Ya. Ibrahim et Ah. Moustafa, Interesting synthetic approaches towards [1]benzopyrano[4,3-b]quinolines via intramolecular reaction of nitrilium salts, J CHEM R-S, (4), 1999, pp. 254-255
The o-allyloxybenzanilides Za,b,d and o-propargyloxybenzanilides 3a-f are p
repared and converted to the corresponding dihydro[1] benzopyrano [4,3-b] q
uinolinium hexachloroantimonate 6a and [1] benzopyrano[4,3-b] quinolines 9a
-e, 10 upon treatment with PCl5 followed by SbCl5.