Tetrahydropyridine

Tetrahydropyridine
	; Three isomers of tetrahydropyridine
Identifiers
CAS Number	2,3,4,5: 505-18-0; 1,2,3,4: 37497-65-7; 2,3,4,6: 694-05-3;
3D model (JSmol)	2,3,4,5: Interactive image; 1,2,3,4: Interactive image; 2,3,4,6: Interactive image;
ChEBI	CHEBI:26145; 2,3,4,5: CHEBI:47858; 1,2,3,4: CHEBI:47859; 2,3,4,6: CHEBI:47860;
ChemSpider	2,3,4,5: 61469; 1,2,3,4: 8351589; 2,3,4,6: 12226;
EC Number	2,3,4,6: 211-766-2;
KEGG	2,3,4,5: C06181;
PubChem CID	2,3,4,5: 68161; 1,2,3,4: 10176084; 2,3,4,6: 12750;
UNII	2,3,4,6: 26RLS9D255;
UN number	2410
CompTox Dashboard (EPA)	2,3,4,5: DTXSID20198514; 1,2,3,4: DTXSID40436364; 2,3,4,6: DTXSID0075289;
	InChI 2,3,4,5: InChI=1S/C5H9N/c1-2-4-6-5-3-1/h4H,1-3,5H2 Key: DWKUKQRKVCMOLP-UHFFFAOYSA-N; 1,2,3,4: InChI=1S/C5H9N/c1-2-4-6-5-3-1/h2,4,6H,1,3,5H2 Key: VSWICNJIUPRZIK-UHFFFAOYSA-N; 2,3,4,6: InChI=1S/C5H9N/c1-2-4-6-5-3-1/h1-2,6H,3-5H2 Key: FTAHXMZRJCZXDL-UHFFFAOYSA-N;
	SMILES 2,3,4,5: C1CCN=CC1; 1,2,3,4: C1CC=CNC1; 2,3,4,6: C1CNCC=C1;
Properties
Chemical formula	C5H9N
Molar mass	83.134 g·mol−1
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

Tetrahydropyridines (or piperideines) are heterocycles with the formula C₅H₉N. Three isomers exist, which differ by the location of the double bond. None of the parent species occur widely, so they are mainly of theoretical interest. Although the parent tetrahydropyridines are rare, many substituted tetrahydropyridines are known.

Preparation and occurrence

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine causes permanent symptoms of Parkinson's disease.

2,3,4,5-Tetrahydropyridine, a colorless liquid, is commercially available. It is an imine.

Illustrating another isomer of tetrahydropyridine, 6-acetyl-2,3,4,5-tetrahydropyridine occurs naturally.

Partial reduction of pyridinium salts gives N-alkyltetrahydropyridines. Treatment of N-methylpyridinium with borohydride reagents gives 1-methyl-1,2,3,6-tetrahydropyridine.^[1]^[2]

A modified Ireland-Claisen rearrangement leads to tetrahydropyridines via a silyl ketene acetal intermediate.^[3]

Ring-closing olefin metathesis has also been used to establish the tetrahydropyridine ring system.^[4]

References

^ Balasubramanian, Marudai (2013). "Formation of Completely or Partially Reduced Pyridines and Quinolines". Pyridines: From lab to production. pp. 413–458. doi:10.1016/B978-0-12-385235-9.00005-9. ISBN 9780123852359.
^ Thyagarajan, G.; May, E. L. (1971). "Improved synthesis of 2-benzyl-1,2,5,6-tetrahydropyridines, precursors of analgetic 6,7-benzomorphans". J. Heterocycl. Chem. 8 (3): 465. doi:10.1002/jhet.5570080317.
^ Angle, S. R.; Henry, R. M. (1998). "Studies toward the Synthesis of (+)-Palustrine: The First Asymmetric Synthesis of (−)-Methyl Palustramate". J. Org. Chem. 63 (21): 7490–7497. doi:10.1021/jo980749g. PMID 11672402.
^ Deiters, A.; Martin, S. F. (2004). "Synthesis of oxygen- and nitrogen-containing heterocycles by ring-closing metathesis". Chem. Rev. 104 (5): 2199–238. doi:10.1021/cr0200872. PMID 15137789.

[1] Balasubramanian, Marudai (2013). "Formation of Completely or Partially Reduced Pyridines and Quinolines". Pyridines: From lab to production. pp. 413–458. doi:10.1016/B978-0-12-385235-9.00005-9. ISBN 9780123852359.

[2] Thyagarajan, G.; May, E. L. (1971). "Improved synthesis of 2-benzyl-1,2,5,6-tetrahydropyridines, precursors of analgetic 6,7-benzomorphans". J. Heterocycl. Chem. 8 (3): 465. doi:10.1002/jhet.5570080317.

[3] Angle, S. R.; Henry, R. M. (1998). "Studies toward the Synthesis of (+)-Palustrine: The First Asymmetric Synthesis of (−)-Methyl Palustramate". J. Org. Chem. 63 (21): 7490–7497. doi:10.1021/jo980749g. PMID 11672402.

[4] Deiters, A.; Martin, S. F. (2004). "Synthesis of oxygen- and nitrogen-containing heterocycles by ring-closing metathesis". Chem. Rev. 104 (5): 2199–238. doi:10.1021/cr0200872. PMID 15137789.

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