- An alternative approach to the synthesis of the three fragments of anachelin H
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The synthesis of the fully protected peptide, polyketide and alkaloid fragments of anachelin H is presented. The peptide fragment was prepared using a liquid phase peptide synthesis; the polyketide fragment was synthetized using a cross metathesis and an intramolecular oxa-Michael reaction as the key steps to introduce the desired stereochemistry; finally, the alkaloid fragment was obtained by an oxidative cyclization of a catechol derivative using potassium ferricyanide. The synthesis of all fragments was based on the use of natural amino acids as sources of asymmetry. The independent synthesis of the three fragments should allow more efficient biological studies on the fragments instead of the whole natural product. Experiments to illustrate the coupling of fragments and the effectiveness of the convergent strategy are also described.
- Gamba-Sánchez, Diego,Garzón-Posse, Fabián,Prunet, Jo?lle
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p. 2702 - 2715
(2020/04/17)
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- NUCLEOPHILIC FLUORINATION OF AROMATIC COMPOUNDS
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Iodylbenzene derivatives substituted with electron donating as well as electron withdrawing groups on the aromatic ring are used as precursors in aromatic nucleophilic substitution reactions. The iodyl group (IO2) is regiospecifically substituted by nucleophilic fluoride to provide the corresponding fluoroaryl derivatives. No-carrier-added [F-18] fluoride ion derived from anhydrous [F- 18]KF/Kryptofix, [F-18]CsF or a quaternary ammonium fluoride (e.g., Me4NF, Et4NF, n-Bu4NF, (PhCH2)4NF) exclusively substitutes the iodyl moiety in these derivatives and provides high specific activity F- 18 labeled fluoroaryl analogs. Iodyl derivatives of a benzothiazole analog and 6-iodyl-L-dopa derivatives have been synthesized as precursors and have been used in the preparation of no-carrier-added [F-18]fluorobenzothiazole as well as 6-[F-18]fluoro-L-dopa.
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Page/Page column 24
(2010/04/03)
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- NO-CARRIER-ADDED NUCLEOPHILIC [F-18] FLUORINATION OF AROMATIC COMPOUNDS
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Phenyliodonium ylide derivatives substituted with electron donating as well as electron withdrawing groups on the aromatic ring are shown for use as precursors in aromatic nucleophilic substitution reactions. The iodonium ylide group is substituted by nucleophiles such as halide ions to provide the corresponding haloaryl derivatives. No- carrier-added [F-18]fluoride ion exclusively substitutes the iodonium ylide moiety in these derivatives and provides high specific activity F- 18 labeled fluoro derivatives. Protected L-dopa-6-iodonium ylide derivative have been synthesized as a precursors for the preparation of no-carrier-added 6-[F- 18]fluoro-L-dopa. The iodonium ylide group in this L-dopa.derivative is nucleophilically substituted by no-carrier-added [F-18]fluoride ion to provide a [F-18]fluoro intermediates which upon acid hydrolysis yielded 6-[F- 18]fluoro-L-dopa.
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Page/Page column 18
(2010/11/03)
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- 6-[18F]Fluoro-L-DOPA by radiofluorodestannylation : A short and simple synthesis of a new labelling precursor
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This paper describes a short and simple synthesis of a new fully protected stannylated precursor, namely N-(tert-butoxycarbonyl)-3,4-di(tert-butoxycarbonyloxy)-6-trimethylstannyl-L -phenylalanine ethyl ester, for the preparation of 6-[18F]fluoro-L-DOPA, used routinely in our Positron Emission Tomography program on neurodegenerative diseases as a tracer of the cerebral dopamine metabolism. The chemical pathway described for the total synthesis of our labelling precursor uses a straightforward protection sequence. This 4-step chemical synthesis allows the rapid preparation of several grammes of pure material in good overall yield. Regioselective radiofluorodestannylation using [18F]fluorine ([18F]F2, cyclotron-produced isotope, half-life : 110 min) gave pure 6-[18F]fluoro-L- DOPA (8) in good radiochemical yield (26% decay-corrected, based on starting [18F]fluorine recovered from the target) in 45-50 min after the End of Bombardment. The product was found to be >99% chemically, radiochemically and enantiomerically pure.
- Dolle, Frederic,Demphel, Stephane,Hinnen, Francoise,Fournier, Denis,Vaufrey, Francoise,Crouzel, Christian
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p. 105 - 114
(2007/10/03)
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- L-DOPA ethyl ester to treat Parkinson's disease
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Patients suffering from Parkinson's disease are treated by administering a composition which contains an active ingredient and a pharmaceutically acceptable carrier. The active ingredient comprises L-DOPA ethyl ester in an amount which is at least 97% by weight of the active ingredient and L-DOPA in an amount which is less than 1% by weight of the active ingredient.
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- Process for preparing ethyl ester of L-DOPA
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A composition which comprises a pharmaceutically acceptable carrier and an active ingredient, such active ingredient comprising L-DOPA ethyl ester in an amount which is at least 97%, by weight, of the active ingredient, and L-DOPA in an amount which is less than 1% by weight of such active ingredient is provided by this invention. This invention also provides a process for preparing such a composition. Further, this invention provides a method of treating a patient suffering from Parkinson's disease which comprises administering to a patient a pharmaceutical composition comprising a therapeutically effective amount of L-DOPA ethyl ester and a pharmaceutically acceptable carrier.
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