Synthesis and reactivity of 1,2,4-triazolo[1,5-c]quinazolines

The preparation of 1,2,4-triazolo[1,5-c]quinazolines 4a-d , 5 , 8a-d by cyclocondensation of 1a-c with carboxylic acids and carboxylic anhydrides, respectively, is described. By different pathways, the 5-thioxo-5,6-dihydro-1,2,4-triazolo[1,5-c]quinazolines 4a-d react with hydrazine hydrate or amines with the formation of 5-substituted 1,2,4-triazolo[1,5-c]quinazolines 9 and 10a-d . Cyclocondensation of 9 with carboxylic acids, carboxylic anhydrides, and nitrous acid, respectively, leads to the new anellated heterocycles bis-1,2,4-triazolo[4,3-a:1,5-c]quinazoline 13 and tetrazolo [1,5-a]-1,2,4-triazolo[1,5-c]quinazoline ( 14 ).     

Enhanced structure determination of beta-pyrrole and N-substituted porphyrins by desorption chemical ionization mass spectrometry.

The extensive macrocycle—but minimal substituent—fragmentation occurring in the chemical ionization mass spectra of porphyrins when ammonia, rather than hydrogen, is the reagent gas leads to more detailed structure determinations.     

Eine Methode zur Identifizierung und Unterscheidung von n-Propyl- und Isopropylhalogenid mit Hilfe von Triphenylphosphin

Ohne Zusammenfassung     

Eisen(III)

Ohne Zusammenfassung     

Ninhydrin

Ohne Zusammenfassung