text: The Kröhnke pyridine synthesis provides a fairly general method for generating substituted pyridines using pyridine itself as a reagent which does not become incorporated into the final product. The reaction of pyridine with bromomethyl ketones gives the related pyridinium salt, wherein the methylene group is highly acidic. This species undergoes a Michael-like addition to α,β-unsaturated carbonyls in the presence of ammonium acetate to undergo ring closure and formation of the targeted substituted pyridine as well as pyridinium bromide.
  The Ciamician–Dennstedt rearrangement entails the ring-expansion of pyrrole with dichlorocarbene to 3-chloropyridine.
  In the Gattermann–Skita synthesis, a malonate ester salt reacts with dichloromethylamine.
  Other methods include the Boger pyridine synthesis and Diels–Alder reaction of an alkene and an oxazole.