- 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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- 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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- 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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