N-Acetyl- and N-formyl-ortho-alkenyl(cycloalkenyl)anilines were synthesized. Their reaction with P2O5 or PCl5 afforded quinolines. By reaction of the ortho-alkenyl(cycloalkenyl)anilines with 1-methylimino- or 1-phenylimino-1-chloroethanes amidines were obtained that were cyclized in the polyphosphoric acid. The reaction with the polyphosphoric acid of amidines prepared from alkenylanilines and 1-methylimino-1-chloroethane gave rise to 3-methyl-3,4-dihydroquinazolines; on replacing in the substrate methylimine group for phenylimine one the yield of quinazoline decreased.
N-Acetyl-6-(cyclopent-1-enyl)-2-methylaniline underwent intramolecular cyclization in the presence of HCl in CH2Cl2 at 20 degrees C to form 2,8-dimethylspiro[cyclopentane-1,4'-4'H- 3,1-benzooxazine] in quantitative yield.