Abstract Aryl β-chlorovinyl ketones react with the methyl group of 2, 6-di-tert-butyl-4- methylpyrylium perchlorate in the presence of pyridine to yield doubly vinylogous 4H- pyrones 3. Only one configuration and conformation from the eight possible structures appears to be present according to IR, UV-VIS, and NMR data. The mass spectral fragmentation is discussed. Protonation of 3 converts these products into pyrylium salts ...
