Synthesis of pyrylium salts and pyridine bases by the bisacylation of cyclic tertiary alcohols

The catalytic acylation of 1-methyl- and 1-ethylcyclopentan-1-ols, 1-methyl- and 1-ethylcyclohexan-1-ols, 1-methylcycloheptan-1-ol, and 1-methyl- and 1-ethyl-1-tetralols with carboxylic acid anhydrides in the presence of 70% HClO₄ has been studied. A method for the synthesis of substituted 3,4-cycloalkeno-3,4-dihydro(3,42, 1)naphthopyrylium salts and the corresponding pyridine bases has been developed.