Chloracylierung und Bromacylierung von Carbonylverbindungen: Eine in Vergessenheit geratene Carbonylreaktion. I. Präparative Anwendungsbreite

Chloroacylation and bromoacylation of carbonyl compounds: A forgotten carbonyl reaction. I. Scope of the reaction Aliphatic, α,β-unsaturated and aromatic aldehydes as well as aliphatic ketones react with acyl halides to (α-haloalkyl)esters. These bifunctional derivates contain two leaving groups of different reactivity. The scope of this scarcely of this scarcely known carbonyl reaction is discussed.     

Synthesis of amino sugars via isoxazolines DL- and D-lividosamine (2-amino-2,3-dideoxy-ribo-hexose) derivatives from 4-vinyl-1,3-dioxolanes and nitroacetaldehyde acetals

1,3-Dipolar cycloaddition of nitrile oxides, generated from nitroethanol and nitroacetaldehyde derivatives 3, 21 and 22, respectively, and of benzonitrile oxide to 4-vinyldioxolanes 1, 2 gave ca 4:1 erythro/threo mixtures of corresponding isoxazolines. LAH reduction of erytho isoxazolines proceeded with similar (ca 4:1) selectivity to furnish protected ribo-amino-polyols 11, 15,19, DL- and D-lividosamines 31 and 33, respectively, as main products. The DL-lividosamine derivative 33 was obtained pure by crystallization. In the D-series, the corresponding ribo/arabino mixture D-31/D-32 was transformed to the known α-methyl D-lividosaminide D-37.     

Direkte elektrometrische Bestimmung des Fluorid-Ions

Zusammenfassung Die Arbeitsweise einer Fluoridionen-empfindlichen Elektrode wurde geprüft und der Einfluß von Fremdsubstanzen auf die Potentiale untersucht. Die Störungen können durch Maskierung, Pufferung oder durch eine Auswertmethode vermindert werden.

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Summary The working characteristics of a fluoride-sensitive electrode and the influence of foreign substances on the fluoride potentials were tested. Changes in potential can be diminished by masking or buffering. Furthermore, a special addition technique can be applied.

     

Are any non-stereospecific 1,3-dipolar cycloadditions known? A revision

The cycloaddition of 1-benzylidenepyrazolid-3-one betaine to (E)-β-nitrostyrene, which has been claimed to furnish 15–30% non-stereospecific product, revealed stereospecificity up to 99.92% in a renewed study; (Z)-β-nitrostyrene stereoisomerizes under the influence of the 1,3-dipole.     

Synthese von 15-Hydroxy[9]metacyclophan

Synthesis of 15-Hydroxy[9]metacyclophane 3-(1-Nitro-2-oxocyclododecyl)propanal ( 1 ) was converted to 15-hydroxy[9]metacyclophane ( 3 ) on two different routes. In the first case the internal aldol reaction product of 1 was treated with K₂CO₃/THF to give 3 in 29 % yield with regard to cyclododecanone. Alternatively, the aldehyde 1 reacted with a primary amine to form e.g. 4 which gave 3 in the presence of CH₃I/K₂CO₃ in 48 % yield.     

Structure and Stereochemistry of New Sesquiterpene Esters from Echinacea purpurea (L.) MOENCH. (Preliminary communication)

The structure elucidation of four new constituents from the roots of Echinacea purpurea is described. They are shown to be cinnamoyl esters of sesquiterpene alcohols with a germacrane or a guaiane skeleton. First pharmacological results indicate immunological activities.     

Die Bildung von CoAl3Cl11 bei größeren Al2Cl6-Drücken

Formation of CoAl₃Cl₁₁ at higher Al₂Cl₆ Pressures The reaction of CoCl_2,f with Al₂Cl_6,g (≈ 3 atm) is investigated considering every component of the gas phase (Al₂Cl₆, AlCl₃, Al₃Cl₉, CoAlCl₅, CoAl₂Cl₈, CoAl₃Cl₁₁) and the deviation from the ideal behaviour. The conclusion is derived that at 600 K from CoCl_2,s and larger pressures of Al₂Cl₆ besides CoAl₂Cl₈ a small amount of CoAl₃Cl₁₁ is formed.