Synthese von enantiomerenreinen Violaxanthinen und verwandten Verbindungen

Syntheses of Enantiomerically Pure Violaxanthins and Related Compounds The epoxides 16 and ent- 16 , prepared by Sharpless-Katsuki oxidation of 15 in excellent yield and very high enantiomeric purity, were used as synthons for the preparation of (+)-(S)-didehydrovomifoliol (45) , (+)-(6S, 7E, 9E)-abscisic ester 46 , (+)-(6S, 7E, 9Z)-abscsic ester 47 , (?)-(3S, 7E, 9E)-xanthoxin (49) , (?)-(3R, 7E, 9E)-xanthoxin (50) , (3S, 5R, 6S, 3′S,5′R, 6′S, all-E)-violaxanthin (1) (3R, 5R,6S,3′R,5′R,6′S, all-E)-violaxanthin (55) and their (9Z) (see 53 , 57 ), (13Z) (see 54 , 58 ), and (15Z) (see 60 ) isomers. The novel violadione ( 61 ) was prepared from 1 by oxidation with DMSO/Ac₂O. By base treatment, 61 was converted into violadienedione (62) , a potential precursor of carotenoids with phenolic end groups.     

Synthese von Ceramiden und verwandten Verbindungen

Zusammenfassung Im Verlauf der Synthese von N-Myristoyl-3-O-acetyl-dl-sphingosin (9) wurden folgende Verbindungen erstmalig dargestellt: N-Myristoyl-dl-sphingosin (6), 1-O-Trityl-N-myristoyl-dl-sphingosin (7) und 1-O-Trityl-N-myristoyl-3-O-acetyl-dl-sphingosin (8). Weiters wurdendl-threo-1,3-Dihydroxy-2-N-(2-O-acetyl-dl-cerebronyl)-4-cis-octadecen (2) und 2-O-Acetyl-dl-cerebronyl-n-butyl-amid (4) erstmalig sowie N-Lignoceryl-dl-sphingosin (10) auf einem verkürzten Weg synthetisiert. IR-Spektren bestätigten die Konstitution der Verbindungen.

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Synthesis of ceramides and related compounds (sphingolipides, III)

In the course of the synthesis of N-myristoyl-3-O-acetyl-dl-sphingosine (9) the following new compounds have been prepared: N-myristoyl-sphingosine (6), 1-O-trityl-N-myristoyl-dl-sphingosine (7), and 1-O-trityl-N-myristoyl-3-O-acetyl-dl-sphingosine (8).Furthermore,dl-threo-1,3-dihydroxy-2-N-(2-O-acetyl-dl-cerebronyl)-4-cis-octadecene (2) and 2-O-acetyl-dl-cerebronyl-n-butylamide (4) have been synthesized for the first time and N-lignoceryl-dl-sphingosine (10) has been obtained by a simplified procedure. IR spectroscopy was used to ascertain the structures of these compounds.

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Herrn Prof. Dr.J. Schormüller zum 65. Geburtstag gewidmet.     

Eine einfache Synthese von Rosenfuran und verwandten Verbindungen

A Simple Synthesis of Rose Furan and Related Compounds 3-Brom-2-furyllithium was found to be easily accessible by treatment of 3-bromofuran with lithium diisopropylamide. It served as a key compound for the synthesis of furan derivatives, among them the “rose furan”.     

Synthese von ‘D-Isothreonin’ und ‘L-Alloisothreonin’ aus L-Alanin

Synthesis of ‘D -Isothreonine’ and ‘L -Alloisothreonine’ Starting from L -Alanine Starting from L -alanine, ‘D -isothreonine’ ( = (2R, 3S)-3-amino-2-hydroxybutanoic acid) and ‘L -alloisothreonine’ ( = (2S, 3S)-3-amino-2-hydroxybutanoic acid) were synthesized.     

Synthese von ‘Push-Pull’-Diacetylenen

Synthesis of ‘Push-Pull’ Diacetylenes The first synthesis of push-pull diacetylenes of type 1 is described. Reaction of perchlorobutenyne ( 8 ) with two equivalents of dialkylamine, followed by dechlorination using two equivalents of butyllithium gives lithio-dialkylamino-diynes 7 . Final acylation of these intermediates leads to push-pull diacetylenes 1b–1e in good yields. The method allows the introduction of both push and pull substituents in a simple one-pot-procedure. In addition, 1a is prepared by hydroxymethylation of lithio-morpholino-diyne 7c , followed by oxidation with manganese dioxide in acetone.     

Synthese von ‘Push-Pull’-Oligoacetylenen

Synthesis of ‘Push-Pull’-OligoAcetylenes ‘Push-pull’ triacetylenes 11a , b , c , as well as ‘push-pull’ tetraacetylene 13b have been prepared by reaction of the corresponding trichloroene(oligoinyl)amines 9 and 10 with 2 mol-equiv. of BuLi followed by acylation. The sequences (Schemes 3 and 4) are very simple and straightforward, they could in principle be applied to the synthesis of ‘push-pull’ pentaAcetylenes 15 and hexaacetylenes 17 (Scheme 5). Main limitations are the moderate yields as well as the low thermal stability of push-pull oligoacetylenes.     

Synthese von ‘Push-Pull’- Eninen

Synthesis of ‘Push-Pull’ Enynes ‘Push-pull’ enynes 1a–1f are easily available by Pd catalyzed coupling of stannyl-ynamines 15 and silylynamines 16 with β-iodo-enones 8 (Schemes 7 and 8).     

Technische Verfahren zur Synthese von Carotinoiden und verwandten Verbindungen aus 6-Oxo-isophoron. V. Synthese von Astacin

Technical Procedure for the synthesis of Carotenoids and Related Compounds from 6-Oxo-isophorone

1 Teil 4 dieser Reihe: [1].

. V. Synthesis of Astacene Starting from optically inactive astaxanthin intermediates, the highly oxygenated carotenoid astacene was synthesized in seven steps (55% overall yield from 6-oxo-isophorone). Key features of the new approach are base- and acid-catalyzed rearrangements of acetylenic intermediates such as those described in Schemes 2, 7 and 8.     

Zur Bestimmung von Antihistaminen und verwandten Verbindungen

Ohne Zusammenfassung     

Versuche zur Synthese von ‘Push-Pull’-Diacetylenen

Attempted Synthesis of Push-Pull Diacetylenes Two alternative synthesis of push-pull diacetylenes of type 1 (5-amino-2,4-alkadiynals) are investigated. A bromination-dehydrobromination sequence starting with 5-dimethylamino-2,4-pentadienal ( 2 ) as well as the application of the well-known Cadiot-Chodkiewicz coupling reaction give new intermediates 3–5 , and 7 and 8 , respectively, but fail to give the target molecules 1 .     

Synthese und Eigenschaften von 1,1,3,3-Tetrakis(pentafluorphenyl)-cyclo-di(silthian) und verwandten Verbindungen

Summary The synthesis of tetrakis(pentafluorophenyl)-cyclo-di(silthiane) and related compounds by reacting organosubstituted silanes with sulfur or hexamethyldisilthiane is reported The compounds are characterized by analysis, by relative molecular mass, by¹H,¹³C,¹⁹F, and²⁹Si NMR spectroscopy, and by mass and IR spectra, respectively. Two²⁹Si NMR signals of different intensity found for compounds with two different organic substituents on silicon are explained by the existence of diastereomers.

     

Die Ultraviolettabsorption von organischen Peroxyden und verwandten Verbindungen

Zusammenfassung Es wird die Ultraviolettabsorption (in Benzinlösung im Bereich bis ungefähr 2200 ) von Benzoylperoxyd, o- und p-Toluylperoxyd, o-, o- und p-, p-Dichlorbenzoylperoxyd, Cinnamoylperoxyd, Tetralinhydroperoxyd, Benzoesäureanhydrid, o- und p-Toluylsäureanhydrid, Zimtsäureanhydrid gemessen.In dem untersuchten Bereich liefert die –O–O-Gruppe praktisch keinen Beitrag zur Lichtabsorption.Mit 5 Abbildungen.     

Synthese, 13C-NMR-Spektren und räumliche Struktur von ‘Push-Pull’-Diacetylenen

Synthesis, ¹³C-NMR Spectra, and X-Ray Investigation of ‘Push-Pull’ Diacetylenes Phenyl-substituted ‘push-pull’ diacetylenes 1f and 1g have been prepared by acetylation and benzoylation of the appropriate lithiodiynylamines 4 (Scheme 2). ¹³C-NMR spectra of diacetylenes 1a–g (Table 1) are discussed with respect to the expected polarisation of the diacetylene unit by ‘push’ and ‘pull’ substituents. X-Ray investigations of 1c , 1e , and 1f have been performed in view of the planned solid-state polymerisation of ‘push-pull’ diacetylenes. In the crystalline state, diacetylenes 1c and 1f are stacked, however, the stacking parameters do not allow a solid-state polymerisation.     

Synthese von triafulvalen-vorstufen durch ‘carben-dimerisierung’ von 1-halogeno-1-lithiocyclopropanen

Synthesis of Triafulvalene Precursors by ‘Carbene-Dimerization’ of 1-Halogeno-1-lithiocyclopropanes Bi(cyclopropylidenes) 7a , 7c , and 7e are available in a simple one-pot reaction by treating 1,1-dibromocyclo-propanes 5 at ?95° with BuLi and CuCl₂. Attempts towards triafulvalene precursors with good leaving groups are reported. The most promising attempt makes use of 2,2′-bis(phenylthio)-3,3′-bis(trimethylsilyl)-1,1′-bi(cyclopropylidene) (7c) which has been oxidized to give the bis(phenylsulfonyl) derivative 7g. So far, F^?-induced elimination experiments with 7g failed.     

Photo-induzierte Bildung von Peroxiden in Sacchariden und verwandten Verbindungen

Ohne Zusammenfassung