1979, 101, 259-263. Still, W. C.; McDonald, J.; Collum, D. Ibid. 1980, 102, 21 17-2121. (d) X-14547A: Nicolaou, K. C.; Papahatjis, D. P.; Claremon, D. A.; Dolle, R. E., 111. Ibid. 1981, 103, 6967-6969. Roush, W. R.; Meyers, A. G. J . Org. Chem. 1981, 46, 1509. Edwards, M. P.; Ley, S. V.; Lister, S. G. Tetrahedron Lett. 1981, 361. (e) Narasin: Kishi, Y. Aldrichim. Acta 1980, 13, 23-30. (f) Salinomycin: Kishi, Y.; Hatakeyama, S.; Lewis, M. D. Front. Chem., Plenary Keynote Lect. IUFAC Congr., 28th 1981 (Pub. 1982), 287-304. Laidler, K. J., Ed., Pergamon: Oxford, U.K. (g) General Methods: Walba, D. M.; Stoudt, G. S. Tetrahedron Lett. 1982, 727-730. Amouroux, R.; Folefoc, G.; Chastrette, F.; Chastrette, M. Tetrahedron Lett. 1981, 2259. Walba, D. M.; Wand, M. P. Tetrahedron Lett. 1982, 4995-4998. (h) Reviews: Kishi, Y. In 'Polyether Antibiotics: Naturally Occurring Acid Ionophores\"; Westley, J. W., Ed.; Marcel Dekker, Inc.: New York, 1982; Vol. 11, Chapter 1. Wierenga, W. In \"The Total Synthesis of Natural Products\"; ApSimon, J., Ed.; Wiley: New York, 1981; Vol. IV, p 263q. 0002-786318511507-327 1$01.50/0 of substituted tetrahydropyran and tetrahydrofuran rings. Comparison reveals that nearly a l l these rings recur with high frequency, often in stereochemically indistinguishable sequences. The unified biosynthetic pathway proposed by Cane , Celmer, and Westley underscores the structural identities and combinatorial diversity of these antibiotics.' We have recently developed a versatile, building-block approach to the polyethers in which prefabricated tetrahydrofuran and tetrahydrogen rings are joined via the ester enolate Claisen rearrangement. This work has culminated in the total synthesis of lasalocid Agb and its enantiomerL0 from readily available carbohydrates. In this and the following two papers in this issue, we report the preparation of several additional subunits for the synthesis of naturally occurring polyethers and potentially informative analogues. Serving as rigid bands in the polyether backbone, spiroketals play a critical role in establishing the coordination geometry necessary for ion complexation.\" Since one of the spiro oxygens usually acts as a ligand as well, spiroketals are prominent features of the polyether class.I2 Monensin's13 spiroketal is a particularly a t t ract ive synthetic target, as it occurs in at least eight other ionophores. Disconnection of the C2,3 and C12,13 bonds of monensin generates the common structural subunit 2, and the results of an aldol and ester enolate Claisen transform are shown in Scheme I. Our synthetic plan for this pol yether building block developed out of model studies which demonstrated the value of the hetero-Diels-Alder condensation in the construction of spiroketals (Scheme II).I4 Although the rigidity of the spiroketal system itself can mediate control of relative s t e r e ~ c h e m i s t r y , ' ~ in this (9) Crane, D. E.; Celmer, W. D.; Westley, J. W. J . Am. Chem. SOC. 1983, (10) Ireland, R. E.; Courtney, L.; Fitzsimmons, B. J. J . Org. Chem., 1983, ( 1 1) Dobler, M. \"Ionophores and Their Structures\"; Wiley: New York, 105, 3594-3600.

Journal ArticleDOI
TL;DR: In this article, the Claisen rearrangement of trifluoromethylated propargylic and allylic alcohols was used to obtain the dienamide.


Journal ArticleDOI
TL;DR: In this article, allyl vinyl sulfures en leurs sulfoxydes correspondants conduit a acceleration remarquable de la vitesse de processus sigmatrope [3+3], conduisant a des sulfines isolables pouvant etre converties en les composes carbonyles dans des conditions douces.
Abstract: L'oxydation des allyl vinyl sulfures en leurs sulfoxydes correspondants conduit a une acceleration remarquable de la vitesse de processus sigmatrope [3+3], conduisant a des sulfines isolables pouvant etre converties en les composes carbonyles dans des conditions douces


Journal ArticleDOI
TL;DR: In this article, the transposition thermique des sels monosodiques d'allyloxy-3 crotonates obtenus a partir d'alcools allyliques primaires ou secondaires, and des sel disodiques de acides allyloxy 3 alcene-2oiques donne les cetones homoallyliques.
Abstract: La transposition thermique des sels monosodiques d'allyloxy-3 crotonates obtenus a partir d'alcools allyliques primaires ou secondaires et des sels disodiques d'acides allyloxy-3 alcene-2oiques donne les cetones homoallyliques


Journal ArticleDOI
TL;DR: The transposition allylique regioselective S→N se fait en N1 de facon predominante; la presence d'un substituant en 6 inverse la selectivite et on obtient des derives N3-allyl as discussed by the authors.
Abstract: La transposition allylique regioselective S→N se fait en N1 de facon predominante; la presence d'un substituant en 6 inverse la selectivite et on obtient des derives N3-allyl

Journal ArticleDOI
TL;DR: In this paper, collision-induced dissociation spectra were used to verify the structures of the daughter ions and a mechanism for the ethene loss was proposed, together with other evidence of acid-induced ortho rearrangement.
Abstract: Molecular protonated ions of allyl phenyl ether undergo a Claisen rearrangement both in the ion source and along the flight path. The rearranged ions undergo fragmentation, the predominat loss being ethene, and only a small contribution from loss of carbon monoxide is observed. Collision-induced dissociation spectra are used to verify the structures of the daughter ions. These spectra, together with other evidence of an acid-induced ortho rearrangement, allow a mechanism to be proposed for the ethene loss. In contrast, molecular protonated ions of propargyl phenyl ether lose exclusively carbon monoxide.

Journal ArticleDOI
TL;DR: Les sels derives de l'alkylation de propionamides ou des fluoroacetamides par le triflate de methyle ou le sulfate de dimethyle reagissent avec un alcoolate de Li derive du cis- ou trans-butene-2ol-1 pour donner directement le produit de transposition sigmatrope 3,3 des N,O-ceteneacetals correspondants.
Abstract: Les sels derives de l'alkylation de propionamides ou des fluoroacetamides par le triflate de methyle ou le sulfate de dimethyle reagissent avec un alcoolate de Li derive du cis- ou trans-butene-2ol-1 pour donner directement le produit de transposition sigmatrope 3,3 des N,O-ceteneacetals correspondants

Journal ArticleDOI
TL;DR: In this paper, a reversible Claisen rearrangement of 3-(3,3-dimethylallyl)-4-(3-3-dynamically-oxy)quinolin-2-one furnished the alkaloid buchapsine, which readily lost the 1, 1,1-dimethylamine group; a mechanism for the cleavage reaction was proposed.


Journal ArticleDOI
TL;DR: In this paper, an enantioselective synthesis of the tetrahydropyran "left-wing" of the ionophore X-14547A is described, wherein stereoselectively 1,2-carbonyl additions and an oxapyronone-to-dihydroparan enolate Claisen rearrangement are key stereocontrol elements.

Journal ArticleDOI
TL;DR: In this paper, a synthesis of the octahydronaphthalenol portion 12 of the HMG-CoA reductase inhibitor dihydrocompactin was described, where a vinylsilane-terminated polyene cyclization and variants of the Claisen rearrangement provided key elements of regio- and stereocontrol.

Journal ArticleDOI
TL;DR: In this paper, the tetrahedral intermediate has been intercepted during Pd(II)-cycloalkenylation of olefinic enolsilane 1 (R=SiMe2t-Bu).


Journal ArticleDOI
TL;DR: In this article, a new method for annulation of rings onto existing allylic alcohol derivatives is presented, which involves Claisen rearrangement followed by nitrile oxide-olefin cycloaddition.


Journal ArticleDOI
TL;DR: The ortho ester Claisen rearrangement of D-ribo- or L-lyxo- hexofuranose derivative which possesses an allyl alcohol functionality on C-3, proceeds stereoselectively to give a 3-C-dialkylated product.
Abstract: The ortho ester Claisen rearrangement of D-ribo- or L-lyxo- hexofuranose derivative which possesses an allyl alcohol functionality on C-3, proceeds stereoselectively to give a 3-C-dialkylated product. The stereochemistry of a newly introduced quaternary center of the product was unambiguously established by a chemical modification.