- Hantzsch pyridine synthesis
The Hantzsch pyridine synthesis or Hantzsch dihydropyridine synthesis is a multi-component
organic reaction between analdehyde such asformaldehyde , 2 equivalents of a β-keto ester such asethyl acetoacetate and a nitrogen donor such asammonium acetate orammonia . [cite journal
title = Condensationprodukte aus Aldehydammoniak und Ketoniartigen Verbindungen
author = Hantzsch, A.
journal =Chemische Berichte
volume = 14
issue =
pages = 1637–1638
year = 1881
doi = 10.1002/cber.18810140214] The initial reaction product is a dihydropyridine which can be oxidized in a subsequent step to apyridine . The driving force for this second reaction step isaromatization .A 1,4-dihydropyridine di
carboxylate is also called a 1,4-DHP compound or a Hantzsch compound. These compounds are an important class ofcalcium channel blocker s and as such commercialized in for instancenifedipine ,amlodipine ornimodipine .The reaction has been demonstrated to proceed in
water as reaction solvent and with direct aromatization byferric chloride orpotassium permanganate in aone-pot synthesis .cite journal
title = One-Pot Synthesis and Aromatization of 1,4-Dihydropyridines in Refluxing Water
author = Jing-Jing Xia, Guan-Wu Wang
journal = Synthesis
volume = 2005
issue =
pages = 2379–2383
year = 2005
url = http://www.thieme-connect.com/ejournals/abstract/synthesis/doi/10.1055/s-2005-870022
doi = 10.1055/s-2005-870022
format = abstract]The Hantzsch dihydropyridine synthesis is found to benefit from
microwave chemistry . [cite journal
title = Synthesis and Aromatization of Hantzsch 1,4-Dihydropyridines under Microwave Irradiation. An Overview
author = Jean Jacques Vanden Eynde, Annie Mayence
journal = Molecules
volume = 8
issue =
pages =
year = 2003
url = http://www.mdpi.org/molecules/papers/80400381.pdf]Knoevenagel-Fries modification
The Knoevenagel-Fries modification allows for the synthesis of unsymmetrical pyridine compounds [Synthesen in der Pyridinreihe. Ueber eine Erweiterung der Hantzsch'schen Dihydropyridinsynthese
Berichte der deutschen chemischen Gesellschaft 1898 (p 761-767) E. Knoevenagel, A. Fries DOI|10.1002/cber.189803101157] .References
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