The reaction of methyl 3-(arylamino)acrylates with hydrogen iodide
gave 1,2-dihydroquinoline-3-carboxylic acid derivatives at room
temperature. This reaction proceeds efficiently in alcoholic solvent;
bulky tert-butyl alcohol is the best
solvent to give the 1,2-dihydroquinoline derivatives. It is particularly
interesting that hydrogen iodide is the most efficient acid to achieve
this reaction in tert-butyl alcohol.
Various substituents at the phenyl ring are applicable. Compounds
bearing meta-substituted phenyl ring
with electron-donating group led to the corresponding 1,2-dihydroquinoline
derivatives in good yields.
cyclization - hydrogen iodide - heterocycles - solvent effects - substituent effects