Hantzsch pyridine synthesis
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The Hantzsch pyridine synthesis or Hantzsch dihydropyridine synthesis is a multi-component organic reaction between an aldehyde such as formaldehyde, 2 equivalents of a β-keto ester such as ethyl acetoacetate and a nitrogen donor such as ammonium acetate or ammonia . The initial reaction product is a dihydropyridine which can be oxidized in a subsequent step to a pyridine. The driving force for this second reaction step is aromatization.
A 1,4-dihydropyridine dicarboxylate is also called a 1,4-DHP compound or a Hantzsch compound. These compounds are an important class of calcium channel blockers and as such commercialized in for instance nifedipine, amlodipine or nimodipine.
The reaction has been demonstrated to proceed in water as reaction solvent and with direct aromatization by ferric chloride or potassium permanganate in a one-pot synthesis .
The Hantzsch dihydropyridine synthesis is found to benefit from microwave chemistry .
[edit] References
- ^ Condensationprodukte aus Aldehydammoniak und Ketoniartigen Verbindungen Hantzsch, A. . Ber. 1881, 14, 1637-1638.
- ^ One-Pot Synthesis and Aromatization of 1,4-Dihydropyridines in Refluxing Water Jing-Jing Xia, Guan-Wu Wang Synthesis 2005: 2379-2383 Abstract
- ^ Synthesis and Aromatization of Hantzsch 1,4-Dihydropyridines under Microwave Irradiation. An Overview Jean Jacques Vanden Eynde, Annie Mayence Molecules 2003, 8 Online article
