Die Aminoalkylierung von Chinoxalinen und Chinoxalonen 6. Mitteilung über grignard‐reaktionen mit halogenalkylaminen [1]

Publisher Website
Google Scholar
Abstract
Quinoxaline and 2(1H)‐quinoxalones react with organomagnesium salts differently from the corresponding phthalazines and quinazolines. 3‐Dimethylaminopropyl‐magnesiumchloride alkylates quinoxaline easily by addition to the 2 and 3 position forming a tetrahydroquinoxaline 2, which can be dehydrogenated to the corresponding dialkylated quinoxaline 3. The monosubstituted dihydroquinoxaline 5 is obtained only with difficulty. It can equally be dehydrogenated, yielding 6.Quinoxalones react with CH3MgI, C6H5MgBr, (CH3)2N(CH2)3MgCl by addition to the 3,4‐CN bond (not at the CO‐group), yielding 11–13. These dihydroquinoxalones are dehydrogenated to the 3‐substituted 2(1H)‐quinoxalones 14–16. Only 3‐phenyl‐quinoxalone adds a Grignard reagent at the CO group, forming a 2‐substituted 3‐phenylquinoxaline (26). 3‐Methyl‐quinoxalone exhibits an abnormal behaviour: It is deprotonated by the mentioned reagents at the CH3 group, and the 3‐methylenequinoxalone‐anion so formed attacks another molecule of methylquinoxalone, finally yielding 32 and 33.