A novel photoinduced ring opening and isomerization of adamantane-2-spiro isoxazolines using Mo(CO)6

The Mo(CO)₆-mediated photoinduced ring-opening reactions of adamantane isoxazolines involve novel rearrangement that provide enaminoketones as major products and β-hydroxy ketones as minor ones; in contrast, only β-hydroxy ketones and α,β-unsaturated ketones were obtained under thermal condition.     

The steric structure of multiflorine methylation products

Summary Multiflorine (1) — a minor lupine alkaloid — treated by methyl lithium or methyl magnesium iodide affords 4S-4-hydroxy-4-methyl-2,3-didehydrosparteine (2) and 2S-2-methyl-4-oxosparteine (3), respectively, as the dominating products. Their steric structure, determined by¹H and¹³C NMR techniques, points to stereospecific preferences of these reactions. The observed nucleophilic 1,2- and 1,4-additions indicate that regiospecificity of the action of MeLi or MeMgI on multiflorine is different from that of the so far known similar alkylation of other enamino ketones.

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Die räumliche Struktur von Methylierungsprodukten des Multiflorins

Zusammenfassung Multiflorin (1), ein Lupin-Nebenalkaloid, ergibt bei Umsetzung mit Methyllithium oder Methylmagnesiumiodid 4S-4-Hydroxy-4-methyl-2,3-didehydrospartein (2) und 2S-2-Methyl-4-oxospartein (3) als Hauptprodukte. Ihre NMR-spektroskopisch (¹H und¹³C) aufgeklärte räumliche Struktur weist auf eine Stereoselektivität der erwähnten Reaktionen hin. Die beobachteten nucleophilen 1,2- und 1,4-Additionen zeigen, daß sich die Regiospezifität der Einwirkung von MeLi oder MeMgl auf Multiflorin von jener bis jetzt bekannter Alkylierungen von Enaminoketonen unterscheidet.

     

β-Bromodifluoromethyl β-enaminoketones: versatile synthetic intermediates for synthesis of CF2-containing compounds

A series of N-aryl β-bromodifluoromethyl β-enaminoketones were regioselectively synthesized in good yield by the reaction of N-aryl bromodifluoroacetimidoyl chlorides with methyl ketones. β-Bromodifluoromethyl β-enaminoketones smoothly cyclized to give a novel class of cyclic (2,2-difluoro-5-phenyl-furan-3-ylidene)-aryl-amines under basic condition. An intramolecular halophilic substitution mechanism was proposed.     

Synthesis of substituted 1-trifluoromethyl and 1-perfluoroalkyl-3-(arylamino)prop-2-en-1-one: advances in the mechanism of Combes 2-trifluoromethyl and 2-perfluoroalkyl quinolines synthesis

We report a new synthesis and our study of the mechanism of formation of substituted 1-trifluoromethyl and 1-perfluoroalkyl-3-(phenylamino)prop-2-en-1-one starting from 3-(R-phenoxy)-3-perfluoroalkyl-prop-2-enals and arylamines. Reactivity study of the intermediates confirmed that 3-perfluoroalkyl-N,N′-diphenyl-1,5-diazapentadienes are the synthetic intermediates of the synthesis of 2-perfluoroalkylquinolines. The mechanism of the reaction of 1-trifluoromethyl and 1-perfluoroalkyl-3-(phenylamino)prop-2-en-1-one with POCl₃ was studied. To our knowledge this is the first detection and isolation of N,N′-diaryldiazapentadiene derivatives as intermediates in the Combes F-alkyl substituted quinoline synthesis starting from enaminoketones. Finally, we succeeded isolating and identifying unsymmetrically substituted 2-perfluorolakyldiazapentadiene.     

Cathodic synthesis of 2-amino-2-propene-1-ones electrolytical studies on vinylazides,VII

The cathodic preparation of enamino ketones from enazidoketones has been generalised to include heteroaromatic and aliphatic derivatives. Mechanistically the role of different sites of protonation, either on N¹ of the N₃-group or on carbonyl depending on electrolysis potential and acid strength, apparent by product distribution, is clarified. Aldehydic groups are preferentially reduced compared to the vinylazide part. Purely aliphatic azidoketones yield conjugated dienes under reductive acetylation, which might be useful for cycloaddition reactions.Die kathodische Synthese von Enaminoketonen aus ungesättigten Azidoketonen wurde auf heteroaromatisch substituierte und auf rein aliphatische Derivate übertragen. Zum Reduktionsmechanismus wurde der Einfluß verschiedener Stellen der Protonierung (am N¹ der N₃-Gruppe bzw. an der Carbonylgruppe), abhängig von Potential und Säurestärke, untersucht. Aldehydische Gruppen als weitere funktionelle Gruppen im Enazid werden leichter als die Vinylazide reduziert. Die rein aliphatischen Enazidoketone ergeben bei reduktiver Acylierung konjugierte Diene.

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Elektrolytische Untersuchungen an Vinylaziden, 7. Mitt.: Kathodische Synthese von 2-Amino-2-propen-1-onen

     

1-Bromo-2-trifluoroacetylcyclobutenes as novel building blocks for the construction of trifluoromethyl substituted heterocycles. Part 3: Synthesis of trifluoromethylsubstituted pyridines, condensed with cyclobutene moieties

This paper describes a general synthetic approach to 3-cyano-4-trifluoromethylpyridines fused with cyclobutene rings with variable spiro conjunctions. The reaction of various 1-bromo-2-trifluoroacetylcyclobutenes with ammonia results in the substitution of bromine with an NH₂ group leading to corresponding enaminoketones in high yields, which, in turn, form the target pyridines by treatment with diethyl ethoxymethylencyanophosphonate in the presence of sodium hydride.