Syntheses Using Pyridinium Salts

Abstract

Abstract This review discusses syntheses leading to a new type of N‐vinylpyridinium salts, to novel anionocyanines, to aminophenazines and alloxazines, as well as to (aza‐) dehydroquinolizinium, acridizinium, and morphanthridizinium salts. In addition, Mannich reactions and aminoalkylations at active methylene groups of cycloimmonium salts, and their reactions with amines are treated. The possibilities offered by the “Ortoleva‐King” reaction are demonstrated using numerous examples, such as a new route leading to the yohimbine skeleton.