Search results for "Aliphatic compound"
showing 10 items of 53 documents
A novel photochemical 1,4-acyl migration in enol esters. The photolysis of enol acetates of 3-phenylpropiophenones
1987
Abstract Photolysis of the enol acetates 1a,b gives the 1,4-diketones 4a,b by a mechanism involving a primary homolytic carbonyl—oxygen bond cleavage, followed by 1,2-hydrogen shift and in cage recombination.
Carbohydrates as chiral templates: Diastereoselective Ugi synthesis of (S)-amino acids using O-acylated D-arabinopyranosylamine as the auxiliary
1989
Abstract Enantiomerically pure (S)-amino acids are synthesized via a highly diastereoselective Ugi reaction using 2,3,4-tri-O-pivaloyl-α-D-arabinopyranosylamine as the chiral template.
Unexpected formation of chroman-4-ones during the synthesis of 4-hydroxymethyl-2H-chromenes from 4-aryloxybut-2-yn-1-ols
1986
Abstract The unexpected formation of chroman-4-ones by refluxing 4-aryloxybut-2-yn-1-ols in diethylaniline has been studied, 4-hydroxymethyl-2H-chromene and chroman-4-carboxaldehyde derivatives being established as intennediates.
Mass spectra of halogenated esters 6—Methyl esters of some trihalogenated propanoic and butanoic acids
1984
The mass spectral fragmentation of trihalogenated methyl esters, formed in the reactions of monochlorinated methyl propenoates and 2-butenoates with Cl2, BrCl and Br2, have been investigated. In most cases α-cleavage gives the base peak, [COOCH3]+, the peaks originating from the subsequent losses of one or two halogen atoms also being abundant. The primary loss of a halogen atom is more prominent in the C4 derivatives, Br˙ and Cl˙ being preferentially lost from the 2- and 3-positions, respectively. The McLafferty rearrangement yields in one case the base peak; the 2-halo compounds could in general be distinguished by that fragmentation. Typical for all 2-bromo-substituted methyl butanoates …
Modified photobehavior of carboxylic acid derivatives induced by protonation
1987
Abstract A series of carboxylic acid derivatives 1–6 containing a second interacting function have been converted into the corresponding O -protonated species or acylium ions upon treatment with 96% sulfuric acid or oleum, respectively, at room temperature. The resulting stable cations have been spectroscopically characterized and submitted to irradiation. Cis-trans photoisomerization was observed in the ionic speciesderived from trans -crotonic, fumaric and maleic acids, and maleic anhydride. By contrast protonated crotonolactone 5a+ was found to be photostable. Finally, protonated α-bromobutyrolactone 6a+ was clean and efficiently dehydrohalogenated to 5a+ upon irradiation. Since the norm…
Telechele des methylpropens durch kationische polymerisation
1986
Amorcage par des hydrocarbures aromatiques et aliphatiques contenant des groupes terminaux chlorure d'isopropyle, associes a du trichlorure de bore. Mecanisme. Recyclage du coamorceur et du solvant
H2-Antihistaminika, 33. Mitt. Synthese und H2-antagonistische Aktivität heteroaromatischer (Thio)Carboxamide und Triazol(thi)on-Derivate des Piperidi…
1987
Die Zyklisierung der (Thio)Semicarbazide la, b mit N-Cyan-diphenylimidocarbonat, N-Cyan-dimethyldithioimidocarbonat, Aminocrotonsaurenitril und Acetessigester gibt die heteroaromatischen (Thio)Carboxamide 5a, b und 7–9. Beim Einwirken von NaOH auf die (Thio)Biharnstoffe 12 und 13 sowie die (Oxa)Thiadiazoldiamine 19 und 20 werden die Triazol(thi)one 15 und 17 erhalten. Am Vorhof des Meerschweinchens zeigen 5a, 7 und 8 eine mit Cimetidin vergleichbare Histamin-H2-antagonistische Wirkung. H2-Antihistaminics, XXXIII: Synthesis and H2-Antagonistic Activity of Heteroaromatic (Thio)Carboxamides and Triazole(thi)one-Derivatives of Piperidinomethylphenoxypropylamine The (thio)semicarbazides la, b ar…
WEITERE SELEKTIVITÄTSSTUDIEN AM BEISPIEL EINES ARYLSULFONYLACETYLENS
1984
Abstract With 1-(phenylsulfonyl)propyne-(1) 1 as a model compound, we have investigated the competition reactions with RSH, RNH2 and ROH (R=n-Bu). With RSH and RNH2, the cis-trans-isomeric olefins 2 to 5 are formed. ROH does not react under these conditions. The compounds 6 and 7 are obtained only with ROH as the alcoholate. The reactivity of 1 with nucleophiles is increased in comparison to phenylvinyl sulfone; the selectivity of 1 is, however, decreased. The difference in reactivity of 1 and phenylvinyl sulfone corresponds to ca. 10:1. Mit 1-(Phenylsulfonyl)-propin-(1) 1 als Modellverbindung haben wir die konkurrierenden Umsetzungen mit RSH, RNH2 und ROH (R=n-Bu) studiert. Mit RSH und RNH…
H2-Antihistaminika, 32. Mitt. Synthese und H2-antagonistische Wirkung von N-[3-(3-Piperidino-methyl-phenoxy)propyl]-1.3.4-oxadiazol-2-aminen
1986
Es wird uber die Synthese und H2-antagonistische Wirksamkeit von N-[3-(3-Piperidinomethyl-phenoxy)-propyl]-1.3.4-oxadiazol-2-amin und dessen 5-substituierte Derivate berichtet. H2-Antihistaminics, XXXII: Synthesis and H2-Antagonistic Activity of N-[3-(3-(Piperidinomethyl)phenoxy)propyl]- 1.3.4-oxadiazol-2-amines The synthesis and H2-antagonistic activity of N-[3-(3-(piperidinomethyl)phenoxy)propyl]-l.3.4-oxadiazol-2-amine and its 5-substituted derivatives are reported.
Polycondensed nitrogen heterocycles. Part 22. Pyrrolo[3,4-d]-1,2,3-triazines: A new ring system as potential antineoplastic agent
1989
Diazotization of the 3-aminopyrrole-4-carboxamides 6a,b under different conditions directly led to the new ring system pyrrolo[3,4-d]-1,2,3-triazine in excellent yields through an intramolecular coupling reaction. In all the cases it was impossible to isolate the intermediate 3-diazopyrroles.