InCl3-driven regioselective synthesis of functionalized/annulated quinolines: scope and limitations.
The efficient, regioselective synthesis of functionalized/annulated quinolines was achieved by the coupling of 2-aminoaryl ketones with alkynes/active methylenes/α-oxoketene dithioacetals promoted by InCl(3)  in refluxing acetonitrile as well as under solvent-free conditions in excellent yields. This transformation presumably proceeded through the hydroamination-hydroarylation of alkynes, and the Friedländer annulation of active methylene compounds and α-oxoketene dithioacetals with 2-aminoarylketones. In addition, simple reductive and oxidative cyclization of 2-nitrobenzaldehyde and 2-aminobenzylalcohol, respectively, afforded substituted quinolines. Systematic optimization of the reaction parameters allowed us to identify two-component coupling (2CC) conditions that were tolerant of a wide range of functional groups, thereby providing densely functionalized/annulated quinolines. This approach tolerates the synthesis of various bioactive quinoline frameworks from the same 2-aminoarylketones under mild conditions, thus making this strategy highly useful in diversity-oriented synthesis (DOS). The scope and limitations of the alkyne-, activated methylene-, and α-oxoketene dithioacetal components on the reaction were also investigated.
Department of Chemistry, Faculty of Science, Banaras Hindu University, Varanasi-221005, India.
Tanmoy
T
Chanda
Rajiv Kumar
RK
Verma
Maya Shankar
MS
Singh
D000480:Alkynes / Q000737:chemistry; D003500:Cyclization; D007204:Indium / Q000737:chemistry*; D007659:Ketones / Q000737:chemistry; D008968:Molecular Conformation; D011804:Quinolines / Q000138:chemical synthesis / Q000737:chemistry*; D013237:Stereoisomerism
D000480:Alkynes; D007659:Ketones; D011804:Quinolines; D007204:Indium; C020758:indium trichloride