Photoreaktionen kleiner organischer Moleküle. 4. Mitt. Absorptions-spektren,Photoionen- und Resonanzphotoelektronenspektren von Vinylbromid.

Ohne Zusammenfassung     

Amino substituted 1-oxa-3-azabutatrienium salts: preparation, structure and reaction with carbonyl compounds

N,N-Dimethylformamide ($\text{4a}$) and N,N-dimethylpivalamide ($\text{4b}$) react with carbonyl chloride isocyanate ($\text{5}$) in the presence of antimony pentachloride to afford the amino substituted 1-oxa-3-azabutatrienium hexachloroantimonates $\text{6a}$,$\text{b}$. An X-ray diffraction analysis of $\text{6a}$ confirms the proposed structure. The heterocumulenes $\text{6a}$,$\text{b}$ react with aldehydes, ketones and tertiary carboxamides to give the amino substituted 2-azaallenium salts $\text{13a}$-$\text{O}$ in high yields.     

The reaction of 2,4,6-tris(trimethylsiloxy)-1,3,5-triazine with chlorocarbenium ions: a new access to 1-oxa-3-azabutatrienium and 2-azaallenium salts

Chlorocarbenium salts - of the Vilsmeier-Arnold type react with the silylated isocyanuric acid to give 1-oxa-3-azabutatrienium salts under mild conditions. From reactions of diarylchloromethenium salts - with and ketones or tertiary carboxamides high yields of 2-azaallenium salts were obtained. A few chloro substituted 2-azaallenium salts were prepared from and carbonyl compounds. The mechanisms of the new reactions are discussed.     

Nitrosation of sugar oximes: preparation of 2-glycosyl-1-hydroxydiazene-2-oxides

Oximes of glucose, xylose, lactose, fructose, and mannose have been prepared. Nitrosation of the oximes of glucose, xylose, and lactose with NaNO2/HCl afforded 2-(beta-glycopyranosyl)-1-hydroxydiazene-2-oxides, which were isolated as salts 13, 22, and 28. Nitrosation of fructose oxime 29 furnished fructose, whereas nitrosation of mannose oxime 30 with NaNO2/HCl afforded the 1-hydroxy-2-(beta-D-mannopyranosyl)diazene-2-oxide 32, from which the p-anisidinium salt 31 and the sodium salt 33 were prepared. However, nitrosation of 30 with isopentyl nitrite in aqueous solutions of CsOH or KOH resulted in the formation of the 2-(alpha-D-mannofuranosyl)-1-hydroxydiazene-2-oxide salts 34 and 35, respectively. Methylation of the ammonium 2-(beta-D-glucopyranosyl)-1-hydroxydiazene-2-oxide 13 yielded the 1-methoxy compound, which was benzoylated to afford the tetra-O-benzoate 14a, the structure of which was confirmed by X-ray diffraction analysis. From the glucose O-methyloximes 15 and 16 the N-methoxy-N-nitroso-2,3,4,6-tetra-O-acetyl-beta-D-glucopyranosylamine 18 was prepared. The structure of this compound was confirmed by X-ray diffraction analysis. Treatment of acetobromoglucose with cupferron furnished the 1-(2,3,4,6-tetra-O-acetyl-beta-D-glucopyranosyloxy)-2-phenyldiazene-2-oxide 20.