- 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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- Total synthesis of isoprostanes via the two-component coupling process
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A short total synthesis of isoprostanes has been achieved using a two-component coupling process combined with a diastereoselective protonation under reagent control. The F1-isoprostanes were easily obtained by stereoselective reduction of the C-9 keto group.
- Rodríguez, Ana R.,Spur, Bernd W.
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p. 4575 - 4579
(2007/10/03)
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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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- A highly practical synthesis of natural PGE1,Δ2-trans-PGE1 and 2,2,3,3-tetradehydro-PGE1 via two-component coupling process using zinc-copper reagents
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A highly practical synthesis of natural PGE1,Δ2-trans-PGE1 and 2,2,3,3-tetradehydro-PGE1 has been achieved in which the 1,4-addition reaction of the corresponding functionalized zinc-copper reagents to the enones 2 and/or 4 plays a key role.
- Tsujiyama,Ono,Yoshino,Okamoto,Sato
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p. 4481 - 4484
(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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- Cyclopentanoids from Phenol. VI Chiral Prostanoid Intermediates
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(4S)-4-(t-Butyldimethylsilyloxy)-3-chlorocyclopent-2-enone (3a) is prepared from phenol in five steps including resolution of the initial ring-contraction product, (1RS,4RS)-3,5,5-trichloro-1,4-dihydroxycyclopent-2-ene-1-carboxylic acid .Conjugate addition-elimination reactions of functionalized alylmagnesiocuprate reagents with the synthon (3a) lead to 3-substituted (4S)-4-hydroxycyclopent-2-enone derivatives, and thence by stereospecific transposition of the ring oxygen functions to 2-substituted (4R)-4-hydroxycyclopent-2-nones.The efficiency and versatility of the route are demonstrated by synthesis of the (4R)-2-(6-methoxycarbonylhexyl)- and (4R)-2-(7-hydroxyheptyl)-4-hydroxycyclopent-2-enone derivatives, (5b) and (6b) respectively, which are important intermediates in prostaglandin and prostanoid synthesis.
- Gill, Melvyn,Rickards, Rodney W.
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p. 1063 - 1071
(2007/10/02)
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- Processes for stereospecifically preparing chiral 2-substituted-4-hydroxy-2-cyclopenten-1-one
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A method for stereospecifically preparing chiral 2-substituted-4-hydroxy-2-cyclopenten-1-one which comprises asymmetrically reducing 2-substituted cyclopentane-1,3,4-trione to the corresponding 2-substituted-4(R)-hydroxy-cyclopentane-1,3-dione, enolizing the said dione to obtain the enol ester or enol ether configuration, reducing the enol ester or ether and recovering the desired compound. The chiral 2-substituted-4-hydroxy-2-cyclopenten-1-one are key intermediates in the preparation of prostaglandins.
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