Synthese von N-Methyl- und N,N-Dimethylmerucathin sowie von N-Methyl- und N,N-Dimethylpseudomerucathin aus L-Alanin

Synthesis of N-Methyl- and N,N-Dimethylmerucathine and of N-Methyl- and N,N--Dimethylpseudomerucathine Starting from L -Alanine Starting form L -alanine, N-methylmerucathine (= (3R,4S)-4-(methylamino)1-phenyl-1-penten-3-ol; (3R,4S,)- 6 ), N,N-dimethylmerucathine (= (3R,4S)-4-(dimethylamino)-1-phenyl-1-penten-3-ol; (3R,4S)- 9 ), N-methylpseudomerucathine (= (3S,4S)-4-(methylamino)-1-phenyl-1-penten-3-01; (3S,4S)-6), and N,N-dimethylpseudomerucathine (= (3S,4S)-4-(dimethylamino)-1-phenyl-1-penten-3-ol; (3S,4S)- 9 ) were synthesized. The four compounds were analyzed by HPLC and compared with a natural khat extract.     

Synthese von enantiomerenreinen ‘Grasshopper’-Ketonen und verwandten Verbindungen

Synthesis of Optically Pure Grasshopper Ketone and of Its Diastereoisomers and Related Compounds Starting from our previously described synthon 1 , the synthesis of four enantiomerically pure grasshopper ketons (diastereoisomeric 4-(2′,4′-dihydroxy-2′,6′,6′-trimethylcyclohexylidene)but-3-en-2-ons) and of their oxo derivatives was performed. Spectral and chiroptical data are presented.     

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).     

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, 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.     

Synthese von Indolen und Isochinolonen aus Phenylmalonylheterocyclen

A new synthesis of the indole system has been achieved by chclodehydrogenation of amino phenylmalonate heterocycles. Thus, the 4-amino coumarins1 a,b or the 4-amino-2-quinolones1 c–g are converted to the indoles2 with palladium on charcoal in boiling diphenyl ether. The reaction of the aminocompounds1 with diphenyl carbonate yields the fused polycyclic isoquinolones4.

     

Synthese von Polythioamiden aus Dithioamid und Diamin

Ohne Zusammenfassung     

Synthese und Charakterisierung von Copolymeren aus Azo-Initiatoren und Styrol

Ohne Zusammenfassung     

Synthese von derivaten der cinchona-alkaloide—XXXII Synthese von dihydrocorynanthean und 3-epidihydrocorynanthean aus cinchonin

Starting from cinchonine, 3-epidihydrocorynantheane was synthesized through 2′-oxohexahydrocinchonine. Quinine was transformed into 10-methoxydihydrocorynantheane by the same reaction steps. In both cases, it was found that Oppenauer oxidation of the secondary hydroxyl group at quinine-numbering C-9 was accompanied with no configurational change at the neighboring C-atom, which originated from C-8 in quinuclidine moiety. 3-Epidihydrocorynantheane was converted to dihydrocorynantheane by oxidation with mercuric acetate and then sodium borohydride reduction.