- Syntheses and Cardiovascular Activity of Stereoisomers and Derivatives of Eburnane Alkaloids
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The synthesis of all the possible isomers of the eburnamenine-vincamine type alkaloids 1b, 2a*, 3a and derivatives 4, 8, 9, 10 is described.Structures were determined by 1H- and 13C-NMR spectroscopy including special techniques such as DR, DEPT, DNOE, and 2D-HSC.In contrast to the known cerebrovascular effects of cis-(3S,16S) compounds, trans-(3S,16R) derivatives show a significant peripheral vasodilator effect. Key Word: Eburnanes / Alkaloids / Cardiovascular effects / Indoloquinolizines
- Czibula, Laszlo,Nemes, Andras,Visky, Gyoergy,Farkas, Maria,Szombathelyi, Zsolt,et al.
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p. 221 - 230
(2007/10/02)
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- SYNTHESIS OF STEREOISOMERIC VINCAMINES
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The synthesis of (+/-)-vincamine (I), (+/-)-16-epi-vincamine (XVIII) and (+/-)-16-epi-21-epivincamine (XVII) from 1-ethyl-2,3,4,6,7,12-hexahydroindoloquinolizine (IV) and 2-chloroacrylonitrile is described.It is characterized by a novel method of oxidation of the key intermediates, (+/-)-deoxyvincamine (II) and (+/-)-16-epi-21-epi-deoxyvincamine (XIII) with oxodiperoxymolybdenum (pyridine) (hexamethylphosphoric triamide).The deoxy derivatives II and XIII were prepared by direct or stepwise acid or alkaline hydrolysis od stereoisomeric (+/-)-eburnane-16-carbonitriles IX-XII, obtained by reduction of the primary immonium salt V, and subsequent esterification.In some cases, the hydrolysis is accompanied by epimerization at C(16).
- Koblicova, Zdena,Holubek, Jiri,Trojanek, Jan
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p. 2722 - 2730
(2007/10/02)
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- A NEW APPROACH TO (+/-)-APOVINCAMINE
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A new approach to (+/-)-apovincamine, 2, is reported which bypasses the formation of (+/-)-vincamine, 1, and includes the dehydration of the β-hydroxy ester 7, obtained by regio-controlled alkylation of the stereochemically suitable aldehyde 6 with methyl chloroacetate.Using ethyl chloroacetate, the clinically useful apovincamine analogue, (+/-)-Cavinton, 3, is obtained. (+/-)-Apovincamine is then converted to (+/-)-vincamine, 1, by base-catalyzed oxygenation of the mixture of (+/-)-dihydroapovincamines 8 and 9.
- Danieli, Bruno,Lesma, Giordano,Palmisano, Giovanni
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p. 257 - 268
(2007/10/02)
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- 14-Substituted vincanes
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A compound of the formula (I) STR1 wherein X stands for a hydrogen atom, an optionally substituted aliphatic or aromatic sulfonyloxy group, a thiocyanato group, an azido group or an amino group optionally mono- or disubstituted by aliphatic, cycloaliphatic, aromatic or araliphatic hydrocarbon groups, acyl, alkyloxycarbonyl, cycloalkyloxycarbonyl, aryloxycarbonyl, aralkyloxycarbonyl, aminocarboimido groups or the substituents of the said amino group may form with the nitrogen atom thereof a five-, six- or seven-membered saturated or unsaturated heterocyclic ring optionally containing a further nitrogen, oxygen or sulfur hetero atom, and a quaternary salt or acid addition salt thereof. The compounds are useful in the treatment of arteriosclerosis and high blood pressure.
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