- A Facile, Efficient Synthesis of 2-substituted-4-Hydroxy-2-cyclopenten-1-ones
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A simple procedure for the transformation of 2-substituted 4-bromo-2-cyclopenten-1-ones into the title compounds as well as into the corresponding 4-methoxy derivatives is described.
- Baraldi, P. G.,Pollini, G. P.,Simoni, D.,Zanirato, V.,Barco, A.,Benetti, S.
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- An efficient synthesis of enantiomerically pure (1R,2S,5S)- and (1S,2R,5R)-rosaprostol methyl esters
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We report a concise synthesis of the enantiomerically pure 1,2-trans-1,5-cis-methyl esters of rosaprostol, a prostaglandin derivative used for the treatment of gastric and duodenal ulcers, using as key step the chemo- and stereoselective Michael addition of a Grignard reagent to an unprotected hydroxycyclopentenone. Georg Thieme Verlag Stuttgart.
- Murcia, M. Carmen,De La Herran, Gabriela,Plumet, Joaquín,Csaky, Aurelio G.
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p. 1553 - 1556
(2008/02/05)
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- An efficient asymmetric synthesis of prostaglandin E1
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An asymmetric total synthesis of Prostaglandin E1 (5) has been achieved in a two-component coupling process. The chiral hydroxycyclopentenone 6 was readily available from furan with 96% ee. The key reaction step was a kinetic enzymatic resolution followed by an in situ inversion. A catalytic asymmetric reduction of the γ-iodo vinyl ketone 19 with the Corey CBS catalyst gave the ω-side chain 7 with >96% ee. Conjugate addition using the reaction with dilithiocyanocuprate followed by mild cleavage of the silyl protective groups and enzymatic hydrolysis of the methyl ester 22 gave (-)-PGE1 5 in high yield.
- Rodriguez, Ana,Nomen, Miguel,Spur, Bernd Werner,Godfroid, Jean-Jacques
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p. 2655 - 2662
(2007/10/03)
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- Synthesis of (±)-15-thia-15-deoxy-PGE1 methyl ester
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The 15-thia-15-deoxy analogue of prostaglandin E1 methyl ester has been prepared by the zirconocene chloride mediated conjugate addition of an n-pentyl ethynyl sulfide derived anion to an appropriately substituted cyclopentenone. Similar methodology has also been used to prepare other 3-(3'-thia-1'-octenyl)-cyclopentanones.
- Holland,Ratemi,Contreras
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- 1,4-ADDITION OF SOME NITROALKANES TO 2-(6-METHOXYCARBONYLHEXYL)-4-HYDROXY-2-CYCLOPENTEN-1-ONE
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The 1,4-addition of nitromethane and 1-nitropropane to 2-(6-methoxycarbonylhexyl)-4-hydroxy-2-cyclopenten-1-one under the conditions of the Michael reaction leads to the formation of 2-(6-methoxycarbonylhexyl)-3-nitroalkyl-4-hydroxycyclopentan-1-ones in the form of the trans,trans, trans,cis, cis,trans, and cis,cis isomers.The effect of the 4-OH group on the ratio of the trans,trans ans trans,cis isomers was investigated.The chemical stability of the 2-(6-methoxycarbonylhexyl)-3-nitroalkyl-4-hydroxycyclopentan-1-ones in basic and acidic media was investigated.A general scheme for the reactions of nitroalkanes with 2-(6-methoxycarbonylhexyl)-4-hydroxy-2-cyclopenten-1-one is proposed on the basis of these data.
- Gailite, V. A.,Freimanis, Ya. F.,Turovskii, I. V.,Gavars, M. P.,Ozola, A. Ya.,Dipan, I. V.
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p. 1267 - 1275
(2007/10/02)
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- A New Method of Synthesizing 7-(2-Hydroxy-5-oxo-1-cyclopentenyl)heptanoic Acid and Related Compounds
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A useful prostanoid synthon, 7-(2-hydroxy-5-oxo-1-cyclopentenyl)heptanoic acid (3), was prepared from commercially available cyclooctanone in two steps.Nine other related cyclopentanoids which are also valuable synthons for prostaglandins were obtained from 3 in reasonable yields via several steps.The procedure is capable of generating these synthons on a laboratory scale.
- Naora, Hirokazu,Ohnuki, Takashi,Nakamura, Asao
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p. 2401 - 2404
(2007/10/02)
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- Production of cyclopentenones
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A process for preparing an optically active cyclopentenone of the formula: wherein R is a hydrogen atom or a lower alkyl group and n is an integer of 4 to 8, which comprises contacting a dl-cyclo-pentenone ester of the formula: wherein R and n are each as defined above and R′ is a lower alkyl group optionally substituted with halogen on an enzyme having a capability of hydrolyzing selectively either one of the d- or l-form isomer in the dl-cyclopentenone ester (II) in an aqueous medium for asymmetric hydrolysis.
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- A New Synthesis of 8-(ω-Carbomethoxyhexyl)-11-hydroxycyclopent-8(12)-ene-9-one, a Versatile Prostaglandin Intermediate
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8-(ω-Carbomethoxyhexyl)-11-hydroxycyclopent-8(12)-ene-9-one (V), a versatile prostaglandin synthon, has been synthesised starting from easily accesible undecylenic acid (VI).The synthesis involves preparation of dihydroxy undecanoic acid (IX) and its methyl ester (X), methyl 9-formylnonanoate (XI), the monoester (XII) and the corresponding unsaturated acid (XIII), γ-lactone (XIV), cyclopentenone acid (XV) and finally the all important PG-intermediate 2-(ω-carbomethoxyhexyl)cyclopentenone (IV).Its reduction with sodium borohydride gives the saturated alcohol (XVI), which via oxidation with Jones' reagent and bromination-dehydrobromination sequence could be converted back to IV.However, IV, on reduction with aluminium isopropoxide gives the allylic alcohol (XXIII), which is converted via acetylation into the acetate (XXIV).Subsequent oxidation of acetate (XXIV) with t-butyl chromate yields the keto-acetate (XXV), which on reduction with aluminium isopropoxide furnishes the hydroxy acetates (XXXII).The hydroxyl group in XXXII is protected as tetrahydropyranyloxy derivative (XXXIII).Hydrolysis of XXXIII with alkali leads to the hydroxy acids (XXXIV).Oxidation of XXXIV with Jones' reagent at low temperature for a short period yields the keto-acid (XXXV), which is esterified to give the ester (XXXVI).Finally, removal of the pyranyloxy group from XXXVI furnishes the versatile synthon (V), identical with the sample prepared by a known procedure.
- Thakur, S. B.,Jadhav, K. S.,Bhattacharyya, S. C.
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p. 675 - 683
(2007/10/02)
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- Oxocyclopentenol Syntheses
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Metal-assisted decomposition of α-diazo carbonyl compounds in 1,2-dialkoxy-1-alkenes are shown to yield β,β'-dialkoxycyclopropyl carbonyl systems, whose acid hydrolysis produces α-alkoxy-γ-dicarbonyl substances.Intramolecular condensations of the latter lead to oxocyclopentenols.Application of this reaction scheme to the syntheses of a prostaglandin intermediate and of tetrahydropyrethrolone is described.
- Wenkert, Ernest,Greenberg, Richard S.,Raju, Muppala S.
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p. 4681 - 4685
(2007/10/02)
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- Cyclopentanoids from Phenol. Part 5. Terminally Functionalised 2- and 3-Alkyl-4-hydroxycyclopent-2-enones. A Versatile Approach to Prostanoids
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Terminally functionalised 3-alkyl-4-hydroxycyclopent-2-enones are prepared by conjugate addition-elimination reactions of magnesiocuprate reagents with ethers of 3-chloro-4-hydroxycyclopent-2-enone.The side-chain functionality can be modified either selectivity, or simultaneously with modification of the nucleus.Stereospecific trasposition of the ring-oxygen functions converts these compounds into terminally functionalised 2-alkyl-4-hydroxycyclopent-2-enones which are important intermediates in prostanoid synthesis.Thus the 2-substituted cyclopentenone (2) is prepared in ca. 60percent yield from the 3-chlorocyclopentenone (7), itself available in four steps from phenol.
- Gill, Melvyn,Rickards, Rodney W.
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p. 599 - 606
(2007/10/02)
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- 13-Cis prostaglandin derivatives
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13-Cis prostaglandin derivatives; cis-octenol ether copper(I) lithium reagents and methods of making such reagents and using the reagents to prepare the 13-cis prostaglandin derivatives. The 13-cis prostaglandin derivatives exhibit prostaglandin-like pharmacological properties and are further useful as intermediates for the corresponding prostaglandin isomers having the normal 13-trans configuration.
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- Preparation of prostaglandin precursors
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2-Alkoxy-4-hydroxy-5-oxocyclopent-1-eneheptanoic acid and its lower alkyl esters are reduced with metallic hydrides to yield the corresponding 3-hydroxy-5-oxo-cyclopent-1-eneheptanoic acid and its esters. The latter compounds are valuable intermediates in the preparation of pharmacologically active prostaglandin derivatives.
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