Chlorinated pentadienals and pentadienones (I) gave complex pyrylium salts (II) when warmed with Lewis acids 10-15 hrs. at 40-50 Deg. The compds. thus prepared are given in the table. Decompn; R, R', Anion, point, %Yield; Cl, H, SnCl6-, 1701-1.5 Deg, 87; 2 ...
1966