Editing Pyridine (section)

===Other methods===
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 addition|Michael-like addition]] to [[Α,β-Unsaturated carbonyl compound|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.<ref>{{cite journal|first=Fritz |last=Kroehnke |title=The Specific Synthesis of Pyridines and Oligopyridines |journal=Synthesis |date=1976 |volume=1976 |issue=1 |pages=1–24 |doi=10.1055/s-1976-23941|s2cid=95238046 }}.</ref>
[[File:Kroehnke Pyridine Figure 1.png|class=skin-invert-image|600px|Figure 1|center]]
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The Ciamician–Dennstedt rearrangement<ref>{{Cite journal |last1=Ciamician |first1=G. L. |last2=Dennstedt |first2=M. |date=1881 |title=Ueber die Einwirkung des Chloroforms auf die Kaliumverbindung Pyrrols |url=https://onlinelibrary.wiley.com/doi/10.1002/cber.188101401240 |journal=Berichte der Deutschen Chemischen Gesellschaft |language=en |volume=14 |issue=1 |pages=1153–1163 |doi=10.1002/cber.188101401240 |issn=0365-9496}}</ref> entails the ring-expansion of [[pyrrole]] with [[dichlorocarbene]] to [[3-Chloropyridine|3-chloropyridine]].<ref>{{cite journal|doi=10.1021/ja01541a070|last1=Skell |first1=P. S. |last2=Sandler |first2=R. S. |journal= Journal of the American Chemical Society |volume=80|pages= 2024 |year=1958|issue=8|title=Reactions of 1,1-Dihalocyclopropanes with Electrophilic Reagents. Synthetic Route for Inserting a Carbon Atom Between the Atoms of a Double Bond}}</ref><ref>{{cite journal|doi=10.1039/J39690002249|title=Mechanism of heterocyclic ring expansions. Part III. Reaction of pyrroles with dichlorocarbene|year=1969|last1=Jones|first1=R. L.|last2=Rees|first2=C. W.|journal=Journal of the Chemical Society C: Organic|issue=18|pages=2249}}</ref><ref>{{cite journal|last1=Gambacorta |first1=A. |last2=Nicoletti |first2=R. |last3=Cerrini |first3=S. |last4=Fedeli |first4=W. |last5=Gavuzzo |first5=E. |doi=10.1016/S0040-4039(01)94795-1|title=Trapping and structure determination of an intermediate in the reaction between 2-methyl-5-''t''-butylpyrrole and dichlorocarbene|year=1978|journal=Tetrahedron Letters|volume=19|issue=27|pages=2439}}</ref>
[[File:Ciamician-Dennstedt Rearrangement.png|class=skin-invert-image|500px|center|Ciamician–Dennstedt Rearrangement]]
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In the Gattermann–Skita synthesis,<ref>{{cite journal|title = Eine Synthese von Pyridin-Derivaten|trans-title = A synthesis of pyridine derivatives|journal = Chemische Berichte|volume = 49|issue = 1|year = 1916|pages = 494–501|last1 = Gattermann|first1 = L.|last2 = Skita|first2 = A.|doi = 10.1002/cber.19160490155|url = https://zenodo.org/record/1426601|access-date = 29 June 2019|archive-date = 25 September 2020|archive-url = https://web.archive.org/web/20200925145302/https://zenodo.org/record/1426601|url-status = live}}</ref> a [[Malonic ester synthesis|malonate ester]] salt reacts with dichloro[[methylamine]].<ref>{{cite web|archive-url=https://web.archive.org/web/20060616020955/http://www.pmf.ukim.edu.mk/PMF/Chemistry/reactions/gattermann-skita.htm |url=http://www.pmf.ukim.edu.mk/PMF/Chemistry/reactions/gattermann-skita.htm |title=Gattermann–Skita |publisher=Institute of Chemistry, Skopje |archive-date=2006-06-16}}</ref>
[[File:Gattermann-Skita Syntesis.png|class=skin-invert-image|500px|center|Gattermann–Skita synthesis]]
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Other methods include the [[Boger pyridine synthesis]] and [[Diels–Alder reaction]] of an [[alkene]] and an [[oxazole]].<ref>{{Cite journal |author1=Karpeiskii, Y.|author2=Florent'ev V. L. |date=1969 |title=Condensation of Oxazoles with Dienophiles — a New Method for the Synthesis of Pyridine Bases |journal=Russian Chemical Reviews |volume=38 |issue=7 |pages=540–546 |doi=10.1070/RC1969v038n07ABEH001760 |bibcode=1969RuCRv..38..540K |s2cid=250852496 }}</ref>