The Synthesis of New Pyrylium and Pyridinium Salts

The synthesis, properties, and applications of symmetrical and unsymmetrical pyrylium and pyridinium salts is investigated. Our group has found particular interest in chiral pyrylium salts due to the fact that they are almost unknown in the literature. We have applied the reaction of acyl chlorides with tert-butanol to the preparation of new pyrylium tetrafluoroborate salts. Some of these pyrylium salt derivatives form diastereomers when prepared. Moreover, they are favorable to study epimerization at the alpha centers. The ease of epimerization at pyrylium chiral centers has not been studied previously. We also applied the reaction of acyl chlorides with dypnone to form asymmetrical pyrylium salts. Our group has also found interest in positively charged pyridinium salts, which provide a route for the possible improvement on the bioavailability of hydrophobic compounds and also an interesting interaction with different substrates. We optimized reaction conditions for reacting substituted pyrylium salts with primary amines to obtain pyridinium salts. Future work will be directed towards obtaining pyridinium salts from primary amines with known biological activity. The objective of this study is to synthesize new pyrylium and pyridinium salts