1112291-05-0Relevant articles and documents
Efficient and versatile synthesis of 2,3-Dialkylimidazo[4,5-b]quinolin-9- ols by microwave-assisted one-pot Beckmann rearrangement
Hwang, Bo Hyun,Choi, Eun Bok,Lee, Hyeon Kyu,Yang, Hee Cheol,Chung, Bong Young,Pak, Chwang Siek
experimental part, p. 3569 - 3578 (2009/07/04)
A direct microwave-assisted one-pot Beckmann rearrangement of 3-acyl-2-(alkylamino)quinolin-4-(1H)-ones in ethanol-pyridine (2:1) provides 2,3-dialkylimidazo[4,5-b]quinolin-9-ols as major products along with 2-alkyl-N-alkyloxazolo[4,5-c]quinolin-4-amines and 3-alkyl-N-alkylisooxazolo[4, 5-c]quinolin-4-amines as minor products. Reactions of 3-acylquinoIin-4-(1H)- ones containing secondary amine substituent at C-2 give 2-alkyloxazolo[5,4-b] quinolin-9-ols as major products via elimination of the secondary amine group. A mechanism proposed for the formation of Beckmann rearrangement products involves initial generation of a nitrilium ion intermediate, which is trapped either by the adjacent nitrogen of the γ-amino group to form imidazoquinolinols or by the oxygen of γ-hydroxy group of the tautomeric form of the ketoxime to form oxazoloquinolinamines. Georg Thieme Verlag Stuttgart · New York.